Calculators that show their work

CD Calculator

Work out what a certificate of deposit will be worth at maturity: final balance, total interest, and the effective AP…

Mortgage Calculator

Estimate your monthly mortgage payment (principal, interest, taxes, insurance, PMI, HOA) and total interest, for any …

Tip Calculator

Work out the tip and per-person total on a restaurant bill, with a toggle for tipping on the pre-tax subtotal vs. the…

Markup Calculator

Solve for selling price, cost, or markup percentage from the other two, and see the corresponding margin percentage e…

WACC Calculator

Calculate a company's weighted average cost of capital from its equity and debt weights, cost of equity (CAPM or a di…

Square Footage Calculator

Calculate the square footage of a room or area from its measurements, with conversions to square meters, square yards…

Pool Calculator

Find your pool's volume in gallons from its shape and dimensions, or work out how much salt to add to reach a saltwat…

Stair Calculator

Calculate stair layout from total rise: riser count, riser height in carpenter fractions, tread run, stringer length,…

Concrete Calculator

Calculate how much concrete a slab, footing, wall, column, or post hole needs in cubic feet and cubic yards, plus how…

Board Foot Calculator

Work out board feet for lumber from actual thickness, width, and length, with a rough-sawn quarter-thickness shortcut…

Asphalt Calculator

Estimate tons of hot mix or recycled asphalt for a driveway, lot, or base repair from paved area and compacted depth,…

Topsoil Calculator

Work out cubic yards, weight, and bag count for a lawn, garden bed, or raised bed from its shape, area, and fill dept…

Conduit Fill Calculator

Check whether a set of THHN/THWN-2 conductors fits inside an EMT, IMC, RMC, or PVC conduit under the NEC Chapter 9 fi…

SAT Score Calculator

Convert raw scores on a paper SAT practice test into scaled section scores and a 400–1600 total, using College Board’…

GPA Calculator

Calculate your unweighted or weighted GPA from letter grades and credit hours, using the standard 4.0-scale grade-poi…

Words to Pages Calculator

Convert a word count into an estimated page count (or the reverse), based on font, size, and line spacing. Uses the s…

Molarity Calculator

Convert between mass, molar mass, and volume to solve for molarity, grams of solute, solution volume, or molar mass, …

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin instantly, with reference tables for oven temperatures, fever/body-te…

BMI Calculator

Calculate BMI from weight and height in US or metric units, see your CDC/WHO category and healthy-weight range, plus …

Calorie Calculator

Find your BMR, maintenance calories (TDEE), and a daily calorie target to lose, maintain, or gain weight, using the M…

Steps to Miles Calculator

Convert steps to miles or kilometers using a stride length estimated from your height and gender, not a flat 2,000-st…

Body Surface Area (BSA) Calculator

Calculate body surface area from height and weight using the Mosteller or Du Bois formula, in US or metric units, wit…

FFMI Calculator

Calculate your Fat-Free Mass Index and height-normalized FFMI from weight, height, and body fat percentage, and see h…

Coin Flip Simulator & Probability Calculator

Flip 1-500 virtual coins (fair or weighted) and see the heads/tails split and longest streak, or use the probability …

Reaction Time Test

Test your simple reaction time over several trials, then compare your average, best, median, and consistency against …

Click Speed Test

Measure your clicks per second (CPS) and clicks per minute over a timer you choose, then compare your result against …

Length Converter

Convert millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles, with reference tables for heigh…

Weight Converter

Convert between micrograms, milligrams, grams, kilograms, ounces, pounds, stone, and US tons instantly, with referenc…

Time Converter

Convert between seconds, minutes, hours, days, weeks, months, and years instantly, with reference tables and worked e…

Volume Converter

Convert between teaspoons, tablespoons, fluid ounces, cups, pints, quarts, gallons, milliliters, and liters, plus kit…

Number Base Converter

Convert between binary, octal, decimal, and hexadecimal instantly, with a byte-value reference table and worked examp…

Electrical Converter (Watts, Amps, Volts)

Convert between watts, amps, and volts for DC, AC single-phase, and AC three-phase circuits, with power factor suppor…

Percentage Calculator

Find a percentage of a number, calculate percentage increase or decrease, apply a discount, or compare two values wit…

Fraction Calculator

Add, subtract, multiply, or divide two fractions (including mixed numbers), simplify a fraction to lowest terms, or c…

Shape Volume & Surface Area Calculator

Find the volume and surface area of a rectangular prism, cylinder, sphere, or cone. Enter the dimensions in ft, in, y…

Rounding Calculator

Round any number to a chosen number of decimal places or significant figures, with a choice of seven rounding methods…

System of Equations Solver

Solve a system of 2 or 3 linear equations by Gaussian elimination, entered as ax + by = c (or ax + by + cz = d). Repo…

Date Calculator

Find the number of days between two dates, add or subtract days from a date, or count down to New Year's Day, Hallowe…

World Clock & Time Zone Converter

See the current time in dozens of cities worldwide, or convert a specific date and time from one time zone to another…

Time Duration Calculator

Find the elapsed time between two clock times, add or subtract hours and minutes from a time, or calculate the durati…

Age Difference Calculator

Find the exact age gap between two people from their birth dates, in years/months/days and as a percentage of the old…

Keg Calculator

Work out how many 12 oz beers, US pints, or custom pours a keg holds for any standard US or metric keg size, plus how…

Pizza Calculator

Work out how many pizzas to order for a group of adults and kids, by appetite and pizza size, plus a slices-per-size …

Rice to Water Ratio Calculator

Find how much water a given amount of dry rice needs, by type (white, brown, jasmine, basmati, arborio, wild rice, an…

Sentence Counter

Count sentences, words, and characters in text, plus reading time and Flesch readability scores, using Flesch's 1948 …

Wingdings Translator

Convert text to Wingdings two different ways: a Unicode symbol preview that renders on any device, and the real Windo…

Words Per Minute (WPM) Average Calculator

Turn a word or character count, time taken, and error count into gross WPM, net WPM, and accuracy, then see it placed…

Prorated Rent Calculator

Work out the partial-month rent for a mid-month move-in or move-out, and compare what the three common day-count meth…

Dead Pixel Test

Check a monitor, laptop, or phone screen for dead, hot, and stuck pixels with a full-screen color test, plus a pixel-…

Keyboard Test

Test every key on your keyboard with a live virtual layout, check how many keys register at once (rollover), and see …

Golf Club Distance Chart

See typical yardage for every club in the bag by skill level, or enter your own driver distance to scale the whole ch…