Mass Converter

Convert units in the mass converter category with fast, accurate online tools.

About mass units

Mass quantifies matter. The SI base unit is the kilogram (kg), defined via Planck’s constant since 2019.

Browse common units in this category and learn where they are typically used.

Gram (g) (g)
A gram is 1/1000 kg; ubiquitous in cooking, medicine, and lab work.
Kilogram (kg) (kg)
The kilogram is the SI base unit of mass, defined by Planck’s constant since 2019.
Long ton (UK) (lt)
Long ton (UK) is a mass unit used to compare weight-related values in everyday, scientific, or technical contexts.
Milligram (mg) (mg)
A milligram is 1/1,000,000 kg; used in pharmaceuticals and micro-dosing.
Ounce (oz) (oz)
An ounce is 1/16 lb, ≈28.35 g. Note: troy ounce is different (~31.1 g).
Pound (lb) (lb)
A pound is exactly 0.45359237 kg (avoirdupois system).
Slug (slug)
Slug is a mass unit used to compare weight-related values in everyday, scientific, or technical contexts.
Stone (st) (st)
A stone is 14 lb (~6.35 kg), still used for body weight in the UK/Ireland.
Tonne (t) (t)
A tonne (metric ton) is 1,000 kg, the default in shipping and manufacturing.

Start with some of the most frequently used conversions in this category.

Open a few ready-made examples for common real-world conversions.

Is mass conversion exact?

Many conversions are exact by definition (e.g., 1 in = 25.4 mm, 1 ft = 0.3048 m).

Can I share a specific result?

Yes. Every converter has a clean, shareable URL like /convert/meter-to-foot/2.5.

Explore other measurement categories available on MeasureCalc.