Unit Converter

Step by step

How to convert units

Four steps, no account, no daily limit, and no advert sitting between you and the answer.

Pick what you’re measuring

Tap Length, Weight, Temperature or any of the eleven kinds of measurement along the top. Each one opens on a sensible example, so you can see how it works before you type anything.

Choose your two units

Set the units you have and the units you want from the two menus. The Swap button turns the conversion around in one tap, so centimetres to inches becomes inches to centimetres.

Type your number

Type into either box and the other one fills in as you go. Commas, fractions like 1 1/2 and heights like 5 ft 7 in are all understood, and if the tool had to interpret what you typed it says how.

Take the answer

The green button copies the answer with its unit. Every other unit of the same kind is listed underneath, each with its own copy button, along with a quick-reference table for the pair you picked.

Private by design

Why nothing you type here is sent anywhere

A unit converter sounds like the last place privacy matters — until the number is your body weight, a medicine dose, the size of a plot in a land deal, or a dimension off a client’s drawing. Most converters are ad-funded pages that load dozens of third-party scripts around the box you type into. This one does its arithmetic on your own device, and you can prove that in about ten seconds.

Nothing is uploaded

Every unit on this page is a fixed definition — an inch is 2.54 cm today and will be tomorrow — so the whole converter downloads to your browser once and needs nothing more. The number you type never enters a network request, so there is no copy of it for us to keep, lose or sell.

Nothing is saved

We deliberately do not remember what you converted, not even in your own browser’s storage, and the page never writes your number into its web address. Close the tab and it is genuinely gone — nothing for the next person on a shared computer to find.

No account, no adverts

No sign-up, no email capture, and no advert jumping around the page while you type. A converter that runs on your own machine has no running costs to recover, so there is nothing to meter and no reason to make you wait.

To be precise about what does leave your device — because “100% private” is easy to say and worth checking. Three things, none of them the number you typed:

1. The first time you convert something, this page sends one anonymous message to our counter saying “unit-converter was used”. Not your number, not the answer, not the units, nothing identifying you. It exists so the usage number in the panel is a real one rather than something we invented.
2. Google Analytics records the page view and that the tool was used, the same as on every other page of this site. It is told which kind of measurement and which two units you picked — “length, centimetres to inches” — so we know which conversions to improve. It is never told the number or the answer. Block it and the converter works exactly the same.
3. When the page first loads, the fonts it is set in are fetched from Google Fonts, which means Google sees your IP address at that moment — the same as on every other page of this site. Once the page has loaded, that request never happens again, which is why the offline test below works.

Your number is in none of them. It never enters a network request at all — and unlike a promise, that is something you can check. Turn off your wifi, reload this page and keep converting. It still works.

At a glance

Tool specifications

Kinds of measurement	11 — length, weight, temperature, area, volume, speed, time, data, fuel economy, pressure and energy
Units	105, metric, imperial and US customary, each from its legal definition (an inch is exactly 0.0254 m, a US gallon exactly 3.785411784 L)
Indian units	Tola, quintal, cent, guntha and gaj (square yard). Bigha, biswa, kanal and marla are not included, because their size varies from state to state
Two-part units	Feet + inches, pounds + ounces and stone + pounds, typed the way you would say them: `5 ft 7 in`, `5'7"` or `5 7`
US and UK measures	Listed separately and never assumed — US and UK gallons, pints, fluid ounces and mpg, plus US and metric cups
What you can type	Decimals, grouping like `1,234.5` or `12,34,567`, a decimal comma like `2,5`, fractions like `1 1/2`, scientific notation like `1e6`, and negative numbers
Precision	Calculated to 15 significant figures. Shown to 7 by default, or 2 or 4 decimal places, or the full 15. Marked = when exact and ≈ when rounded
Very large or small numbers	Shown as × 10ⁿ below 0.000001 and from 10¹⁵ up — and whenever a fixed number of decimal places would otherwise round a real value down to zero
Formula	Shown for every pair of units, including the offsets for temperature and the division for fuel economy
Currency	Not included. Exchange rates change by the minute and would need a server, which this page does not use
Where processing happens	In your browser, on your device — nothing is uploaded
Saved anywhere	No. Not on a server, not in your browser’s storage and not in the page address
Works offline	Yes, once the page has loaded, including as an installed app
Sign-up	Not required, not offered
Price	Free

Shortcuts

Popular conversions

Each one sets the converter up for that pair. Whatever number you have already typed stays as it is.

Questions

Units, answered

Is anything I type uploaded or saved?

No. Every conversion runs inside your browser using code downloaded to your device, so the number you type is never placed in a network request and never reaches us. It is not saved to your browser’s storage or written into the page address either. The simplest proof: disconnect from the internet and keep converting — it still works.

Why does the answer sometimes say ≈ instead of =?

An equals sign means the answer is exact. One inch is exactly 2.54 cm because that is how the inch is defined, so that answer gets =. The wavy sign means the true answer has more digits than are shown: 1 kilometre is about 0.6213712 miles, and the real figure keeps going. Choose Full precision under Advanced options to see up to 15 significant figures.

How do I convert my height from feet and inches to centimetres?

Choose Length, set the first unit to Feet + inches, and type your height the way you would say it: 5 ft 7 in, 5′7″, or just 5 7. That height is 170.18 cm. To go the other way, put Feet + inches in the second box instead — 170 cm comes out as 5 ft 6.93 in.

Is a gallon or a cup the same size everywhere?

No, and this catches a lot of people out. A US gallon is 3.785 litres, but a UK gallon is 4.546 litres, about 20% more. Pints and fluid ounces differ in the same way. Cups vary too: a US cup is 236.6 ml, while most recipes from India, Australia and the UK mean a metric cup of 250 ml. That is why each one is listed separately here rather than one being quietly assumed.

Why does my 1 TB hard drive only show 931 GB?

Nothing is missing — two different kinds of gigabyte are being used. Drive makers count in thousands, so 1 TB is 1,000,000,000,000 bytes. Windows counts in 1,024s and still calls the result GB, and 1,000,000,000,000 bytes divided by 1,024 three times is about 931. The 1,024-based units have their own names, GiB and TiB, and the Data converter lists both kinds.

Why isn’t km/L to L/100 km a simple multiplication?

Because one is upside down compared with the other. Kilometres per litre is distance per unit of fuel, so a higher number is better. Litres per 100 km is fuel per unit of distance, so a lower number is better. To convert you divide instead of multiply: 15 km/L is 100 ÷ 15, about 6.67 L/100 km, and 20 km/L is exactly 5. Converters that treat it as a multiplier give answers that go in the wrong direction.

Can it convert bigha, kanal or marla?

Not yet, and deliberately. A bigha in one state can be several times the size of a bigha in another, and kanal, marla and biswa vary in the same way, sometimes between districts. Any single figure would be wrong for most people, and in a land deal that is an expensive mistake. The land units that are the same everywhere are included: acre, hectare, cent (435.6 sq ft), guntha (1,089 sq ft) and gaj (a square yard, 9 sq ft).

Why is there no currency converter here?

Exchange rates change by the minute, so converting money needs today’s rates from a server. That would mean this page contacting a third party every time you used it, which would break the promise that nothing leaves your device. Every unit here is a fixed definition that never changes, so it can all be worked out on your own machine. Nopturnia funds itself through affiliate links on its product buying guides, not through these tools.

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A unit missing, or an answer look wrong?

If a conversion disagrees with another source, a unit you use isn’t here, or a local unit needs adding, tell us. The form opens with the tool already filled in, so you only have to describe what happened.

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