Capacity and water weight
| Capacity | Water alone weighs about | Possible uses |
|---|---|---|
| 250–350 ml | 0.25–0.35 kg | Short outings, smaller carrying needs |
| 350–500 ml | 0.35–0.5 kg | Personal carrying where refill access exists |
| 750 ml | 0.75 kg | Desk or longer periods between refills |
| 1 L | 1 kg | Desk, table, fridge or shared use |
Add the empty bottle's own weight to estimate the actual load. Glass can add substantially more weight than some steel or plastic designs.
School use
There is no universal “school standard” size. Choose a capacity a particular child can carry and open, and consider refill access and the school's material policy. See the school guide.
Office and institutional use
The 2026 state-sector single-use bottle measure does not prescribe one reusable-bottle capacity. Institutions should choose sizes from their actual refill, desk, meeting and field-use requirements rather than treating 750 ml or 1 L as an official replacement standard.
Measure the space
1
Bag pocketCheck diameter and height, not capacity alone.
2
Fridge or shelfMeasure clearance before ordering handled or tall bottles.
3
Refill frequencyA smaller bottle can work well where refills are easy; a larger one may reduce refill frequency but adds weight.