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Calculator Index
Every calculator on the site, in one place. Search by name or filter by category.
Tip: search matches the calculator name, description, category, and related keywords (e.g. "loan", "BMR", "tip"). Use ↑ ↓ to navigate results and Enter to open.
Or narrow results by category — pick All to see everything, or tap one or more categories to combine them. Numbers show how many calculators are in each.
Showing 128 of 128 calculators
Money(25)
Mortgage Refinance
Monthly savings, break-even point, and lifetime savings from refinancing.
Sales Tax Calculator
Add sales tax, GST, HST, or VAT to any price and see the final total.
Inflation Calculator
What a dollar from any year is worth today — adjust for the inflation rate.
Credit Card Payoff
How long it takes — and how much interest you'll pay — at your current monthly payment.
Hourly to Salary
Convert hourly wage to annual salary (and back) with custom hours per week.
Self-Employment Tax
Estimate 1099 SE tax, federal and state income tax, and quarterly payments.
HELOC Calculator
Home equity line of credit: max borrow, interest-only payment, and full repayment cost.
Currency Converter
Live exchange rates between major world currencies — updated daily (ECB).
Cost of Living Comparison
Salary you need in another city to maintain the same standard of living.
Wedding Budget Calculator
Standard wedding budget breakdown across venue, catering, photo, attire, flowers, music, and more.
Time(14)
Moon Phase Calculator
Today's moon phase, illumination percent, and the next full moon, new moon, and quarter moons.
Lunar Age Calculator
How many lunar months, full moons, and new moons between any two dates.
Date Difference
Days, weeks, months, and years between any two dates — with optional business-days-only count.
Add or Subtract Days
Add or subtract days, weeks, months, years, or business days from any date.
Days From Today
What date is 30, 60, or 90 days from today? Calendar days or business days, with day of the week.
Stopwatch & Countdown Timer
Drift-free stopwatch with laps and a countdown timer with audible alert — millisecond accuracy.
Business Days Calculator
Count business days between two dates or add/subtract working days from any date, with custom holidays excluded.
Time Since Calculator
How long it's been since any date — years, months, days, hours, minutes, and live-ticking seconds. Birthdays, quit dates, milestones.
Health(18)
Waist-to-Height Ratio
Keep your waist under half your height — the simple cardiometabolic risk screen.
Body Roundness Index (BRI)
Models the body as an ellipse from waist and height — predicts mortality risk better than BMI.
Calorie Calculator (TDEE)
Daily calories to lose, maintain, or gain weight using Mifflin-St Jeor.
Steps to Miles & Kilometers
Convert your daily step count to miles and kilometers — see both at once.
Macro Calculator
Daily protein, carbs, and fat targets for cutting, maintenance, or bulking based on your TDEE.
BMR Calculator
Basal metabolic rate using Mifflin-St Jeor and Harris-Benedict, with activity-multiplier TDEE.
Body Fat Calculator
Estimate body fat percent with the US Navy circumference method, plus a BMI-based check.
One-Rep Max (1RM)
Estimate your 1RM from a working set using Epley, Brzycki, Lombardi, O'Conner, and Lander formulas.
Ideal Weight Calculator
Estimate ideal body weight from height, sex, and frame using Hamwi, Devine, Robinson, and Miller formulas, plus the healthy-BMI range.
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.
Ovulation Calculator
Estimated ovulation date, six-day fertile window, and next expected period from your last menstrual period and cycle length.
Education(30)
Grade Needed Calculator
Find the GPA you need on remaining coursework to hit a target cumulative GPA.
Fraction Calculator
Add, subtract, multiply, and divide fractions and mixed numbers — results returned simplified, as a mixed number, and as a decimal.
Standard Deviation Calculator
Mean, median, mode, range, sample/population standard deviation, variance, quartiles, IQR, and SEM for any list of numbers.
Course Grade Calculator
Weighted course grade from assignments, quizzes, and exams. Shows current grade plus the score needed on remaining work.
