The Handy Calculators logoTheHandyCalculators.com
    128 calculators · 100% free · no signup

    Every everyday calculator, in one place.

    Find free online calculators for personal finance, dates and time, health estimates, school math, unit conversions, and home improvement projects.

    About this site

    Free calculators built by a working appraiser and broker — not a content farm

    The Handy Calculators is a small, independent site with one job: give you the exact number you came for, then explain how it was calculated so you can trust it.

    Every tool on this site is hand-built around a real decision — a mortgage you're weighing, a paycheck you're negotiating, a training plan you're starting, a deadline you're counting down to. The formulas come from primary sources: IRS publications for take-home pay, the Mifflin-St Jeor equation for calories, Fannie Mae and Freddie Mac amortization conventions for mortgages, ASHRAE and building-code references for home projects, and peer-reviewed research for the health estimators. When a calculator uses an assumption you can override — a tax bracket, a discount rate, a maintenance reserve — you'll see the assumption spelled out, not buried.

    Nothing here is auto-generated fluff. Each page is written and reviewed by a human, tested against worked examples, and updated when the underlying rates, brackets, or standards change. There are no popups, no email walls, no dark-pattern upsells, and the site runs entirely in your browser — none of your inputs leave your device.

    Sourced, not scraped

    Formulas cite IRS, Fannie Mae, ASHRAE, ACSM, and peer-reviewed research — not other calculator sites.

    Worked-example tested

    Every tool is checked against at least one manually-worked example before it ships, and re-tested when rates change.

    Private by default

    Calculations run entirely in your browser. No accounts, no data collection on inputs, no results sent anywhere.

    Real-life scenarios

    Built for the decisions you actually make

    TheHandyCalculators.com isn't a math reference — it's a decision toolkit. Every calculator is designed around a real situation people face at home, at work, at school, or on the move. Here are a few of the moments our tools were built for.

    Buying or refinancing a home

    Compare a 30-year vs 15-year mortgage, see exactly how much a 1% rate cut saves over the life of the loan, find your break-even on a refinance, and budget for closing costs before you sign anything.

    Negotiating a job offer

    Translate a salary offer into real take-home pay by state, compare an hourly contract to a salaried role, and stress-test whether a relocation makes sense after taxes, cost of living, and benefits.

    Getting healthier this year

    Find your daily calorie target with Mifflin-St Jeor TDEE, dial in a sustainable deficit, track BMI and body-fat trends, and build a training plan around heart-rate zones and realistic running pace.

    Surviving finals week

    Calculate your current GPA, weight every assignment by syllabus category, and find the exact score you need on the final to lock in the grade you want — without guessing or scrolling through Reddit threads.

    Underwriting a real-estate deal

    Run cap rate, cash-on-cash, DSCR, and full multifamily, hotel, retail, office, or industrial proformas in seconds — the same math brokers and analysts use, without an Excel template or a paid platform.

    Planning a trip or a project

    Count business days until a deadline, line up meetings across time zones with full DST handling, convert recipes from cups to grams, or estimate concrete, paint, and tile before a weekend renovation.

    Why people keep coming back

    Fast answers, trustworthy math, no friction

    We obsess over two things: the accuracy of the underlying formulas and how quickly you can get a useful number out of them. Everything else — sign-ups, paywalls, dark patterns — gets cut.

    Instant results in your browser

    Every calculation runs locally the moment you type — no loading spinners, no server round-trips, no waiting. Most pages give you an answer in under a second on a phone over 4G.

    Research-backed formulas

    We use the same formulas trusted by clinicians, lenders, and analysts — Mifflin-St Jeor for TDEE, fully amortizing loan math, NOI / cap-rate for real estate, IRS-aligned tax tables, and unit conversions to international standards.

    Your inputs stay private

    Numbers you type — salary, weight, loan balance, health metrics — are processed in your browser and never sent to a server. There's no account, no tracking pixel tied to your answers, and no email gate.

    Built for the whole web

    Available in English, Spanish, Portuguese, and German, with metric and US units side by side, mobile-first layouts, and copy-friendly results that paste cleanly into email, Slack, or a spreadsheet.

    FAQ

    Questions people ask before using the site

    If you're new here, these are the answers most visitors want before they trust a calculator with a real decision.

