Helium Tank Size Calculator

A standard 11-inch latex balloon needs about 0.5 cubic feet of helium. A 16-inch latex needs about 1.5 cubic feet and a 36-inch round latex about 15 cubic feet (one F50 cylinder). An 18-inch foil balloon needs about 0.5 cubic feet. Round latex balloons need exponentially more helium because their volume increases with the cube of the diameter; flat foil/mylar balloons grow much more slowly than that.

For 50 standard 11-inch latex balloons, you need approximately 25 cubic feet of helium (plus 10% wastage). A large disposable tank (28 cubic feet) would be sufficient. For a mix of latex and foil, calculate each type separately.

Standard untreated 11-inch latex balloons float for about 8-12 hours (good-quality ones up to 24). Larger latex balloons float longer because they leak slower: a 16-inch holds for roughly 20-30 hours and a 24-inch upwards for 1-3 days. Foil balloons can stay inflated for 3-5 days. Treating latex with Hi-Float sealant extends float time several times over.

For fewer than 30 balloons, a small disposable tank is cheapest. For 30-60 balloons, a large disposable or small hire tank offers best value. Over 60 balloons, hiring a large refillable tank is most economical. Factor in the deposit for hire tanks.