Free online calculators with clear explanations
Health
BMI Calculator
Enter your weight and height to see your BMI, category, and a healthy weight range for your height.…
HealthCalorie Calculator
Estimate daily calorie needs from age, sex, height, weight, and activity using the Mifflin–St Jeor equation, then use th…
HealthOvulation Calculator
Estimate your ovulation day and fertile window from the first day of your last period and your average cycle length.…
HealthPeriod Calculator
Enter the first day of your last period and your usual cycle length. We’ll show your next three periods, ovulation and f…
HealthPregnancy Due Date Calculator
Estimate your due date from last period, conception, IVF transfer or ultrasound dating. See how far along you are, trime…
HealthPregnancy Test Calculator
Estimate when a home urine pregnancy test is most likely to work from your last period start and average cycle length. T…
View all
12 more calculators
Finance
Compound Interest Calculator
See how savings or investments grow when interest earns interest. Add regular deposits to see the full picture.…
FinanceLoan Calculator
Estimate the fixed monthly payment on a personal or auto-style loan from the amount, rate and term. Compare terms and se…
FinanceAuto Loan Calculator
Price a vehicle loan: subtract down payment and trade-in from the car price to get the amount financed, then see monthly…
FinanceTake-Home Pay Calculator
Enter gross annual income and filing status to estimate monthly take-home after federal income tax and employee FICA. Op…
FinanceIncome Tax Calculator
Enter annual income and filing status to estimate federal income tax, your effective and marginal rates, and how each br…
FinanceInflation Calculator
Compare purchasing power across years with approximate CPI annual averages, or project how today’s amount changes at a c…
View all
9 more calculators
Math
Percentage Calculator
Find a percentage of a number, what percent one number is of another, or the result of adding or subtracting a percentag…
MathFraction Calculator
Add, subtract, multiply or divide two fractions or mixed numbers. Get the simplified answer, its decimal and percent, an…
MathMixture / Dilution % Calculator
Choose what you already know: dilute a stronger solution to a target %, find the final strength after adding diluent, or…
MathAspect Ratio / Crop Calculator
Simplify a ratio from pixel dimensions, scale one side to match a target ratio, or work out the crop or letterbox needed…
MathCombination Calculator
Count combinations when order doesn’t matter, such as committee picks, lottery draws or product bundles. Compare with pe…
MathPermutation Calculator
Count arrangements when order matters, such as rankings, seating, PINs and anagrams. Choose standard, repeated, circular…
View all
14 more calculators
Everyday
Age Calculator
Find your chronological age in years, months, and days from any birth date — plus total weeks and days lived. Useful for…
EverydayTip Calculator
Calculate tip amount from bill and tip percent, then optionally split the total per person when dining out. Adjust for l…
EverydayLuggage Size Calculator
Measure your bag’s outside length, width, and height (wheels and handles included), pick your airline from the list — in…
EverydaySplit Bill Calculator
Enter the bill, tip percentage, tax percentage, and party size. Get a clear breakdown and what each person owes when spl…
EverydayShoe Size Converter
Convert adult shoe sizes across major systems and learn how to measure your feet properly. Results are estimates — brand…
EverydayCooking Converter
Switch between kitchen volume units, or convert a volume of a named ingredient to grams — densities differ, so weight al…
View all
11 more calculators
Auto
Trip Fuel Cost Calculator
Enter trip distance, your car’s fuel economy, and the price at the pump. See how much fuel you need and what the trip wi…
AutoBoat Fuel Burn Calculator
Enter engine horsepower, fuel type, and load to estimate burn rate. Add hours underway, pump price, and tank size to see…
AutoPower-to-Weight Calculator
Enter peak power and vehicle weight (curb or with driver). Compare cars with hp/tonne, kW per kilogram, and imperial hp/…
AutoRPM ↔ Speed Calculator
Enter transmission gear ratio, final drive, and tire diameter. Convert RPM → speed or speed → RPM to estimate cruise rev…
AutoGear Ratio Calculator
Compute a gear ratio from drive and driven tooth counts, multiply by final drive for overall ratio, or compare two gears…
AutoQuarter Mile Calculator
Enter horsepower and vehicle weight (with driver). Get a ballpark 1/4-mile ET and trap speed from classic power-to-weigh…
View all
5 more calculators
Weather
Temperature Converter
Convert air, oven, or science temperatures between Celsius, Fahrenheit, and Kelvin using the standard linear relationshi…
WeatherHeat Index Calculator
Estimate the heat index: how hot it feels when humidity slows sweat evaporation. Based on the US National Weather Servic…
WeatherWind Chill Calculator
Estimate wind chill — how cold exposed skin feels when wind speeds up heat loss. Uses the modern North American (NWS/MSC…
WeatherDew Point Calculator
Find the dew point — the temperature where air becomes saturated so moisture can condense as dew or fog. Use it with tem…
Real estate
Mortgage Calculator
Estimate a fixed-rate mortgage payment from home price, down payment, interest rate, and term. Optionally add property t…
Real estateRent vs Buy Calculator
See how a fixed-rate mortgage payment stacks up against monthly rent for the same housing choice. A first-pass cash-flow…
Heavy equipment
Dump Truck Hauling Calculator
Estimate how much material a dump truck can haul per hour, per day, or per unit cost using payload, fill factor, cycle t…
Heavy equipmentWheel Loader Production Calculator
Estimate how much material a wheel loader can move per hour, per day, or per unit cost using bucket capacity, fill facto…
Heavy equipmentExcavator Production & Cost Calculator
Enter bucket capacity, fill factor, cycle time, and job efficiency to estimate production, or switch to cost mode for ho…
Heavy equipmentTractor Field Capacity Calculator
Estimate practical tractor field capacity and how long a field job should take from width, speed, and field efficiency —…
Construction & Home Improvement
HVAC BTU / Room Sizing Calculator
Enter room dimensions and a few building factors to estimate the BTU/h load for a window AC, mini-split, or heating unit…
Construction & Home ImprovementConcrete Calculator
Enter dimensions for your concrete project, choose the shape, and instantly get the volume in cubic metres and cubic yar…
Construction & Home ImprovementConcrete Bag Calculator
Choose the pour shape, enter dimensions, select a bag size (or custom yield), and get the bag count to order — including…
Construction & Home ImprovementDrywall Calculator
Enter room dimensions or a measured board area, choose sheet size and waste, and get sheets to order plus rough fastener…
Construction & Home ImprovementPaint Calculator
Choose the surface shape, enter dimensions, coats, and paint coverage to estimate total paint needed and number of cans …
Construction & Home ImprovementFlooring Calculator
Enter room size and either plank details or the coverage printed on the carton, add waste for cuts, and get how many pla…
View all
5 more calculators
Faith & calendar
Prayer Times Calculator
This page asks for your location to fill coordinates and timezone, then shows Fajr, sunrise, Dhuhr, Asr, Maghrib, and Is…
Faith & calendarQibla Direction Calculator
Allow location so we can calculate the great-circle bearing to the Kaaba, then enable the compass and turn until the Qib…
Faith & calendarHijri–Gregorian Date Converter
Choose a direction, enter a Gregorian or Hijri date, and see the matching civil date. Results use the common tabular (ar…
Faith & calendarEaster & Orthodox Easter Date Calculator
Enter a year and choose Western Easter, Orthodox Easter, or both. Results use the standard computus algorithms churches …
Faith & calendarRamadan Fasting Times Calculator
Allow location to fill coordinates and timezone, then see when to stop Suhoor and when to break the fast. Switch to the …