Balloon Calculator
Calculate balloons needed for arches and ceiling fills, with helium tank estimates.
Typical Arch Lengths
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
Can't find what you need?
Request a ToolHow to Use the Balloon Calculator
Whether you are building a balloon arch or filling a ceiling, this calculator tells you exactly how many balloons and how much helium you need. Here is how to use it:
- Choose your arrangement type. Select Balloon Arch for an entrance arch or photo backdrop. Select Ceiling Fill for floating balloons covering a room ceiling.
- Enter the measurement. For an arch, enter the total arc length in feet. A standard doorway arch is about 8 feet; a large freestanding arch is 15-20 feet. For ceiling fill, enter the room area in square feet.
- Choose balloon size (arch only). Standard 11-inch balloons use 4 per foot of arch and 0.5 cubic feet of helium each. Smaller 6-inch balloons use 6 per foot and 0.25 cubic feet each. Mixing sizes is popular for an organic arch look — use the 11-inch calculation and add about 20% for accent balloons.
- Read the helium estimate. The calculator shows cubic feet of helium needed and whether you need a small tank (14.9 cu ft, about 30 balloons) or large tank (55 cu ft, about 100 balloons).
About the Balloon Calculator
Balloon arch density standards come from professional balloon decorators. The 4-per-foot rule for 11-inch balloons creates a full, lush arch with minimal gaps. The 6-per-foot rule for 6-inch balloons compensates for the smaller diameter. Helium consumption is based on 0.5 cubic feet per 11-inch balloon and 0.25 cubic feet per 6-inch balloon, which are the standard inflation volumes for these sizes.
Ceiling balloon fill uses 1 balloon per 2.5 square feet as the midpoint of the 2-3 sq ft range. Tighter packing (1 per 2 sq ft) creates a dramatic full ceiling. Looser packing (1 per 3 sq ft) gives a lighter, airier look with visible gaps. Balloons must be inflated with helium for ceiling floats, and most balloon decorators add a hi-float solution inside each balloon to extend float time to 2-5 days.
Frequently Asked Questions
How many balloons do I need for a balloon arch?
For an 11-inch balloon arch, use 4 balloons per foot of arch length. A 12-foot arch needs 48 balloons. A 20-foot arch needs 80 balloons. For 6-inch balloons, use 6 per foot. Many professional arches mix sizes — use the 11-inch count as your base and add 20-30% extra for smaller accent balloons.
How much helium do I need for 100 balloons?
For 100 standard 11-inch balloons, you need about 50 cubic feet of helium. A large tank holds 55 cubic feet and fills approximately 100 balloons, making it the right size. A small tank holds 14.9 cubic feet and fills about 30 balloons — you would need 4 small tanks to fill 100 balloons, which costs significantly more than one large tank.
How long do helium balloons last?
Standard latex balloons inflated with helium float for 8-12 hours without treatment. Adding Hi-Float (a sealant solution) extends float time to 2-5 days for 11-inch latex balloons. Foil (Mylar) balloons float for 3-5 days without any treatment. For events longer than a day, use foil balloons or treat latex with Hi-Float. Avoid inflating balloons more than a few hours before your event if not using Hi-Float.
Can I build a balloon arch without helium?
Yes. Air-filled balloon arches on a frame or PVC pipe structure are increasingly popular and do not require helium. Air-filled balloons last much longer (days to weeks) and are lighter, making them easier to transport and set up. The same balloon counts apply whether using helium or air — only the helium estimate becomes irrelevant. Air-filled arches also work indoors and outdoors without the risk of balloons floating away.