CalculatorCentrum
Simple, focused calculators for everyday engineering and math.
CalculatorCentrum is a collection of free, focused calculators covering electronics, IoT, physics, maths, finance, health, home and DIY, colour, and unit conversion. Each one updates live as you type and explains the formula behind the answer with a worked example — so you can check the result, not just copy it.
Every formula here is checked when the site is built: the maths lives in modules with assertions attached, and a wrong constant fails the build rather than reaching you. The site is written and maintained by Arthur Kingsfield, an electronics engineer.
Electronics
Calculators for circuits, components, and electronic design.
Basics & passives
Timing & filters
AC, RF & signal levels
Power & amplifiers
PCB & wiring
Sensors & temperature
IoT
Calculators for battery-powered, wireless, and low-power IoT devices.
Color
Converters and pickers for web and design colors.
Converters
Unit converters for pressure and other everyday quantities.
- Pressure Converter (bar, psi, kPa, atm…)
- Temperature Converter (°C, °F, K, °R)
- Angle Converter (degrees, radians, gradians)
- Length Converter (m, cm, inch, ft, mile…)
- Mass / Weight Converter (kg, g, lb, oz…)
- Speed Converter (m/s, km/h, mph, knots)
- Energy Converter (J, kWh, cal, BTU…)
- Data Size Converter (MB, GB, MiB, GiB…)
- Volume Converter (litres, gallons, cups, m³)
- Area Converter (m², ft², acres, hectares)
- Power Converter (W, kW, hp, BTU/h)
- Time Converter (seconds, hours, days, years)
- Frequency Converter (Hz, kHz, MHz, RPM)
- Fuel Economy Converter (mpg ↔ L/100km)
- Number Base Converter (binary, hex, decimal, octal)
- Roman Numeral Converter (I, V, X, L, C, D, M)
Math
Geometry and everyday math calculators.
- Triangle Solver (law of sines & cosines)
- Right Triangle Calculator (Pythagorean theorem)
- Circle Calculator (area, circumference, radius)
- Trigonometry Calculator (sin, cos, tan)
- Quadratic Equation Solver (ax² + bx + c)
- Statistics Calculator (mean, median, mode, SD)
- Area Calculator (rectangle, circle, triangle…)
- Volume Calculator (box, cylinder, sphere, cone)
- Fraction Calculator (add, subtract, multiply, divide)
- GCD & LCM Calculator (greatest common divisor)
- Ratio Calculator (simplify and solve proportions)
Physics
Calculators for heat, energy, and other everyday physics.
- Heat Energy Calculator (Q = mcΔT)
- Density Calculator (ρ = m/V)
- Force Calculator (F = ma)
- Kinetic Energy Calculator (½mv²)
- Speed, Distance & Time Calculator
- Free Fall Calculator (drop height, time, impact speed)
- Work & Power Calculator (W = Fd, P = W/t)
- Momentum Calculator (p = mv)
- Potential Energy Calculator (PE = mgh)
- Pendulum Calculator (period and length)
- Projectile Motion Calculator (range, height, flight time)
- Terminal Velocity Calculator (with air resistance)
- Acceleration Calculator (SUVAT equations)
- Gravitational Force Calculator (Newton's law)
- Half-Life Calculator (radioactive decay)
Health
Everyday health, body, and date calculators.
- BMI Calculator (body mass index)
- Calorie & BMR Calculator (Mifflin–St Jeor)
- Ideal Weight Calculator (Devine, Robinson, Miller)
- Age Calculator (exact years, months, days)
- Date Difference Calculator (days between dates)
- Running Pace Calculator (min/km and min/mile)
- IV Drip Rate Calculator (gtt/min and mL/h)
Home & DIY
Work out how much material a job needs — and how much of it to actually buy.
Finance
Calculators for loans, interest, and everyday personal finance.
- Loan Calculator
- Compound Interest Calculator
- Simple Interest Calculator
- Percentage Calculator
- VAT Calculator (add or remove sales tax)
- Savings Goal Calculator
- Mortgage Calculator (payment & amortization)
- Tip Calculator (with bill splitting)
- Discount Calculator (sale price and savings)
- Salary Calculator (hourly to annual)
- Inflation Calculator (purchasing power over time)
- Profit Margin, Markup & ROI Calculator