Unit Conversion
Convert between common length, weight and temperature units.
How to use the Unit Conversion
The Unit Conversion is free and runs entirely in your browser — no sign-up, and nothing you enter leaves your device. It opens pre-filled with a realistic example, so you can see how it works before replacing any figure with your own; the results update as you type. Press Calculate to refresh the result panel, or Reset to return to the example.
The inputs it asks for:
- Category — choose one — Length, Weight, Temperature.
- Value — a number.
- From Unit — choose from 12 options (Meters, Kilometers, Feet, …).
- To Unit — choose from 12 options (Meters, Kilometers, Feet, …).
The formula
Each category converts through a base unit. Length passes through metres and weight through kilograms — multiply into the base, then divide into the target. Temperature isn't a simple ratio, so it converts via Celsius:
Length/Weight: Result = Value × (base_from ÷ base_to)
Temperature: convert to Celsius, then to the target scale- base_from / base_to
- each unit's size in the base unit (metres or kilograms)
Length and weight are linear (a simple ratio), but temperature scales have different zero points — 0 °C isn't 0 °F — so they can't be done by ratio and route through Celsius. Converting between unrelated categories (say metres to kilograms) is rejected rather than silently mishandled.
Worked example
Using the example values — Category Length, Value 10, From Unit Miles, To Unit Kilometers — the Unit Conversion returns a 10 mi = of 16.0934 km.
Prefer your own numbers? Change any field above and this recomputes instantly.
Key terms
- Base unit
- The reference each category converts through (metre for length, kilogram for weight).
- Linear conversion
- A straight multiply-by-ratio, valid for length and weight.
- Temperature offset
- The reason °C↔°F needs addition, not just scaling (freezing is 0 °C = 32 °F).
Frequently asked questions
Why can't I convert metres to pounds?
They measure different things (length vs mass), so there's no valid conversion. The calculator flags cross-category conversions instead of returning a meaningless number.
Why is temperature handled differently?
Temperature scales have different zero points, so you can't just multiply by a ratio. Converting through Celsius applies the right offset and scaling.
How precise are the factors?
It uses standard definitions (1 inch = 0.0254 m exactly, 1 lb = 0.453592 kg). Results are rounded for display but computed at full precision.