All calculators
170 calculators, each with its formula and a worked example.
Finance (26)
Mortgage Calculator
Monthly payment, total interest and full cost of a home loan.
Loan Calculator
Monthly payment and total interest for any fixed-rate loan.
Auto Loan Calculator
Car loan payments including sales tax, down payment and trade-in.
Compound Interest Calculator
How money grows when interest earns interest, with optional regular contributions.
Simple Interest Calculator
Interest on the original principal only: I = P × r × t.
Savings Calculator
Grow a savings balance with monthly deposits and interest.
Retirement Calculator
Project your retirement savings from now to your retirement age.
ROI Calculator
Return on investment, net gain and annualized return.
CAGR Calculator
Compound annual growth rate between two values.
Present Value Calculator
What a future sum is worth in today's money.
Future Value Calculator
What a sum invested today will grow to.
Annuity Calculator
Future and present value of a series of equal payments.
APR Calculator
The true annual percentage rate of a loan, fees included.
Credit Card Payoff Calculator
Months to clear a card balance and the interest it will cost.
Debt-to-Income Ratio Calculator
Front-end and back-end DTI ratios lenders use to judge applications.
Income Tax Calculator (US Federal)
Estimate 2024 US federal income tax, effective and marginal rates.
Salary to Hourly Wage Calculator
Convert an annual salary to hourly, weekly and monthly pay.
Tip Calculator
Tip amount, total bill and the split per person.
Discount Calculator
Sale price and savings from a percentage discount.
Sales Tax Calculator
Add sales tax to a price, or extract it from a total.
Profit Margin Calculator
Gross profit, margin percentage and markup from revenue and cost.
Markup Calculator
Selling price from cost and markup percentage.
Break-Even Calculator
Units and revenue needed to cover all costs.
Inflation Calculator
Future prices and the shrinking purchasing power of money.
Savings Goal Calculator
The monthly deposit needed to hit a target by a deadline.
Exchange Rate Calculator
Convert an amount at an exchange rate you supply.
Math (24)
Percentage Calculator
Find X% of a number, or work out what percent one number is of another.
Percentage Change Calculator
Percentage increase or decrease between an old value and a new value.
Fraction Calculator
Simplify a fraction and see it as a mixed number, decimal and percentage.
Average Calculator
Mean of a list of numbers, with the sum and count shown.
Mean, Median & Mode Calculator
Mean, median, mode and range of a list of numbers in one go.
Standard Deviation Calculator
Population and sample standard deviation, variance and mean of a data set.
Ratio Calculator
Simplify a ratio to lowest terms and scale it up or down.
Proportion Calculator
Solve a/b = c/x for whichever value is missing.
Exponent Calculator
Calculate base raised to any power, plus its square and cube.
Logarithm Calculator
Logarithm of a number in base 10, e, 2 or any custom base.
Square Root Calculator
Square root, cube root and any nth root of a number.
Factorial Calculator
n! — the product of all whole numbers from 1 to n, exactly.
GCD & LCM Calculator
Greatest common divisor and least common multiple of two integers.
Pythagorean Theorem Calculator
Find the hypotenuse or a missing leg of a right triangle.
Quadratic Equation Calculator
Roots and discriminant of ax² + bx + c = 0, including complex roots.
Slope Calculator
Slope, distance, midpoint and angle between two points.
Area Calculator
Area of a square, rectangle, circle, triangle, trapezoid, parallelogram or ellipse.
Perimeter Calculator
Perimeter of squares, rectangles, triangles and regular polygons, plus circumference.
Volume Calculator
Volume of a cube, cuboid, sphere, cylinder, cone or pyramid.
Circle Calculator
Diameter, circumference and area from a circle's radius.
Triangle Calculator
Triangle area from base and height, or area and perimeter from three sides (Heron).
Random Number Range Analyzer
Honest range analysis: how many integers a range holds and the chance of any one of them.
Scientific Notation Calculator
Convert a decimal number into scientific notation: coefficient × 10^exponent.
Rounding Calculator
Round a number to decimal places or to significant figures.
Health & Fitness (22)
BMI Calculator
Body mass index from your weight and height, with the standard weight category.
BMR Calculator
Basal metabolic rate — the calories your body burns at complete rest.
TDEE Calculator
Total daily energy expenditure — your true maintenance calories.
Calorie Calculator
Daily calorie target for losing, maintaining or gaining weight.
Body Fat Calculator
Estimate body fat percentage from tape measurements — the US Navy method.
Ideal Weight Calculator
Devine ideal body weight for your height, plus the healthy BMI weight range.
Macro Calculator
Split daily calories into grams of carbohydrate, protein and fat.
Protein Calculator
Daily protein target in grams, scaled to your body weight and goal.
Water Intake Calculator
Suggested daily water intake from body weight and exercise.
Ovulation Calculator
Ovulation day, fertile window and next period from your last period.
