ml to oz: water bottle and glass sizes
Bottles are sold in millilitres in most of the world and in fluid ounces in the US. Here is how the common sizes line up.
The exact factor
- 1 US fluid ounce = 29.5735 ml
- 1 ml ≈ 0.0338 US fluid ounces
US nutrition labels round 1 fl oz to 30 ml. The UK (imperial) fluid ounce is smaller: 28.41 ml. A recipe or bottle from the UK in “oz” is not the same as a US one.
Common sizes
| Metric | US fl oz |
|---|---|
| 200 ml (a small glass) | 6.8 fl oz |
| 250 ml (a glass) | 8.5 fl oz |
| 330 ml (a can) | 11.2 fl oz |
| 500 ml (a small bottle) | 16.9 fl oz |
| 750 ml | 25.4 fl oz |
| 1 litre | 33.8 fl oz |
| 1.5 litres | 50.7 fl oz |
| 2 litres | 67.6 fl oz |
| US fl oz | Metric |
|---|---|
| 8 fl oz (a cup) | 237 ml |
| 12 fl oz | 355 ml |
| 16 fl oz | 473 ml |
| 16.9 fl oz | 500 ml |
| 20 fl oz | 591 ml |
| 24 fl oz | 710 ml |
| 32 fl oz | 946 ml |
| 64 fl oz | 1.89 litres |
Tracking by bottle instead of by number
You rarely need the conversion once your containers are set up. In Water Tracker you save the glasses and bottles you actually use — “My bottle · 750 ml” or “Office cup · 12 fl oz” — and log each one with a tap. The app stores every amount in whole millilitres and shows it in ml or US fl oz, whichever you choose. Switching units never changes your history.
Sources
- NIST. Approximate conversions from U.S. customary measures to metric.
- US Code of Federal Regulations. 21 CFR 101.9 — Nutrition labeling of food (1 fl oz = 30 mL for labeling).
General information with sources, not medical advice.