Find out how much weight your helium balloons can lift, or how many balloons you need to float a card, a gift or a science project payload. The calculator uses real air and helium densities for your altitude and temperature, subtracts the weight of the balloons, and compares helium with hydrogen and hot air.
Last updated:
What do you want to find?
Balloons
Measured across the widest part
g
Include ribbon if you want it counted
%
Balloon-grade helium is often diluted with air; lower purity means less lift
Payload & conditions
What the balloons must carry (optional in lift mode)
Typical hot air balloon envelope: 200–250 °F (95–120 °C)
Enter your values to see the result.
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How to use the Helium Balloon Lift Calculator
Choose what to find: the number of balloons for a weight, or the lift of balloons you already have.
Pick the balloon size or choose Custom and enter the inflated diameter and empty weight.
Enter the payload and its unit, plus how many balloons you have in lift mode.
Set altitude and temperature where you inflate; lift drops at high-altitude locations.
Read the result, then check the gas and size tables to compare options.
Helium balloon lift formula
A balloon floats because it pushes aside air that weighs more than the gas inside it (Archimedes' principle). The calculator works it out in four steps:
Air pressure at your altitude: P = 101,325 Pa × (1 − 2.25577×10⁻⁵ × h)5.25588, with h in meters (International Standard Atmosphere).
Gas densities (ideal gas law): ρ = P × M / (R × T), with molar masses 28.96 g/mol for air, 4.003 g/mol for helium and 2.016 g/mol for hydrogen, R = 8.3145 J/(mol·K) and T in kelvin.
Lift per liter: ρair − ρgas. At sea level and 20 °C that is 1.204 − 0.166 = about 1.04 g/L for pure helium.
Net lift per balloon: volume × lift per liter − weight of the empty balloon. A sphere's volume is π/6 × d³.
Worked example: a 12-inch latex balloon (about 14.8 L, 3.3 g) at sea level, 20 °C: 14.8 × 1.04 = 15.4 g gross, 15.4 − 3.3 = 12.1 g net. To float a 100 g payload you need ⌈100 / 12.1⌉ = 9 balloons, and about 10 for a steady rise.
Lift of common gases (sea level, 20 °C)
Gas
Density (g/L)
Lift (g/L)
Lift per ft³
Notes
Air
1.204
0
0
Reference
Hydrogen
0.084
1.12
31.7 g (1.12 oz)
Most lift, but flammable
Helium, pure
0.166
1.04
29.4 g (1.04 oz)
Safe, non-flammable
Helium, 80% mixed with air
0.374
0.83
23.5 g (0.83 oz)
Similar to some diluted tank gas
Hot air, 100 °C
0.946
0.26
7.3 g (0.26 oz)
Needs a very large envelope
A handy rule: one cubic foot of helium lifts about one ounce (28 g) at sea level, and one liter lifts about one gram.
Tips for balloon projects
Add spare lift. The "balloons needed" number only balances the weight. Add 10–20% more for the bundle to rise steadily and to make up for leakage.
Weigh everything. Ribbon, tape and a small card add up quickly. A kitchen scale that reads in grams makes the estimate much better.
Bigger is more efficient. Doubling the diameter gives eight times the volume but only about four times the balloon weight, so large balloons have much more lift to spare.
Keep it indoors or tethered. Released balloons end up as litter and can harm wildlife, and helium is a limited resource, so tether your balloons and deflate them after use.
Frequently asked questions
How much weight can one helium balloon lift?
Pure helium lifts about 1.0–1.1 grams per liter at sea level. A standard 11-inch latex balloon holds roughly 11 liters, so its gross lift is about 12 grams; after subtracting the balloon itself (about 3 g) it can carry around 9 grams, roughly a third of an ounce. Bigger balloons lift far more because volume grows with the cube of the diameter.
How many helium balloons does it take to lift 1 pound?
One pound is 453.6 grams. With 11-inch latex balloons lifting about 9 grams each at sea level you would need around 50 balloons just to balance it, and more for it to rise. A few 36-inch balloons, which lift roughly 400 grams each before their own weight, do the same job with far fewer balloons.
How is helium lift calculated?
By Archimedes' principle the lift equals the weight of air displaced minus the weight of the gas inside. The calculator finds air and helium densities from the ideal gas law, ρ = P × M / (R × T), using standard-atmosphere pressure for your altitude. Lift per liter is ρ_air − ρ_helium, multiplied by the balloon volume, minus the balloon's own weight.
Do balloons lift less at high altitude?
A balloon inflated at a high-altitude location lifts less because the air there is thinner: each liter of helium displaces less air mass. In Denver (about 5,300 ft) a balloon of the same size has roughly 18% less gross lift than at sea level. Once a sealed balloon is filled, rising higher mostly makes it expand rather than lose lift, until it bursts.
Does hydrogen lift more than helium?
Yes, but only slightly. Hydrogen lifts about 1.1 grams per liter versus about 1.05 for helium at sea level, roughly 8% more, because both gases are already far lighter than air. Hydrogen is highly flammable, which is why party balloons use helium.
Why don't my balloons lift as much as the calculator says?
Common reasons are balloons that are under-inflated, diluted helium from disposable tanks, extra weight from ribbons and weights, cold air, and helium leaking through latex over a few hours. Use the purity setting and a realistic empty weight, and plan 10–20% extra balloons.
How much lift does hot air give compared with helium?
Hot air at about 100 °C (212 °F) on a 20 °C (68 °F) day lifts only about 0.26 grams per liter, around a quarter of helium. That is why hot air balloons need huge envelopes and a burner to keep the air hot.
Are all the tools on FreeToolCabin tested for quality and accuracy?
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