    Yes. Every calculator on the site is 100% free, with no sign-up, no trial, no premium tier, and no usage limit. We're supported by unobtrusive ads, not subscriptions or data sales.

    All calculators (A–Z)

    Quick links to every tool on the site.

    128 total

    Calculator categories for common questions

    Use the category links to jump directly to related calculators, then open any tool for instant calculations and clear results. Each calculator is organized by topic so search engines and visitors can discover the most relevant pages faster.

    Money calculators

    Plan everyday financial decisions with mortgage, loan, paycheck, tax, tip, discount, savings, retirement, and investment calculators.

    25 calculators

    Mortgage Calculator

    Monthly payment, taxes, insurance, and required income.

    Open

    Mortgage Refinance

    Monthly savings, break-even point, and lifetime savings from refinancing.

    Open

    Rent vs Buy

    Compare the true 5-year cost of renting versus buying.

    Open

    Car Payment Calculator

    Monthly car payment including tax, trade-in, and down payment.

    Open

    Loan Calculator

    Monthly payment and total interest for any personal or auto loan.

    Open

    Savings Goal

    How much to save monthly to hit any goal by a target date.

    Open

    Compound Interest

    Project your investment growth over years or decades.

    Open

    401k & Retirement

    Project your retirement balance with employer match and growth.

    Open

    Investment ROI

    Total return, profit, and annualized CAGR for any investment.

    Open

    Paycheck Estimator

    Estimate take-home pay after federal, state, and FICA taxes.

    Open

    Sales Tax Calculator

    Add sales tax, GST, HST, or VAT to any price and see the final total.

    Open

    Tip Calculator

    Calculate tips and split the bill between any number of people.

    Open

    Discount Calculator

    Find the sale price after any percentage discount.

    Open

    Inflation Calculator

    What a dollar from any year is worth today — adjust for the inflation rate.

    Open

    Credit Card Payoff

    How long it takes — and how much interest you'll pay — at your current monthly payment.

    Open

    Net Worth Calculator

    Add up assets, subtract liabilities, see your total net worth.

    Open

    Hourly to Salary

    Convert hourly wage to annual salary (and back) with custom hours per week.

    Open

    Self-Employment Tax

    Estimate 1099 SE tax, federal and state income tax, and quarterly payments.

    Open

    HELOC Calculator

    Home equity line of credit: max borrow, interest-only payment, and full repayment cost.

    Open

    APR vs APY Converter

    Convert between APR and APY for any compounding frequency.

    Open

    Currency Converter

    Live exchange rates between major world currencies — updated daily (ECB).

    Open

    Cost of Living Comparison

    Salary you need in another city to maintain the same standard of living.

    Open

    Wedding Budget Calculator

    Standard wedding budget breakdown across venue, catering, photo, attire, flowers, music, and more.

    Open

    Take-Home Pay by State

    Annual and biweekly net pay after federal, FICA, and state income tax — all 50 states plus DC.

    Open

    Margin Calculator

    Profit margin, markup, and revenue from any combination of cost, selling price, and target margin.

    Open

    Time calculators

    Count days, calculate exact ages, add work hours, plan sleep cycles, and compare time zones for deadlines, travel, and schedules.

    14 calculators

    Days Until a Date

    Countdown to any future date — birthdays, holidays, deadlines.

    Open

    Age Calculator

    Your exact age in years, months, days, hours, and minutes.

    Open

    Work Hours Calculator

    Add up hours worked between start and end times, minus breaks.

    Open

    Time Zone Converter

    Convert any date and time between time zones — DST aware.

    Open

    Moon Phase Calculator

    Today's moon phase, illumination percent, and the next full moon, new moon, and quarter moons.

    Open

    Lunar Age Calculator

    How many lunar months, full moons, and new moons between any two dates.

    Open

    Date Difference

    Days, weeks, months, and years between any two dates — with optional business-days-only count.

    Open

    Add or Subtract Days

    Add or subtract days, weeks, months, years, or business days from any date.

    Open

    Days From Today

    What date is 30, 60, or 90 days from today? Calendar days or business days, with day of the week.

    Open

    Stopwatch & Countdown Timer

    Drift-free stopwatch with laps and a countdown timer with audible alert — millisecond accuracy.

    Open

    Business Days Calculator

    Count business days between two dates or add/subtract working days from any date, with custom holidays excluded.

