Ounces to Tonnes
Type a value in either box to convert between ounces and tonnes. The factor is 2.83495e-05.
| Ounces | Tonnes |
|---|---|
| 1 oz | 2.83495e-05 t |
| 2 oz | 5.6699e-05 t |
| 3 oz | 8.50486e-05 t |
| 5 oz | 0.000142 t |
| 10 oz | 0.000283 t |
| 25 oz | 0.000709 t |
| 50 oz | 0.001417 t |
| 100 oz | 0.002835 t |
How to use
- Enter a value in the Ounces field.
- The Tonnes figure appears immediately — no button to press.
- Typing in the Tonnes field converts back to Ounces the same way.
- Use the reference table for the values that come up most often.
Ounces to Tonnes formula
Converting ounces to tonnes is a single multiplication by 2.83495231e-05.
t = oz × 2.83495231e-05
Why this factor: the ounce and the tonne are both defined against the kilogram, so dividing one definition by the other gives 2.83495231e-05 directly. Both definitions are set out in full below.
To go the other way, divide by 2.83495231e-05 — or use the Tonnes to Ounces converter, which is the same calculation reversed.
Worked example
Start with 25 oz. Multiply by 2.83495231e-05 to get 0.000709 t.
25 oz × 2.83495231e-05 = 0.000709 t
The converter above does this for any value you type, in either direction.
What is an ounce?
An ounce is one sixteenth of a pound, used for small weights in the US.
Definition: Exactly 28.349523125 grams — one sixteenth of the international avoirdupois pound.
Where it is used: Food packaging, postal weights, and coffee and spice quantities in the US.
Worth knowing: Not the same as a fluid ounce, which measures volume. Also distinct from the troy ounce (31.103 g) used for gold and silver.
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).
Ounces vs Tonnes
The ounce 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 an ounce?
One ounce equals 2.83495231e-05 tonnes.
What is the formula to convert ounces to tonnes?
Multiply the number of ounces by 2.83495231e-05. To reverse it, divide by 2.83495231e-05 instead.
How do I convert tonnes back to ounces?
Divide by 2.83495231e-05, which is the same as multiplying by 35273.9619.
How many tonnes are in 10 ounces?
10 oz works out to 0.000283 t.
Is there anything to watch out for with ounces?
Not the same as a fluid ounce, which measures volume. Also distinct from the troy ounce (31.103 g) used for gold and silver.
How is the ounce defined?
Exactly 28.349523125 grams — one sixteenth of the international avoirdupois pound.