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151+ free online calculators. Math, finance, health, conversions, timers, AI, electronics, dev tools, and much more.
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Speed Converter
MPH, KPH, knots, m/s
ConversionsArea Converter
Sq ft, sq m, acres, hectares
ConversionsVolume Converter
Gallons, liters, cups, ml
ConversionsData Storage Converter
Bytes, KB, MB, GB, TB
ConversionsTime Converter
Seconds, minutes, hours, days
ConversionsEnergy Converter
Joules, calories, BTU, kWh
ConversionsPressure Converter
PSI, bar, atm, pascal
ConversionsFuel Economy Converter
MPG, L/100km, km/L
ConversionsAngle Converter
Degrees, radians, gradians
ConversionsOhm's Law
Voltage, current, resistance, power
ElectricityPower Calculator
Watts, volts, and amps
ElectricityLED Resistor
Resistor for LED circuit
ElectricityRC Time Constant
RC circuit time constant
ElectricityElectricity Cost
Cost from watts and hours
ElectricityBattery Life
Runtime from capacity and load
ElectricitydBm to Watts
Convert dBm and watts
ElectricityFuel Cost
Fuel cost for a trip
EverydayDog Age
Dog years to human years
EverydayCat Age
Cat years to human years
EverydayPopular Calculators
General Calculator
Type expressions naturally — no buttons needed
Mortgage Calculator
Monthly payments, total interest, and amortization
BMI Calculator
Calculate your Body Mass Index
Token Estimator
Estimate LLM token count for text
Ohm's Law
Calculate voltage, current, resistance, power
Password Generator
Generate secure random passwords
Timer & Stopwatch
Countdown timer and stopwatch
Pizza Calculator
Compare pizza sizes by price per sq in
Browse by Category
Math
General, scientific, percentage, fractions, statistics
Finance
Mortgage, loans, interest, investments, retirement
Health
BMI, TDEE, calories, body fat, heart rate, sleep
Conversions
Length, weight, temperature, speed, area, volume
Timers & Clocks
Timer, stopwatch, Pomodoro, world clock
Computer & Dev
JSON, regex, Base64, UUID, passwords, hashes
Electricity
Ohm's law, resistors, capacitors, wire gauge
AI & ML
Token estimator, API costs, model sizing, metrics
Everyday
GPA, fuel, pizza, paint, concrete, pets, photography
Network
Bandwidth, subnets, CIDR, latency, WiFi, ports
Security
Password strength, JWT decoder, entropy, hashes