Balloon Helium Calculator
Calculate how many helium balloons you can fill from a tank, or how much helium you need to fill a certain number of balloons by size.
Balloons per Tank
Helium balloons float because helium is lighter than air. The volume of helium needed depends entirely on the size of the balloon being inflated.
Volume of helium per balloon by size:
| Balloon Size | Volume Needed | Float Time |
|---|---|---|
| 5 inch | 0.05 cubic feet (1.4 L) | 4–6 hours |
| 9 inch | 0.25 cubic feet (7 L) | 12–18 hours |
| 11 inch (standard) | 0.5 cubic feet (14 L) | 18–24 hours |
| 12 inch | 0.65 cubic feet (18 L) | 24–36 hours |
| 14 inch | 1.1 cubic feet (31 L) | 1–2 days |
| 16 inch | 1.6 cubic feet (45 L) | 2–3 days |
| 18 inch | 2.2 cubic feet (62 L) | 2–3 days |
| 24 inch | 5.0 cubic feet (142 L) | 3–4 days |
| 36 inch | 16.0 cubic feet (453 L) | 1–2 days (heavier) |
Common helium tank sizes:
| Tank Size | Cubic Feet | Liters | Common Name |
|---|---|---|---|
| Small party tank | 8.9 cu ft | 252 L | Party City disposable |
| Medium tank | 14.9 cu ft | 422 L | Small rental tank |
| Large tank | 55 cu ft | 1,557 L | Standard rental |
| Extra large | 110 cu ft | 3,115 L | Large event tank |
Tips for longer float times:
- Use Hi-Float (a rubberizing solution inside the balloon) — extends float time by 25× for latex balloons
- Avoid inflating in extreme heat or cold — balloons expand in heat and shrink in cold
- Mylar / foil balloons float 3–10× longer than latex at the same size
- Tie balloons securely — a loose knot leaks helium quickly
- Do not overinflate — the balloon should feel firm but not taut (overinflated balloons pop and float shorter)
Note about outdoor vs indoor:
Outdoor balloons in summer heat may expand and pop before the event. Inflate 10–15% under full capacity for outdoor summer events.