Convert one measurement into every unit of the category at once, with the formula in sight.
This converter covers fourteen categories, length, mass, temperature, data, time, speed, area, pressure, volume, energy, power, angle, frequency and fuel economy, and computes everything in your browser, without sending values to any server. Instead of showing a single from-to pair, it converts the value you type into every unit of the category at once, in a copyable table, and it shows the formula applied to the active pair (for example °F = °C × 9/5 + 32). Each category has one base unit (meter for length, kilogram for mass, kelvin for temperature, byte for data) and conversion happens in two steps: your value becomes the base, then the base becomes the target unit. What changes is the shape of the relation with that base: proportional (1 inch = 0.0254 m), affine, when scales have different zero points and an offset is required (Celsius and Fahrenheit), and inverse, when more of one unit means less of the other (L/100 km against km/L and mpg). The value field also accepts written queries such as "5 km to miles" or "70kg em lb", and you control decimal places, scientific notation and the thousands separator without leaving the page.
Each category defines one base unit. Conversion never jumps straight from A to B: it first takes your value to the base, then leaves the base for the target. That keeps every unit in a category comparable through a single reference point, which is also what makes it cheap to show the value in all of them at once, one calculation per unit.
What changes from unit to unit is the shape of the relation with the base. Most are proportional, a fixed factor. Temperature is affine, because Celsius, Fahrenheit and Rankine do not share a zero point, so there is an offset on top of the factor. Fuel economy is inverse: L/100 km measures fuel spent per distance while km/L measures distance gained per liter, so one is the reciprocal of the other and the direction of "better" flips. The formula shown in the tool is derived from the active pair itself, so it can never disagree with the number on screen.
Example 1, temperature: 100 °C to °F. The value becomes kelvin (100 + 273.15 = 373.15 K), then Fahrenheit (100 × 1.8 + 32 = 212 °F). Boiling water at 100 °C is exactly 212 °F, and the 32-degree offset is precisely what stops you from just multiplying by 1.8.
Example 2, data: 1 GB to GiB. A decimal gigabyte is 1,000,000,000 bytes; a gibibyte is 1024³ = 1,073,741,824 bytes. Dividing, 1 GB is about 0.9313 GiB, which is why a "1 TB drive" shows up as roughly 931 GiB in your system.
Example 3, fuel: 10 L/100 km equals 10 km/L and about 23.52 mpg (US). Note that cutting consumption from 10 to 5 L/100 km doubles the range, from 10 to 20 km/L. Because the relation is inverse, the gap between 5 and 6 L/100 km is worth far more fuel per year than the gap between 15 and 16 L/100 km.
It fits cooking (cups, tablespoons and milliliters), travel (miles, kilometers, °F and °C), tech (bits, bytes, download rates, frequency in Hz), light engineering (pressure in bar, psi or atm; energy in kWh, kcal or BTU; power in hp, PS or kW) and comparing car specs published in L/100 km, km/L or mpg. Because everything runs locally, there is no usage limit and no data leaves your device.
The limit is floating-point precision: the result is rounded for display while keeping about 12 significant figures, so chained conversions can accumulate small differences. The decimals control changes only the display, never the calculation. US kitchen units (cup, tbsp) follow the US standard, which differs from the British one, and the UK gallon is larger than the US gallon, which is why mpg (UK) and mpg (US) are listed separately. "Month" and "year" use average durations (a Julian year of 365.25 days), so they do not replace a real calendar count.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
<iframe
src="https://jkit.tools/embed/en-US/unit-converter"
width="100%"
height="600"
style="border:0"
loading="lazy"
title="Unit Converter"
></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
There are fourteen categories: length, mass, temperature, data, time, speed, area, pressure, volume, energy, power, angle, frequency and fuel economy. Each one holds several units, from nanometer to nautical mile, from bit to exbibyte, from pascal to atmosphere, and conversion only happens between units of the same kind, because turning meters into seconds makes no sense.
m = km × 1000| Unit | Value | Actions |
|---|---|---|
| 1E12 | ||
| 1E9 | ||
| 1,000,000 | ||
| 100,000 | ||
| 1,000 | ||
| 1 | ||
| 39,370.079 | ||
| 3,280.84 | ||
| 1,093.613 | ||
| 0.62137119 | ||
| 0.5399568 |
Conversion is mathematical and local. Nothing is sent to a server.