Free

Free Unit Converter Online

A free unit converter: length, weight, temperature, and data sizes — type a number and see every conversion at once.

Free tool · No sign-up · Private

Value

From unit

Exact conversion factors to the metre.

Tap any result card to make that unit the new input.

Private by design. Everything runs 100% in your browser — your numbers are never uploaded, stored, or sent anywhere.

About this tool

About the Unit Converter

A unit converter answers the everyday question of how much that is in the units you understand. Type a number into this free online tool and instantly see it converted across length, weight, temperature, and data storage — metric and imperial side by side. Travelers convert miles to kilometers, cooks switch cups to milliliters, students check homework, and developers translate bytes to gigabytes without mental arithmetic.

Conversions use standard international definitions, and temperature handles the tricky Celsius-Fahrenheit-Kelvin math that trips everyone up. For data sizes, the tool follows the decimal convention where 1 KB equals 1000 bytes — the standard used by storage manufacturers and network speeds — rather than the binary 1024 used by some operating systems. Everything calculates instantly in your browser with no sign-up and no data leaving your device.

How it works

Three steps to any conversion

Pick a category

Length, Weight, Temperature, or Data — tap the tab for the kind of conversion you need.

Enter a value and unit

Type the number and choose what it's in — say, 5 miles, 72 °F, or 2.5 GB. Results update as you type.

Read every result

The whole category converts at once — no second step. Tap any card to flip that unit into the input.

Good to know

Conversions done right

The details other converters get wrong.

Temperature needs formulas

Length and weight convert with a single multiplication factor. Temperature doesn't: converting °F to °C needs an offset as well as a scale ((°F − 32) × 5/9). This tool uses the real formulas, and warns you about values below absolute zero.

1024 vs 1000 for data

We use 1024-based units (1 KB = 1024 B) because that's what your OS reports. If a “1 TB” drive shows 931 GB on your computer, that's the same bytes measured two ways — 1,000,000,000,000 ÷ 1024⁴ ≈ 931 GB.

Pounds, ounces, and stones

Weight uses the international avoirdupois definitions: 1 lb = 453.59237 g and 1 oz = 28.349523125 g exactly. If you need stones (1 st = 14 lb), convert lb first and divide by 14.

Precision without noise

Results are rounded to 10 significant digits, so you see 2.54 cm for an inch — not 2.5399999999. Good enough for real work, clean enough to copy-paste.

Examples

Typical use cases

recipe.txt

US recipe: bake at 350 °F.
Enter 350, unit °F → 176.7 °C.
Your oven dial says 180 °C.
Close enough — dinner is saved.

video-upload.txt

Raw footage: 47.3 GB.
Enter 47.3, unit GB → 48,435 MB.
Upload quota is 50 GB? You're
2.7 GB under. Go live.

FAQ

Unit converter questions

Which unit categories are supported?

Four: Length (mm, cm, m, km, inches, feet, yards, miles), Weight (mg, g, kg, oz, lb), Temperature (°C, °F, K), and Data (B, KB, MB, GB, TB). Type one value and pick the input unit — every other unit in that category converts instantly.

Are temperature conversions accurate?

Yes. Temperature uses the proper formulas — °F = °C × 9/5 + 32 and K = °C + 273.15 — not simple multipliers like the other categories. If your input lands below absolute zero (−273.15 °C), the tool flags it as impossible.

Is 1 KB 1000 or 1024 bytes here?

1024 — the convention operating systems use when reporting file and disk sizes. So 1 GB = 1024 MB here. Storage manufacturers sometimes advertise 1 GB as 1,000 MB, which is why a “1 TB” drive shows up smaller in your OS.

Can I switch the input unit without retyping?

Yes. Every result card is a button — tap the unit you want and it becomes the new input, keeping the same numeric value.

Is my data private?

Completely. Conversions run in your browser with plain JavaScript — nothing is typed into a server, stored, or tracked.

How do I convert miles to kilometers?

Select length, enter your miles value, and the kilometer equivalent appears instantly alongside every other length unit.

Is 1 KB 1000 or 1024 bytes here?

1000 bytes — the decimal convention used by storage makers and network speeds. Some operating systems display 1024-based values, which is why numbers occasionally differ.

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