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326+ free online calculators. Math, finance, health, conversions, timers, AI, electronics, dev tools, and much more.
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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
Physics
Velocity, force, energy, projectile motion, waves, thermodynamics
RF & Antenna
Wavelength, path loss, VSWR, link budget, dBm, coax, noise figure
Space
Orbital mechanics, rocket equation, black holes, stellar physics
Statistics
Normal distribution, confidence intervals, probability, z-scores
Geometry
Triangles, circles, polygons, arc length, slope, and 2D shapes
401(k) Savings Calculator
Project your 401(k) balance at retirement including employer matching
FinanceMortgage Refinance Calculator
Compare your current mortgage with a refinance and find your break-even
FinanceHome Affordability Calculator
Estimate the maximum home price you can afford using the 28/36 rule
FinanceHELOC Calculator
Calculate your available HELOC line, draw-period payments, and repayment schedule
FinanceCredit Utilization Calculator
Track per-card and overall credit utilization — keep it under 30%
FinanceBra Size Calculator
Find your bra size from measurements and convert between US, UK, EU, FR, AU
HealthSpeed 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
EverydayTire Size Calculator
Compare two tire sizes — diameter, circumference, speedometer difference
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