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Unit Converter · Length, Mass and Temperature

Online conversion across length (m/cm/mm/km/in/ft/yd/mi), mass (kg/g/t/lb/oz) and temperature (°C/°F/K). Enter a value to see the full matrix across all units in the same category. Runs locally in your browser.

Overview

Unit conversion is one of the most frequent everyday tool needs. This first version covers the three highest-volume categories: length (m / cm / mm / km / in / ft / yd / mi), mass (kg / g / t / lb / oz) and temperature (°C / °F / K). Enter any value and source unit to see the target conversion plus the full cross-unit matrix. Runs entirely locally.

How to use

  1. Pick a category (length, mass or temperature).
  2. Enter a value, then pick source and target units.
  3. The main result shows the target value; the matrix below shows conversions across every unit in the category.
  4. Switching category auto-resets source/target units to that category's defaults.

Formula

1) Linear (length/mass): each unit has a factor relative to the base unit (m or kg).
   value_B = value_A × factor_A / factor_B
   1 in = 0.0254 m, 1 lb = 0.45359237 kg, 1 mi = 1609.344 m, etc.
2) Temperature (nonlinear):
   C→F: C·9/5+32, F→C: (F−32)·5/9
   C→K: C+273.15, K→C: K−273.15
   F↔K: chain through C

Common scenarios

Scenario 1 · How many inches in 1 m?

1 m = 39.3701 in. Anchor 1 in ≈ 2.54 cm for quick mental estimation.

Scenario 2 · 100 °F in °C

(100 − 32) × 5/9 ≈ 37.78 °C — that's a hot day in most weather apps.

Scenario 3 · 1 kg in pounds

1 kg ≈ 2.2046 lb. Handy for overseas shipping and medical reports.

FAQ

What's the precision?

Computations use IEEE 754 double precision; display keeps up to 6 significant figures with locale-aware thousands/decimal separators. Extreme values fall back to scientific notation.

Why isn't temperature linear?

Linear conversions are just a scale factor. Temperatures differ in both unit size *and* zero point (°C zero = water freezing, °F zero is offset, K zero = absolute zero), so conversion needs both shift and scale.

Why not include area, volume, speed?

This first version focuses on the highest-traffic three. Area, volume, time, speed, data storage and currency will arrive in later waves.

Do you support SI, imperial and US customary?

Length covers SI and US/imperial; mass covers SI and avoirdupois (lb/oz); temperature uses °C/°F/K. The "tonne" here is metric (1000 kg); US short ton / UK long ton can be added on request.

Does this tool upload data?

No. All conversions run locally in your browser; no network requests.

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