Scientific Calculator
Free online scientific calculator with trig, logs, exponents, square roots, parentheses, and constants pi and e.
Area of a Circle Calculator
Find the area of a circle from its radius, diameter, or circumference with the exact formula A = π × r².
Circumference Calculator
Find the circumference of a circle from its radius, diameter, or area using C = 2 × π × r.
Cylinder Volume Calculator
Volume and surface area of any cylinder from its radius and height using V = π × r² × h.
Sphere Volume Calculator
Volume and surface area of a sphere from its radius or diameter — uses V = (4/3) × π × r³.
Cone Volume Calculator
Volume, slant height, and surface area of a cone from base radius and height using V = (1/3) × π × r² × h.
Rectangular Prism Volume Calculator
Volume, surface area, and diagonal of a rectangular box from length, width, and height (V = L × W × H).
Average Calculator
Mean, median, mode, sum, count, min, max, and range for any list of numbers.
Random Number Generator
Generate random integers between any minimum and maximum, with or without duplicates — for raffles, drawings, dice rolls, and sampling.
Proportion Calculator
Solve any proportion a/b = c/d for the missing value using cross-multiplication.
Percentage Increase / Decrease Calculator
Percent change between any old and new value, with the formula and direction shown.
Slope & Grade Calculator
Convert rise and run into decimal slope, percent grade, angle, and 1:N ratio — for ramps, roofs, roads, stairs.
Z-Score Calculator
Convert a value to a z-score, percentile, and tail probabilities using the standard normal distribution.
Normal Distribution Calculator
Find P(X<x), P(X>x), and between-range probabilities for any normal distribution with mean μ and SD σ.
Binomial Distribution Calculator
Compute P(X=k), cumulative probabilities, mean, and variance for n trials with success probability p.
Poisson Distribution Calculator
Model rare events with rate λ — get P(X=k), cumulative probability, mean, and variance.
Permutations & Combinations Calculator
Compute nPr (order matters) and nCr (order doesn't) with full counting-principle explanation.
Bayes' Theorem Calculator
Update prior beliefs with new evidence using Bayes' rule — posterior probability with tree diagram.
Confidence Interval Calculator
Compute z or t confidence intervals for a mean, with margin of error breakdown.
T-Test Calculator
One-sample and two-sample t-tests with t-statistic, p-value, and rejection regions.
Chi-Square Calculator
Goodness-of-fit and independence tests with expected counts, chi-square statistic, and p-value.
Correlation Calculator
Pearson correlation coefficient r with scatter plot, regression line, and interpretation guide.
Conversions(10)
Temperature Converter
Convert between Fahrenheit, Celsius, and Kelvin instantly in either direction.
Square Meters to Square Feet
Convert between m² and ft² — plus square yards, acres, and hectares.
Cooking Conversions
Cups, tablespoons, grams, ounces, and milliliters — plus oven temperature conversions.
Gas Mileage Calculator
MPG from miles and gallons, plus total trip fuel cost at any price per gallon.
Roman Numeral Converter
Convert between Arabic numbers and Roman numerals — both directions, 1 to 3999, with validation.
Shoe Size Converter
Convert shoe sizes between US (men's & women's), UK, European, Japanese (cm), and foot length in centimetres.
ml to oz Converter
Convert milliliters to fluid ounces — covers both US (29.57 ml) and UK Imperial (28.41 ml) fluid ounces.
Home(11)
Party Drink Calculator
How much beer, wine, liquor, ice, and cups you need based on guests, hours, and drink mix.
Party Food Calculator
How many appetizers, ounces of main, sides, and desserts you need per person.
Catering Calculator
Food quantities, staff count, and total bill (with service charge, tax, gratuity) for any event style.
Concrete Calculator
Cubic yards needed for slabs, driveways, and patios — plus bags and cost.
Paint Calculator
Gallons of paint needed for a room or surface — adjusts for doors, windows, coats, and ceiling.
Solar Panel Savings Calculator
Annual kWh production, first-year electric-bill savings, simple payback in years, and 25-year savings from rooftop solar.