Stones to Tonnes
Convert stones to tonnes instantly — one stone is 0.00635029 tonnes.
| Stones | Tonnes |
|---|---|
| 1 st | 0.00635 t |
| 2 st | 0.012701 t |
| 3 st | 0.019051 t |
| 5 st | 0.031751 t |
| 10 st | 0.063503 t |
| 25 st | 0.158757 t |
| 50 st | 0.317515 t |
| 100 st | 0.635029 t |
How to use
- Enter a value in the Stones field.
- The Tonnes figure appears immediately — no button to press.
- Typing in the Tonnes field converts back to Stones the same way.
- Use the reference table for the values that come up most often.
Stones to Tonnes formula
To convert stones to tonnes, multiply by 0.00635029318.
t = st × 0.00635029318
Why this factor: the stone and the tonne are both defined against the kilogram, so dividing one definition by the other gives 0.00635029318 directly. Both definitions are set out in full below.
To go the other way, divide by 0.00635029318 — or use the Tonnes to Stones converter, which is the same calculation reversed.
Worked example
Given 2 st, multiplying by 0.00635029318 yields 0.012701 t.
2 st × 0.00635029318 = 0.012701 t
The converter above does this for any value you type, in either direction.
What is a stone?
A stone is fourteen pounds, still the customary unit for body weight in Britain and Ireland.
Definition: Fourteen avoirdupois pounds, so exactly 6.35029318 kilograms.
Where it is used: Personal body weight in the UK and Ireland, where weight is usually given as stones and pounds.
Worth knowing: Effectively unused in the United States, where body weight is quoted in pounds alone.
What is a tonne?
A tonne, or metric ton, is 1,000 kilograms — the standard unit for bulk freight and industrial quantities.
Definition: Exactly 1,000 kilograms. Accepted for use with SI but not itself an SI unit.
Where it is used: Shipping and freight, steel and cement output, vehicle masses, and carbon emissions accounting.
Worth knowing: Distinct from the US short ton (2,000 lb ≈ 907 kg) and the UK long ton (2,240 lb ≈ 1,016 kg).
Stones vs Tonnes
The stone is an imperial unit while the tonne is a metric unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many tonnes are in a stone?
One stone equals 0.00635029318 tonnes.
What is the formula to convert stones to tonnes?
Multiply the number of stones by 0.00635029318. To reverse it, divide by 0.00635029318 instead.
How do I convert tonnes back to stones?
Divide by 0.00635029318, which is the same as multiplying by 157.473044.
How many tonnes are in 10 stones?
10 st works out to 0.063503 t.
Is there anything to watch out for with stones?
Effectively unused in the United States, where body weight is quoted in pounds alone.
How is the stone defined?
Fourteen avoirdupois pounds, so exactly 6.35029318 kilograms.