PTBox

Unit Converter (Length / Mass / Temperature / Data / and more)

Online unit converter covering 10 common categories: length (m / ft / Chinese chi / light-year, 16 units), mass (g / lb / Chinese jin, 11 units), volume, area (incl. acre / Chinese mu), temperature (Celsius / Fahrenheit / Kelvin / Rankine), time, speed (incl. Mach and speed of light), data storage (both SI and IEC — KB vs KiB clearly separated), angle, pressure. Enter a value and a source unit; all other units in the same category are computed live. Click any row to make that unit the new source. Runs entirely in the browser.

Conversions (click any row to use that unit as source)
Nanometer (nm)
1,000,000,000
Micrometer (μm)
1,000,000
Millimeter (mm)
1,000
Centimeter (cm)
100
Meter (m)
1
Kilometer (km)
0.001
Inch (in)
39.370079
Foot (ft)
3.2808399
Yard (yd)
1.0936133
Mile (mi)
0.00062137119
Nautical mile (nmi)
0.0005399568
Chinese Li (里)
0.002
Chinese Zhang (丈)
0.3
Chinese Chi (尺)
3
Chinese Cun (寸)
30
Light-year (ly)
1.0570e-16

All conversions run locally — no network needed. Temperature uses dedicated formulas (preserving offsets); other categories use SI conversion factors. Very large / small results switch to scientific notation automatically.

Usage

Local unit converter covering 10 categories: length / mass / volume / area / temperature / time / speed / data storage / angle / pressure. Useful for both programmer scenarios (milliseconds, bytes, KB vs KiB) and everyday ones (Fahrenheit, acres, Chinese jin / mu).

UI pattern: enter a value, pick a source unit — see live conversions to every other unit in that category. Click any row to make that unit the new source while keeping the same physical quantity.

Key design: the data-storage category separates SI decimal (KB = 1000 B, MB = 10⁶ B) from IEC binary (KiB = 1024 B, MiB = 1024² B) explicitly — the difference between a 1 TB drive and 1 TiB is nearly 10%. Temperature uses dedicated non-linear formulas (with offsets), not simple ratios.

All computation runs in the browser — no network requests, no data leaves your device.

Use cases

Overseas purchases

Convert lb / oz / ft / in on US listings into the kg / cm you know before deciding.

Verifying disk size

A 1 TB drive shows up as 931 GB because manufacturers use SI decimal (1000) while OSes use IEC binary (1024). This tool shows both side by side.

Travel & cooking recipes

Fahrenheit, gallons, feet for height, US cups / teaspoons for ingredients.

Engineering & STEM homework

Pressure (Pa / bar / psi), energy, angle (radian / degree) — pro-grade conversions.

FAQ

KB vs KiB — and why does a 1 TB drive show as 931 GB?

Drive makers use decimal 1 TB = 10¹² bytes; Windows reports binary 1 TiB = 2⁴⁰ bytes — about 10% gap. This tool lists KB/MB/GB (SI) and KiB/MiB/GiB (IEC) separately so you see both at once.

Why can't temperature be a simple ratio?

Temperature is a non-linear mapping with offsets — 0°C ≠ 0°F (32 apart). The tool uses proper formulas: °F = °C × 9/5 + 32, K = °C + 273.15, °R = (°C + 273.15) × 9/5.

Is my data safe?

Everything is computed locally — formulas and factors are bundled in the frontend JS. No network requests; inputs and results never leave your device.

Does it support Chinese-system units (jin / mu / chi)?

Yes — jin / liang / qian for mass, mu for area, li / zhang / chi / cun for length.

Why do some results show as 1.234e+5?

Values above 10¹⁵ or below 10⁻⁴ switch to scientific notation to keep the row readable. The copy button on the right copies the full value.

Crypto or stock units?

Not supported — this tool covers physical units only. Use the Currency Converter for money.

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