This converter turns ounces into tonnes instantly, using the exact factor 1 ounce = 2.834952313e-05 tonnes. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
The avoirdupois ounce, exactly 28.349523125 grams — standard in US recipes. The metric ton: exactly 1,000 kilograms, used for freight and vehicle mass.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
ounces- The amount you are converting, measured in ounces
2.834952313e-05- The exact number of tonnes in one ounce
tonnes- The converted result
How it works, step by step
- Enter the number of ounces you want to convert.
- The value is multiplied by 2.834952313e-05, the exact conversion factor.
- The result is displayed in tonnes, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 ounces
Multiply 5 by 2.8349523e-05. That gives 0.000142 tonnes. A quick sanity check: one ounce is smaller than one tonne, so the number should get smaller — and it does.
Converting 72 ounces
72 × 2.8349523e-05 = 0.002041 tonnes. Working backwards, 0.002041 ÷ 2.8349523e-05 returns 72 ounces, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many tonnes are in one ounce?
Exactly 2.834952313e-05. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert ounces to tonnes?
Tonnes = ounces × 2.834952313e-05. To reverse it, divide instead: ounces = tonnes ÷ 2.834952313e-05, which is the same as multiplying by 35273.96195.
Is the ounce bigger than the tonne?
No. One ounce is only 2.83495e-05 of a tonne, so the tonne is the larger unit.
Why does my answer differ slightly from other ounces to tonnes converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a ounce?
The avoirdupois ounce, exactly 28.349523125 grams — standard in US recipes.
What is a tonne?
The metric ton: exactly 1,000 kilograms, used for freight and vehicle mass.
Ounces to tonnes reference table
| Ounces | Tonnes |
|---|---|
| 0.5 oz | 0.000014 t |
| 1 oz | 0.000028 t |
| 2 oz | 0.000057 t |
| 3 oz | 0.000085 t |
| 5 oz | 0.000142 t |
| 10 oz | 0.000283 t |
| 15 oz | 0.000425 t |
| 20 oz | 0.000567 t |
| 25 oz | 0.000709 t |
| 50 oz | 0.001417 t |
| 75 oz | 0.002126 t |
| 100 oz | 0.002835 t |
| 250 oz | 0.007087 t |
| 500 oz | 0.014175 t |
| 1000 oz | 0.02835 t |
Exact factor: 1 ounce = 2.834952313e-05 tonnes. Values rounded for display.