Free Online Calculators

Calculate your Body Mass Index from height and weight, see which WHO category you fall into (underweight, normal, overweight or obese) and get the healthy weight range for your height.

Estimate your daily calorie needs with the Mifflin-St Jeor equation, then see maintenance, cutting and bulking targets plus a macro split for protein, carbs and fat.

Work out monthly mortgage payments with equal-principal-and-interest or equal-principal schedules, see total interest, an amortization table and how prepayment shortens your term.

Compare equal-payment and equal-principal loan schedules, reverse-solve the rate you are really paying from a monthly payment, and simulate extra payments and biweekly plans.

Project your retirement pension from current savings, monthly contributions, expected returns and retirement age — see the monthly income your nest egg can support.

Estimate your baby's due date from the last menstrual period, conception date, IVF transfer day or an early ultrasound, with current gestational age and key prenatal milestones.

Calculate exact age in years, months, weeks, days, hours and seconds, plus the day of the week you were born and days until your next birthday.

A full scientific calculator in your browser: trigonometry, logarithms, powers, roots, constants and expression history — no download required.

All percentage calculations in one place: X% of Y, X is what percent of Y, percentage increase or decrease, and reverse percentages — with the formula shown for every result.

Project investment growth with compound interest and optional regular contributions, compare against simple interest and inflation-adjusted real returns.

Calculate the final price after single or stacked discounts, how much you save, and the equivalent total discount of multiple successive offers.

Add, subtract, multiply and divide fractions with automatic simplification, mixed-number conversion and step-by-step working shown for every operation.

Compute population and sample standard deviation, variance, mean, median, mode and quartiles for any data set, with the full calculation table.

Find the greatest common divisor and least common multiple of two or more integers using the Euclidean algorithm, with prime factorization shown.

Add or subtract hours, minutes and seconds, convert between time units and calculate durations across midnight — built for timesheets and planning.

Calculate your grade point average on the 4.0 scale from course credits and letter grades, and see what grades you need next term to reach a target GPA.

Compute permutations (nPr), combinations (nCr) and list all arrangements, with repetition options and the factorial formula behind each result.

Estimate monthly car payments from vehicle price, down payment, term and APR, compare flat-rate dealer financing with bank amortized loans, and see the full on-the-road cost.

Convert between 100+ units of length, weight, temperature, area, volume, speed, pressure and data size — with conversion tables and reference comparisons.

Find the best time to fall asleep or wake up based on 90-minute sleep cycles, so you wake between cycles feeling refreshed instead of groggy.

Free online math calculators for algebra, statistics, number theory and everyday arithmetic — from quadratic equations and matrices to percentages, fractions and prime factorization, each with step-by-step formulas.

Geometry calculators for area, volume, perimeter and angles of every shape — circles, triangles, cylinders, spheres and more, with formulas, worked examples and diagrams.

Personal finance calculators for loans, mortgages, savings, retirement and taxes. Compare repayment plans, project compound growth and plan your budget with clear, transparent math.

Evidence-based health calculators — BMI, daily calories, body fat, pregnancy due date, heart-rate zones and clinical scores — following international medical standards.

Training and performance calculators for runners, lifters and cyclists: pace, VO2 max, one-rep max, calories burned and race predictions based on published exercise-science formulas.

Car ownership calculators — auto loans, fuel costs, tire size comparison, EV charging and trip planning — so you know the real cost before you buy or drive.

Developer and IT calculators: subnetting, bandwidth and download time, number base conversion, password strength and storage sizing, with bitwise-level explanations.

Physics calculators for mechanics, thermodynamics, waves and electromagnetism — kinetic energy, projectile motion, Ohm's law and more, all derived from standard formulas with worked examples.

Study calculators for students: GPA and grade conversion, test score projection, exam time planning and statistics helpers for coursework and research.

Just-for-fun tools: dice rollers, random pickers, age on other planets, name generators and curiosities like the birthday paradox — instant results, zero signup.

Chemistry calculators for molar mass, solution concentration, gas laws, pH and reaction stoichiometry — ideal for lab prep, homework and quick checks.

Everyday life calculators: clothing and shoe sizes, cooking conversions, paint and fabric estimates, sleep planning and household budgeting helpers.

Building and renovation calculators: concrete volume, rebar spacing, roof pitch, drywall sheets and material takeoffs — plan quantities and costs before you build.

Kitchen calculators: recipe scaling, oven temperature conversion, ingredient substitutions, coffee ratios and meat cooking times for consistent results.

Music theory and production calculators: note frequencies, interval ratios, delay and reverb timing, tempo matching and audio file size estimates.

Photography calculators: depth of field, exposure triangle math, hyperfocal distance, print resolution and timelapse shot planning.

Electrical engineering calculators: Ohm's law, resistor color codes, voltage drop, transformer sizing and LED resistor selection with circuit explanations.

Date and time calculators: days between dates, age in years and months, working-day counts, time zone differences and countdowns to any event.

Fast unit converters for length, weight, temperature, area, volume, speed and data size — with conversion tables, formulas and real-world reference points.

Mechanical, civil and electrical engineering calculators: beam stress, gear ratios, flow rates, heat transfer and material properties for design and verification.

Business and SaaS metrics calculators: break-even, margins, CAC and LTV, runway, markup and pricing models to keep your unit economics honest.

Farm and garden calculators: seeding rates, fertilizer application, livestock feeding, pond volume and yield estimates tuned to international units.

Travel calculators: jet lag adjustment, fuel and toll costs, currency and unit conversions on the road, luggage allowance and trip budgeting.

Pet care calculators: dog and cat age conversion, food portions, medication dose ranges by weight and breeding timelines, following veterinary guidance.

Craft and DIY calculators: yarn and fabric estimates, resin volume, candle wax, soap batch sizing and pattern scaling for makers.

Environmental calculators: carbon footprint, solar panel output, rainwater harvesting, energy savings and emissions comparisons for greener decisions.