    Open

    Time Since Calculator

    How long it's been since any date — years, months, days, hours, minutes, and live-ticking seconds. Birthdays, quit dates, milestones.

    Open

    How Long Have We Been Together?

    Enter the day your relationship started and see exactly how long you've been together — to the second. Perfect for anniversaries.

    Open

    How Long Have I Been Married?

    Enter your wedding date and see your exact marriage length in years, months, days, hours, and seconds — with traditional anniversary gifts.

    Open

    Health calculators

    Estimate wellness numbers including BMI, calories, hydration, sleep timing, pregnancy due dates, and running pace.

    18 calculators

    BMI Calculator

    Body mass index in metric or US units, with category.

    Open

    Waist-to-Height Ratio

    Keep your waist under half your height — the simple cardiometabolic risk screen.

    Open

    Body Roundness Index (BRI)

    Models the body as an ellipse from waist and height — predicts mortality risk better than BMI.

    Open

    Calorie Calculator (TDEE)

    Daily calories to lose, maintain, or gain weight using Mifflin-St Jeor.

    Open

    Water Intake

    How many ounces, cups, or liters you should drink each day.

    Open

    Sleep Calculator

    Best bedtime or wake time based on 90-minute sleep cycles.

    Open

    Pregnancy Due Date

    Estimate your due date and current week of pregnancy.

    Open

    Running Pace

    Pace per mile/km and average speed from time and distance.

    Open

    Steps to Miles & Kilometers

    Convert your daily step count to miles and kilometers — see both at once.

    Open

    Macro Calculator

    Daily protein, carbs, and fat targets for cutting, maintenance, or bulking based on your TDEE.

    Open

    BMR Calculator

    Basal metabolic rate using Mifflin-St Jeor and Harris-Benedict, with activity-multiplier TDEE.

    Open

    Body Fat Calculator

    Estimate body fat percent with the US Navy circumference method, plus a BMI-based check.

    Open

    One-Rep Max (1RM)

    Estimate your 1RM from a working set using Epley, Brzycki, Lombardi, O'Conner, and Lander formulas.

    Open

    Ideal Weight Calculator

    Estimate ideal body weight from height, sex, and frame using Hamwi, Devine, Robinson, and Miller formulas, plus the healthy-BMI range.

    Open

    Heart Rate Zone Calculator

    Calculate your five training heart-rate zones from age and resting HR using Tanaka, Fox, Gulati, or Karvonen heart-rate-reserve formulas.

    Open

    Ovulation Calculator

    Estimated ovulation date, six-day fertile window, and next expected period from your last menstrual period and cycle length.

    Open

    Dog Age Calculator

    Convert your dog's age to human years using the AVMA size-aware method or the 2019 epigenetic clock, with small/medium/large/giant adjustments.

    Open

    Calorie Deficit Calculator

    Daily calorie target for weight loss at your chosen pace, plus weeks to your goal — companion to the TDEE calculator.

    Open

    Home calculators

    Measure project materials and costs for home improvement, flooring, room area, concrete slabs, patios, and construction jobs.

    11 calculators

    Party Drink Calculator

    How much beer, wine, liquor, ice, and cups you need based on guests, hours, and drink mix.

    Open

    Party Food Calculator

    How many appetizers, ounces of main, sides, and desserts you need per person.

    Open

    Catering Calculator

    Food quantities, staff count, and total bill (with service charge, tax, gratuity) for any event style.

    Open

    Square Footage

    Area in sq ft, m², and sq yd with waste factor and material cost.

    Open

    Concrete Calculator

    Cubic yards needed for slabs, driveways, and patios — plus bags and cost.

    Open

    Wallpaper Calculator

    Rolls needed including pattern-repeat waste, doors, and windows.

    Open

    Tile Calculator

    Tiles and boxes needed with grout joint width and waste buffer.

    Open

    Paint Calculator

    Gallons of paint needed for a room or surface — adjusts for doors, windows, coats, and ceiling.

    Open

    Solar Panel Savings Calculator

    Annual kWh production, first-year electric-bill savings, simple payback in years, and 25-year savings from rooftop solar.

    Open

    Mulch & Gravel Calculator

    Cubic yards, cubic feet, bags, and tons of mulch, gravel, topsoil, or sand to cover a rectangular area at any depth.

