Converters Calculators
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)
Unit converters
Converting between units of measurement is one of those small, constant tasks that's easy to get wrong under pressure — a misplaced factor of ten, or reaching for the wrong conversion entirely. These tools do the arithmetic exactly and show the working, so you can trust the number and understand where it came from.
The pressure converter handles the units engineers and technicians actually meet — bar and psi, the SI pascal family, atmospheres, and the mercury-column units used in vacuum and weather work. The temperature converter moves between Celsius, Fahrenheit, Kelvin, and Rankine, and the angle converter covers degrees, radians, gradians, and more. Thelength converter handles metric and imperial distances (metres, inches, feet, miles), and themass / weight converter covers grams, kilograms, ounces, pounds, and more. There are also converters forspeed (m/s, km/h, mph, knots),energy (joules, kWh, calories, BTU), anddigital storage (MB, GB, and the binary MiB, GiB). Each one turns a single value into every unit at once. More converters will join this category over time.
Exact conversions and approximate ones
It is worth knowing which of these are definitions and which are measurements, because that tells you how far to trust the last digits. An inch is exactly 2.54 centimetres, a pound is exactly 0.45359237 kilograms, and a foot is exactly 0.3048 metres. These are defined values, fixed by agreement, and every length and mass conversion here follows from them without approximation.
Others carry a physical constant and are only as good as the measurement behind them. Energy conversions involving the calorie depend on which calorie you mean — the thermochemical one is exactly 4.184 joules by definition, but older sources use slightly different values. Where a unit has competing definitions, the page says which it uses.
Mass is not weight, and other traps
A kilogram is a mass; a pound is used for both mass and force depending on context. On Earth the distinction rarely bites, which is exactly why it catches people out when it does. If you are converting for a physics problem rather than a shopping list, check whether you want pounds-mass or pounds-force — the force calculatorkeeps them separate.
Data sizes have their own version of this. A megabyte can mean 1,000,000 bytes or 1,048,576 depending on who is counting, which is why drive manufacturers and operating systems have disagreed about disk capacity for decades. The data size converter handles both the decimal (MB, GB) and binary (MiB, GiB) families and keeps them distinct rather than pretending they are the same.
Fuel economy runs backwards
Miles per gallon and litres per 100 km are not merely different units — they are reciprocal measures, so they cannot be converted by multiplying. More is better in one and worse in the other, and the relationship is a curve rather than a line. That has a real consequence: improving from 15 to 20 mpg saves considerably more fuel over the same distance than improving from 40 to 50 mpg, even though the second looks like the bigger gain.