Pregnancy Due Date Calculator
Due date by Naegele's rule, plus gestational age and trimester for any date.
Conception Calculator
Work backwards from a due date to the estimated conception date.
Period Calculator
Predict your next three period start dates from your cycle length.
Pace Calculator
Running pace per kilometre and per mile, plus speed, from distance and time.
Heart Rate Zones Calculator
Five training zones from your age-predicted maximum heart rate.
VO2 Max Calculator
Estimate aerobic fitness with the Rockport one-mile walk test.
One Rep Max Calculator
Estimate your 1RM from a submaximal set — Epley and Brzycki formulas.
Sleep Calculator
Bedtimes and wake times that line up with complete 90-minute sleep cycles.
Blood Alcohol Calculator (BAC)
Estimate blood alcohol concentration with the Widmark formula.
Lean Body Mass Calculator
Lean body mass from the Boer formula, with implied fat mass.
Calories Burned Calculator
Energy cost of common activities from MET values, weight and duration.
Pregnancy Weight Gain Calculator
IOM 2009 recommended weight-gain ranges by pre-pregnancy BMI.
Date & Time (18)
Age Calculator
Exact age in years, months and days from a birth date.
Date Duration Calculator
The length of a period as years, months and days, plus total days.
Days Between Dates Calculator
Total days, weeks and business days between two dates.
Add Days to Date Calculator
The date a number of calendar or business days from a start date.
Business Days Calculator
Working days and weekend days between two dates.
Work Hours Calculator
Daily and weekly hours worked and pay, breaks included.
Time Duration Calculator
Elapsed time between two date-times in hours, minutes and days.
Time Zone Converter
Convert a date and time between world time zones, DST aware.
Week Number Calculator
ISO 8601 week number, week year and day of year for any date.
Day of Week Calculator
Which weekday any date falls on — past or future.
Leap Year Calculator
Is a year a leap year? Days in the year, February length and the next leap year.
Unix Timestamp Converter
Convert Unix timestamps (seconds) to dates and back, in UTC.
Time Add / Subtract Calculator
Add or subtract hours, minutes and seconds from a time of day.
Days Until Calculator
Countdown in days and weeks from one date to another.
Zodiac Sign Calculator
Your Western zodiac sign from your birth month and day.
Chinese Zodiac Calculator
Chinese zodiac animal, element and yin/yang for a birth year.
Retirement Date Calculator
The calendar date you reach retirement age, and the time left until then.
Quarter Calculator
Calendar and fiscal quarter of a date, plus its day within the quarter.
Unit Conversions (26)
Length Converter
Convert mm, cm, metres, kilometres, inches, feet, yards, miles and nautical miles.
Weight Converter
Convert mg, grams, kilograms, tonnes, ounces, pounds, stone and US tons.
Temperature Converter
Convert Celsius, Fahrenheit and Kelvin with absolute-zero validation.
Volume Converter
Convert litres, ml, cubic metres, US and imperial gallons, cups, tablespoons and teaspoons.
Area Converter
Convert square metres, hectares, acres, square feet, yards, miles and inches.
Speed Converter
Convert m/s, km/h, mph, knots, ft/s and Mach number.
Time Converter
Convert seconds, minutes, hours, days, weeks and Julian years.
Data Storage Converter
Convert bits, bytes, KB, MB, GB, TB and the IEC KiB, MiB, GiB, TiB.
Pressure Converter
Convert pascal, kPa, MPa, bar, atm, psi, Torr and inHg.
Energy Converter
Convert joules, kJ, calories, kcal, kWh, BTU and foot-pounds.
Power Converter
Convert watts, kilowatts, megawatts, horsepower (mechanical and metric) and BTU/hr.
Force Converter
Convert newtons, kilonewtons, dynes, kilogram-force and pound-force.
Torque Converter
Convert N·m, kN·m, lbf·ft, lbf·in and kgf·m.
Angle Converter
Convert degrees, radians, gradians, turns, arcminutes and arcseconds.
Fuel Consumption Converter
Convert mpg (US), mpg (imperial), L/100km and km/L.
Cooking Converter
Convert cups, tablespoons, teaspoons, ml, litres and fluid ounces — plus grams for common ingredients.
Shoe Size Converter
Convert foot length in cm to US men's, US women's, UK and EU shoe sizes.
Density Converter
Convert kg/m³, g/cm³, g/mL, lb/ft³ and lb per US gallon.
Frequency Converter
Convert Hz, kHz, MHz, GHz and RPM, with the period in milliseconds.
Height Converter
Convert centimetres to feet and inches, or feet and inches back to centimetres.
Flow Rate Converter
Convert L/min, L/s, m³/h, US gallons per minute and cubic feet per minute.
Number to Words Converter
Spell out any whole number from 0 to 999,999,999 in English words.
Roman Numeral Converter
Convert numbers 1–3999 to Roman numerals, and valid Roman numerals back to numbers.
