62 free calculators · no sign-up

Everyday numbers, answered properly.

Pick a calculator and get the answer, the formula behind it, a worked example and the assumptions that matter.

See all 62 →
Mortgage CalculatorMonthly payment, total interest and payoff for a home loan. BMI CalculatorBody Mass Index, WHO categories and CDC percentiles. Loan CalculatorPayment amount and total cost for any fixed-rate loan. Percentage CalculatorPercent of a number, percent change and more. Calorie CalculatorDaily calories to maintain, lose or gain weight. Age CalculatorExact age in years, months and days. Tip CalculatorTip amount, total bill and how to split it. Unit ConverterConvert length, weight, temperature and volume.

Browse by category

FinancialMortgages, loans, interest, tips & discounts Fitness & HealthBMI, calories, sleep, pace, healthy weight & more MathPercentages, fractions, area, averages, Roman numerals Weather & EnvironmentWind chill and dew point Chemistry & ScienceMolarity and solution concentration Construction & HomeRoofing and mulch estimates Other & ToolsAge, time, dates, units, Base64, GPA, embed

Fitness & Health Calculators

BMI CalculatorBody Mass Index, WHO categories, and CDC percentiles for children and teens. BMR CalculatorBasal Metabolic Rate — calories your body burns at rest. Calorie CalculatorDaily calories to maintain, lose, or gain weight based on activity. Ideal Weight CalculatorHealthy weight ranges using several common formulas. Healthy Weight (Goal) CalculatorHealthy BMI weight range for your height and a target goal. Body Fat CalculatorEstimate body fat percentage using a circumference method. Pace CalculatorFind pace, time, or distance for running and walking. Sleep CalculatorSuggested bedtimes or wake-up times based on 90-minute sleep cycles. Water Intake CalculatorDaily water target from weight and exercise time. Due Date CalculatorEstimate a due date and current weeks of pregnancy. Body Surface Area CalculatorEstimate body surface area with the Mosteller formula. Calorie Deficit CalculatorFind a target calorie intake for a safe deficit.

Financial Calculators

Mortgage CalculatorMonthly payment, total interest, and payoff for a home loan. Loan CalculatorPayment amount and total cost for any fixed-rate loan. Compound Interest CalculatorSee how savings or investments grow over time. Simple Interest CalculatorInterest earned or owed without compounding. Auto Loan CalculatorCar payment including price, down payment, and trade-in. Tip CalculatorTip amount, total bill, and how to split it. Discount & Sales Tax CalculatorFinal price after a discount and/or sales tax. Salary to Hourly CalculatorConvert a yearly salary into hourly, weekly and monthly pay. Savings Goal CalculatorSee how long a savings target takes with monthly deposits. Credit Card Payoff CalculatorSee the months and interest to clear a card balance. Overtime Pay CalculatorFigure out regular, overtime and double-time pay. Percentage Off CalculatorFind sale price and savings from a percent off. Sales Tax CalculatorAdd or reverse-calculate sales tax. CAGR CalculatorFind compound annual growth rate over time.

Math Calculators

Percentage CalculatorPercent of a number, percent change, and more. Fraction CalculatorAdd, subtract, multiply, divide, and simplify fractions. Area CalculatorArea of rectangles, circles, triangles, and more. Average CalculatorMean, median, range, and sum of a list of numbers. Random Number GeneratorPick random integers within any range. Roman Numeral ConverterConvert between numbers and Roman numerals (with formula and rules). Quadratic Equation CalculatorSolve ax² + bx + c = 0 with real or complex roots and discriminant.

Weather & Environment Calculators

Wind Chill Calculator"Feels like" temperature from air temperature and wind speed (NWS formula). Dew Point CalculatorDew point and humidity relationships from temperature and relative humidity. Heat Index Calculator"Feels like" heat from temperature and humidity.

