Free online calculators with clear explanations
Health
View all (18)BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Enter your weight and height to see where you fall on the WHO weight cat…
HealthCalorie Calculator
Estimate how many calories you need per day based on age, weight, height, and activity.…
HealthOvulation Calculator
Estimate your ovulation day and fertile window from the first day of your last period and your average cycle length. Use…
HealthPeriod Calculator
Predict your next period — and the two after that — from the first day of your last period and your average cycle length…
HealthPregnancy Due Date Calculator
Estimate a due date by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). Ultrasound and c…
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…
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12 more calculators
Finance
View all (14)Compound Interest Calculator
See how your savings grow when interest earns interest over time.…
FinanceCurrency Converter
Enter an amount, pick a source and target currency, and see the converted value with the cross-rate and rate date. Rates…
FinanceLoan Calculator
Estimate your monthly payment for personal or auto loans.…
FinanceVAT Calculator
Calculate VAT or sales tax both ways: tax-exclusive → inclusive, or extract net and tax from an inclusive price. Presets…
FinanceSolar Panel Payback Calculator
Enter installed cost, incentives, system size, peak sun hours, and your electricity rate to estimate how many years unti…
FinanceTake-Home Pay Calculator
Convert gross annual pay to estimated net take-home after progressive income tax and optional payroll/social deductions …
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8 more calculators
Math
View all (20)Percentage Calculator
Find what percentage one number is of another, or calculate increases and decreases.…
MathFraction Calculator
Work with two fractions: choose an operation, enter numerators and denominators, and get a simplified result plus a deci…
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
Enter pixel or print dimensions to simplify a ratio, scale one side to match a target ratio, or size a crop (and letterb…
MathCombination Calculator
Use this calculator when order does not matter — committee picks, lottery choices, product bundles, and menu pairings.…
MathPermutation Calculator
Use this calculator when order matters — rankings, seat assignments, PIN patterns, route sequences, and scheduling arran…
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14 more calculators
Everyday
View all (17)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
Quickly calculate how much to tip and the total per person when dining out.…
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…
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11 more calculators
Auto
View all (12)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…
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6 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 at which air becomes saturated so moisture can condense as dew, frost, or fog.…
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
Use this calculator to estimate practical tractor field capacity and how long a field job should take.…
Construction & Home Improvement
View all (11)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…
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5 more calculators