Beaufort Scale Converter
Turn wind speed in km/h, mph, m/s or knots into a Beaufort number and description.
Screen Size Calculator
From diagonal and aspect ratio to screen width, height and area.
Decibel Converter
Convert power and amplitude ratios to decibels, and decibels back to ratios.
Construction & Home (18)
Concrete Calculator
Cubic yards, cubic feet and bags of concrete for a slab, footing or post hole pad.
Tile Calculator
Tiles and boxes needed for a floor or wall, including cutting waste.
Paint Calculator
Gallons and liters of paint for a room, minus doors and windows, per coat.
Flooring Calculator
Boxes of laminate, vinyl or engineered flooring for a room, waste included.
Drywall Calculator
Sheetrock sheets needed for walls and ceiling in 4×8 or 4×12 sheets.
Brick Calculator
Bricks needed for a wall, from the brick face size and a 3/8-inch mortar joint.
Gravel Calculator
Cubic yards and tons of gravel for a driveway, path or drainage bed.
Mulch Calculator
Bags, cubic feet and cubic yards of mulch for garden beds.
Deck Calculator
Deck boards, linear feet and screw count for a rectangular deck.
Fence Calculator
Panels, posts, rails and concrete bags for a panel fence run.
Roof Pitch Calculator
Pitch (x/12), roof angle, slope percent and rafter length from rise and run.
Roofing Material Calculator
Roof area, squares, shingle bundles and underlayment rolls for a roof.
Stairs Calculator
Risers, treads, total run and stringer length for a straight staircase.
Square Footage Calculator
Area in square feet and square meters for rectangles, triangles, circles and trapezoids.
Cubic Yard Calculator
Convert length × width × depth into cubic yards, cubic feet and cubic meters.
Board Feet Calculator
Board feet and cubic volume of lumber from nominal dimensions and quantity.
Insulation Calculator
Batts and packages of insulation for a stud wall, by stud spacing.
Wallpaper Calculator
Rolls of wallpaper for a room, including pattern-repeat waste.
Science (18)
Ohm's Law Calculator
Solve for voltage, current, resistance or power from any two known values.
Parallel Resistor Calculator
Equivalent resistance for resistors in parallel (and in series, for comparison).
Velocity Calculator
Find velocity, distance or time from the other two quantities.
Acceleration Calculator
Acceleration from a change in velocity, plus the distance covered.
Kinetic Energy Calculator
Energy of a moving object: KE = ½mv².
Potential Energy Calculator
Gravitational potential energy near Earth's surface: PE = mgh.
Force Calculator
Newton's second law: F = m × a, with weight on Earth as a bonus.
Momentum Calculator
Linear momentum p = mv, with kinetic energy shown alongside.
Friction Calculator
Friction force from the coefficient of friction and the object's weight.
Projectile Range Calculator
Range, maximum height and flight time for a projectile on flat ground.
Pendulum Calculator
Period and frequency of a simple pendulum — or the length for a target period.
Wavelength Calculator
Wavelength from frequency (or the reverse) for sound, light or any wave speed.
pH Calculator
pH and pOH from hydrogen ion concentration — or concentration from pH.
Molarity Calculator
Concentration in mol/L from moles and volume — or solve for either one.
Dilution Calculator
M₁V₁ = M₂V₂: solve any one dilution value from the other three.
Ideal Gas Calculator
PV = nRT: solve for pressure, volume, moles or temperature.
Boyle's Law Calculator
P₁V₁ = P₂V₂ for a gas at constant temperature.
Half-Life Calculator
Amount remaining after radioactive decay — or the time a decay took.
Everyday Life (18)
GPA Calculator
Grade point average from letter grades and credit hours.
Grade Calculator
The exam score you need to reach your target final grade.
Final Grade Calculator
Your final course grade from a hypothetical exam score.
Weighted Grade Calculator
Weighted average grade from assignments and their weights.
Dog Age Calculator
Your dog's age in human years, adjusted for size.
Cat Age Calculator
Your cat's age in human years.
Electricity Cost Calculator
What an appliance costs to run, per day, month and year.
Fuel Cost Calculator
Fuel needed and trip cost for a drive, US or metric.
Split Bill Calculator
Split a bill with tip and tax evenly between people.
Unit Price Calculator
Compare two products by price per unit and see the saving.
Reading Time Calculator
How long a text takes to read — and to read aloud.
Subnet Calculator
Network, broadcast, usable hosts and masks for an IPv4 CIDR block.
Download Time Calculator
How long a download takes at a given connection speed.
Probability Calculator
Probability as a percentage, decimal and '1 in X' odds.
Rent Affordability Calculator
How much rent you can afford — and the income a rent requires.
Solar Payback Calculator
Solar payback period and 25-year savings with price inflation.
Household Budget Calculator
Split monthly take-home pay with the 50/30/20 rule — or your own.
Emergency Fund Calculator
Your target emergency fund and how long it will take to build.