An untreated latex balloon floats for roughly 12–18 hours on helium, whatever the size — a 36" lasts a little longer than a 12" because it holds more gas for its surface, but plan on the same window. If the event runs longer than that, or the balloons are inflated the day before, treat them with a float product before filling, which stretches float to days. Air-filled balloons on a frame or strip don't have the problem at all, which is why most organic garlands are air, not helium. Here's how long each size lasts, how much helium it takes, and when treatment is worth it.
How long do helium balloons float?
Helium leaks out through the latex itself — the balloon isn't faulty, the gas is simply small enough to pass through. Three things change the rate:
- Size. Bigger balloons have more gas per square centimetre of skin, so they lose proportionally less. A 36" edges past a 12", but not by a full day untreated.
- Temperature. Heat makes latex more porous and expands the gas; a balloon that floats 16 hours in an air-conditioned room may droop in 8 on a hot verandah. Cold does the opposite — a balloon carried from a cold car into a warm room will sag for a minute, then recover.
- Treatment. A float product coats the inside of the balloon and slows the leak dramatically. It's the only way to get multi-day float from latex.
| Size | Untreated float | Treated float (typical) | Helium per balloon | Balloons per 9 m³ (E) cylinder, approx. |
|---|---|---|---|---|
| 5" (12cm) | Not recommended — too small to lift | — | — | — |
| 12" (30cm) | 12–18 hours | 2–4 days | about 0.5 cu ft (14 L) | about 600 |
| 18" (45cm) | 12–18 hours (toward the longer end) | 3–5 days | about 0.4 cu ft (11 L) when inflated to 16" | about 800 |
| 24" (60cm) | 12–18 hours (toward the longer end) | 4–7 days | about 1 cu ft (28 L) | about 300 |
| 36" (90cm) | 12–18 hours (toward the longer end) | 5–10 days | about 15 cu ft (425 L) at full size; less at 30–32" | about 20 |
Treated figures are typical of float products on the market; follow the product's own instructions. Cylinder counts assume a full standard E-size cylinder and balloons inflated to the garland sizes in the sizes guide; your gas supplier can give exact litres.
When should I treat balloons?
- Inflating the day before. Always treat.
- Weddings and events over 8 hours where balloons are seen at the end (send-off, cake cutting). Treat.
- Outdoor or warm venues. Treat, and expect a shorter life even so.
- Short parties, inflated on site. Untreated is fine and saves the cost.
- Chromes. Same rules; they float slightly less time than standard latex of the same size, so treat for anything past a few hours.
- Double-stuffed. Two skins are heavier; float time is noticeably shorter. Use singles for helium work.
How do I make a helium bouquet last longer without treatment?
- Inflate as late as you can — ideally on site.
- Fill to size, not past it. An over-inflated balloon is thinner and leaks faster.
- Use 18" rather than 12" for the balloons that matter; they hold up better.
- Keep them out of sun and away from air-conditioning vents and heaters.
- Tie with a tight knot, not a clip — clips leak.
Air or helium for an organic garland?
Air, almost always. A garland is mounted on a strip or frame, so nothing needs to float, and air-filled latex lasts days to weeks indoors. Helium only comes into it for floating pieces — a ceiling of 12s and 18s, a 36" on a weighted ribbon, bouquets on tables — and those are where the table above matters. Mixing the two in one design (an air garland with a helium 36" "escaping" from the end) is a nice effect; treat the 36".
Quick answers
How long does a 36 inch balloon float?
Roughly 12–18 hours untreated; days with a float treatment. Inflate to 30–32" for the best shape and life.
Can I helium-fill 5 inch balloons?
Not usefully — they'll lift for a short while then sink. Air-fill and attach.
Why did my balloons sink overnight in the car?
Cold shrinks the gas. They usually recover in a warm room; if not, they were under-filled.
Does Stylex sell helium or float treatment?
No — balloons only. Your local gas supplier and party wholesaler carry both.
Build the floating piece from the counts guide, and pick colours from the palettes guide.
Evra is a Sydney balloon stylist and the founder of Stylex Balloons, a wholesale latex balloon range made for organic decor.