    Open

    Lumber & Board Foot Calculator

    Calculate board feet for dimensional lumber. Add multiple sizes for total board feet, lineal feet, waste, and cost.

    Open

    Education calculators

    Solve common school and study calculations with quick percentage tools and GPA calculators for academic planning.

    30 calculators

    Percentage Calculator

    Three modes: X% of Y, A is what % of B, and % change.

    Open

    GPA Calculator

    Calculate your semester or cumulative GPA on a 4.0 scale.

    Open

    Grade Needed Calculator

    Find the GPA you need on remaining coursework to hit a target cumulative GPA.

    Open

    Fraction Calculator

    Add, subtract, multiply, and divide fractions and mixed numbers — results returned simplified, as a mixed number, and as a decimal.

    Open

    Standard Deviation Calculator

    Mean, median, mode, range, sample/population standard deviation, variance, quartiles, IQR, and SEM for any list of numbers.

    Open

    Course Grade Calculator

    Weighted course grade from assignments, quizzes, and exams. Shows current grade plus the score needed on remaining work.

    Open

    Scientific Calculator

    Free online scientific calculator with trig, logs, exponents, square roots, parentheses, and constants pi and e.

    Open

    Area of a Circle Calculator

    Find the area of a circle from its radius, diameter, or circumference with the exact formula A = π × r².

    Open

    Circumference Calculator

    Find the circumference of a circle from its radius, diameter, or area using C = 2 × π × r.

    Open

    Cylinder Volume Calculator

    Volume and surface area of any cylinder from its radius and height using V = π × r² × h.

    Open

    Sphere Volume Calculator

    Volume and surface area of a sphere from its radius or diameter — uses V = (4/3) × π × r³.

    Open

    Cone Volume Calculator

    Volume, slant height, and surface area of a cone from base radius and height using V = (1/3) × π × r² × h.

    Open

    Rectangular Prism Volume Calculator

    Volume, surface area, and diagonal of a rectangular box from length, width, and height (V = L × W × H).

    Open

    Average Calculator

    Mean, median, mode, sum, count, min, max, and range for any list of numbers.

    Open

    Random Number Generator

    Generate random integers between any minimum and maximum, with or without duplicates — for raffles, drawings, dice rolls, and sampling.

    Open

    Proportion Calculator

    Solve any proportion a/b = c/d for the missing value using cross-multiplication.

    Open

    Percentage Increase / Decrease Calculator

    Percent change between any old and new value, with the formula and direction shown.

    Open

    Slope & Grade Calculator

    Convert rise and run into decimal slope, percent grade, angle, and 1:N ratio — for ramps, roofs, roads, stairs.

    Open

    Z-Score Calculator

    Convert a value to a z-score, percentile, and tail probabilities using the standard normal distribution.

    Open

    Normal Distribution Calculator

    Find P(X<x), P(X>x), and between-range probabilities for any normal distribution with mean μ and SD σ.

    Open

    Binomial Distribution Calculator

    Compute P(X=k), cumulative probabilities, mean, and variance for n trials with success probability p.

    Open

    Poisson Distribution Calculator

    Model rare events with rate λ — get P(X=k), cumulative probability, mean, and variance.

    Open

    Permutations & Combinations Calculator

    Compute nPr (order matters) and nCr (order doesn't) with full counting-principle explanation.

    Open

    Bayes' Theorem Calculator

    Update prior beliefs with new evidence using Bayes' rule — posterior probability with tree diagram.

    Open

    Confidence Interval Calculator

    Compute z or t confidence intervals for a mean, with margin of error breakdown.

    Open

    T-Test Calculator

    One-sample and two-sample t-tests with t-statistic, p-value, and rejection regions.

    Open

    Chi-Square Calculator

    Goodness-of-fit and independence tests with expected counts, chi-square statistic, and p-value.

    Open

    Correlation Calculator

    Pearson correlation coefficient r with scatter plot, regression line, and interpretation guide.

    Open

    Linear Regression Calculator

    Least-squares slope, intercept, R², and predictions for any paired (x, y) data.

    Open

    Sample Size Calculator

    Required sample size to estimate a proportion or mean at a chosen confidence level and margin of error.

    Open

    Conversion calculators

    Convert everyday units quickly, including length, weight, volume, and temperature across metric and imperial systems.