Chemistry & Science Calculators

Molarity CalculatorSolution concentration, moles, mass, and volume with unit conversions. Dilution CalculatorSolve stock and final solution problems using M₁V₁ = M₂V₂. Density CalculatorDensity from mass and volume, in three units. Half-Life CalculatorRemaining amount after a given time from half-life.

Construction & Home Calculators

Roofing CalculatorEstimate roof area, squares, and shingle bundles from footprint and pitch. Mulch CalculatorHow much mulch you need in cubic yards, cubic feet, and bags. Concrete CalculatorEstimate concrete volume for slabs, footings, or columns in yards, metres, and bags. Paint CalculatorGallons of paint for a room, with coats and openings. Tile CalculatorTiles needed for a floor, including waste allowance. Gravel CalculatorEstimate gravel volume in yards, tons and bags. Wallpaper CalculatorEstimate how many wallpaper rolls you'll need.

Other Calculators & Tools

Age CalculatorExact age in years, months, and days. Date CalculatorDays between two dates, or add/subtract days from a date. Time Duration CalculatorElapsed time between two times or two date-and-time values. Day of the Week CalculatorFind the weekday for any date (Zeller’s congruence). Unit ConverterConvert length, weight, temperature, and volume. Weight (Mass) ConverterConvert between kilograms, pounds, ounces, stones, grams, and more. Base64 Encoder / DecoderEncode or decode text as Base64 in your browser (no data sent away). Password GeneratorCreate strong random passwords locally with custom length and characters. GPA CalculatorGrade point average from your courses and credits. Embed Code GeneratorCreate an embed code to place a calculator on your own page. Hours Calculator (Time Card)Hours worked from clock times, plus pay. Temperature ConverterCelsius, Fahrenheit and Kelvin in one step. Dog Age CalculatorConvert dog age to human years by size. Unit Price CalculatorCompare price per unit across different sizes. Weighted GPA CalculatorCompute weighted GPA by course level. Love CalculatorEnter two names for a playful compatibility score (just for fun).

Your tools

Favourites, recently used calculators and saved results are kept in your browser on this device — nothing is sent anywhere.

Favourites

Recently used

Saved calculation history

You can copy, export (CSV), print or share any result from its calculator page.

How to use this site

Use the theme picker in the header to switch between four looks (Classic, Dark, Ocean, Forest) — your choice is remembered on this device. Each calculator page includes tools to save to favourites, copy a result, export to CSV, share a link, or print. Calculators include formula explanations and assumptions. Some tools (like the Loan Calculator) let you compare options side by side; for others, you can run the calculator again with new inputs to compare results on the same page.

These calculators are provided for general information and estimates only. Financial, health, weather, chemistry, construction, and other results may vary — for important decisions, check measurements and consult a qualified professional. No data you enter is sent to a server by these calculators; favourites, recent tools, and saved history stay in your browser on this device.

MyBMI Tools — frequently asked questions

Are these calculators free to use?

Yes. Every calculator and tool on MyBMI Tools is free, with no account, no paywall and no limit on how many times you can calculate.

Do you store the numbers I enter?

No. All calculations run in your browser with JavaScript. Your inputs are not sent to a server. Favourites, recent tools and saved history are kept in your browser's local storage on your own device, and you can clear them at any time.

How accurate are the results?

Each calculator shows the formula it uses, a worked example and its assumptions, so you can check the maths yourself. Where rounding matters (currency, percentages, unit conversions) results are rounded for display only and the underlying calculation keeps full precision.

Which calculators are available?

63 tools across seven categories: financial (mortgage, loan, compound and simple interest, auto loan, tip, discount), fitness and health (BMI, BMR, calories, ideal weight, body fat, pace, sleep, healthy weight goal), maths, weather, chemistry, construction, and everyday tools such as dates, time, units, Base64, GPA and passwords.

Can I use a calculator on my own website?

Yes — open the Embed Code Generator, choose a calculator and size, and copy the generated iframe snippet into your page.

Updated 2026–11–10. 63 calculators, all formulas documented on the page.