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

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

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

Project your retirement balance with employer match and growth.

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

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

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

Convert between APR and APY for any compounding frequency.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Project your investment growth over years or decades.

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

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

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

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

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

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

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

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

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

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

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

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

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

Find the sale price after any percentage discount.

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.

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

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

Calculate your semester or cumulative GPA on a 4.0 scale.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Monthly payment, taxes, insurance, and required income.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Estimate your due date and current week of pregnancy.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Length, weight, and volume between metric and imperial.

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

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

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

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

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

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