    10 calculators

    Unit Converter

    Length, weight, and volume between metric and imperial.

    Open

    Temperature Converter

    Convert between Fahrenheit, Celsius, and Kelvin instantly in either direction.

    Open

    Square Meters to Square Feet

    Convert between m² and ft² — plus square yards, acres, and hectares.

    Open

    Cooking Conversions

    Cups, tablespoons, grams, ounces, and milliliters — plus oven temperature conversions.

    Open

    Gas Mileage Calculator

    MPG from miles and gallons, plus total trip fuel cost at any price per gallon.

    Open

    Roman Numeral Converter

    Convert between Arabic numbers and Roman numerals — both directions, 1 to 3999, with validation.

    Open

    Shoe Size Converter

    Convert shoe sizes between US (men's & women's), UK, European, Japanese (cm), and foot length in centimetres.

    Open

    ml to oz Converter

    Convert milliliters to fluid ounces — covers both US (29.57 ml) and UK Imperial (28.41 ml) fluid ounces.

    Open

    oz to Cups Converter

    Convert fluid ounces to cups (US and UK), with tablespoons and milliliters.

    Open

    Inches to cm Converter

    Convert inches to centimeters using the exact international factor (1 in = 2.54 cm) — plus mm, m, and feet.

    Open

    Real estate income proforma calculators

    Underwrite commercial real estate by property type — multifamily, hotel, retail, office, and industrial. NOI, cap-rate value, DSCR, and cash-on-cash for brokers, appraisers, and investors.

    20 calculators

    Income Proforma Hub

    Pick a property type — multifamily, hotel, retail, office, or industrial — and underwrite it.

    Open

    Multifamily Income Proforma

    Apartment building NOI, cap-rate value, value per door, and DSCR.

    Open

    Hotel Income Proforma

    ADR × Occupancy × Keys → RevPAR, NOI, and value per key.

    Open

    Retail Income Proforma

    Strip center / NNN proforma: rent PSF, CAM recovery, NOI, value per SF.

    Open

    Office Income Proforma

    Office building NOI, rent PSF, expense recoveries, and value per SF.

    Open

    Industrial Income Proforma

    Warehouse / distribution NOI, NNN rent PSF, and value per SF.

    Open

    Retail with Apartments Proforma

    Mixed-use retail + multifamily: per-component NOI, weighted cap rate, value, DSCR.

    Open

    Retail with Offices Proforma

    Mixed-use retail + office: rent PSF, CAM, weighted cap rate, NOI, value, DSCR.

    Open

    Hotel with Retail Proforma

    Mixed-use hotel + ground-floor retail: ADR, RevPAR, NNN rent, NOI, value, DSCR.

    Open

    Hotel + Retail + Apartments Proforma

    Three-use mixed-use: hotel, retail, and multifamily rolled into one NOI, value, DSCR.

    Open

    Cap Rate Calculator

    Capitalization rate from NOI and value, or solve for value, NOI, or required cap rate.

    Open

    Cash-on-Cash Return

    Annual cash flow divided by cash invested — the levered return on a rental property.

    Open

    Rental Yield Calculator

    Gross and net rental yield from purchase price, monthly rent, expenses, and vacancy.

    Open

    70% Rule Calculator

    Maximum offer for a flip — 70% of ARV minus repairs, with adjustable spread for any market.

    Open

    Commercial Loan Calculator

    Commercial mortgage payment with DSCR, interest-only period, balloon balance, and max loan sizing.

    Open

    Closing Costs Estimator

    Buyer closing-cost breakdown by line item — lender, title, government, prepaids — plus cash-to-close.

    Open

    1031 Exchange Calculator

    Deferred gain, recognized boot from cash and debt relief, federal tax owed, and carryover basis on a like-kind real estate exchange.

    Open

    1031 Exchange Boot Calculator

    Cash boot, mortgage boot, and the tax owed on a partial 1031 exchange when you buy down in price or debt.

    Open

    1031 Exchange Deadline Calculator

    45-day identification and 180-day completion deadlines for a 1031 like-kind exchange from any closing date.

    Open

    Self-Storage Proforma

    Underwrite a self-storage facility: NRSF, GPI, vacancy, NOI, cap-rate value, and value per square foot and per unit.

    Open
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