Comprehensive Unit Converter (Pressure, Energy, Power & more)

Overview

A precise converter for the nine measurement families the everyday converters skip: pressure, energy, power, force, frequency, angle, torque, density, and fuel economy. Every conversion runs from exact SI factors - 1 atmosphere is exactly 101 325 pascals, 1 electronvolt is exactly 1.602176634 x 10^-19 joules since the 2019 SI revision - and the result table shows your input in every unit of the family at once.

How It Works

Pick a category, type a value, choose the from and to units, and the result appears live. A full table below shows the same value converted into every other unit in that category, each row click-to-copy. The swap button flips the direction instantly, and the fuel-economy category handles litres-per-100-km correctly as the inverse axis it is.

Step-by-Step Usage Guide

1. Choose the measurement family that matches your quantity.
2. Enter the value and select the unit you have; pick the unit you want.
3. Read the targeted result, or scan the all-units table for the full picture.
4. Click any row to copy that conversion.

Technical Specifications & Standards

Every unit is defined by its exact relationship to the SI base, and the differences matter. Pressure: the pascal is N/m^2, the atmosphere is exactly 101 325 Pa by definition, the torr is exactly 1/760 of that, and psi comes from the international avoirdupois pound - 4.448 221 615 260 5 newtons per pound-force times the square inch. Energy: the thermochemical calorie is exactly 4.184 J (food 'calories' are kilocalories), the watt-hour is exactly 3 600 J, and the electronvolt became an exact SI value of 1.602 176 634 x 10^-19 J with the 2019 SI redefinition that fixed e, h, k, and N_A. Power: metric horsepower is exactly 735.498 75 W (75 kgf-m/s) while mechanical horsepower is 550 foot-pounds per second = 745.699 871 582 W - close, but 1.4% apart, which is why the labels matter on engine specifications. Fuel economy is the interesting special case: km/L and MPG are distance-per-volume, while L/100 km is volume-per-distance, so it inverts rather than scales - 7 L/100 km is about 14.3 km/L, not 0.14. The converter models each unit with explicit to-base and from-base functions, so inverse units compose correctly.

Targeted Use Cases

• Converting tyre pressures, boiler ratings, and HVAC specs between psi, bar, and kPa.
• Comparing appliance energy use in kWh against joules or BTUs in a physics or engineering report.
• Translating engine torque between newton-metres and pound-feet for a spec sheet.
• Comparing car fuel economy between a European L/100 km figure and a US MPG figure - correctly, including the inverse axis.

Notes & Gotchas

• Watch the horsepower flavour: metric and mechanical horsepower differ by about 1.4%, enough to matter in specifications.
• Distinguish energy from power: kWh is energy, kW is power - a 3 kW heater running an hour uses 3 kWh.
• For fuel economy, lower L/100 km is better but higher MPG is better - the inverse relationship is easy to misstate.
• Use the all-units table as a sanity check: if one converted value looks off by ~10x, you probably picked the wrong prefix.

Frequently Asked Questions