For a full, organic balloon arch built from a mix of 5-, 11- and 17-inch balloons, plan on about 10 balloons for every foot of garland, so a 10-foot garland takes about 100 balloons and a 20-foot garland about 200. Measure along the curve of the arch, not across the bottom, and buy about 10 percent extra for the few that pop.
That one rule covers most arches, but the count still moves with the shape of your arch, the balloon sizes you use and how full you want it to look. Below we show you how to measure, give you counts for the common sizes, and explain how to split the balloons by size. If you would rather skip the math, our DIY balloon arch kits come counted out for the length you need.
How do you measure a balloon arch?
Every count starts with the length of the garland, and that is longer than the arch is wide. The garland has to climb up one side, cross the top and come back down, so measuring the span across the bottom is the most common way people come up short.
There is a simple shortcut. A burton + BURTON balloon arch tutorial estimates the garland length from the arch's height and width, and Omni Calculator's balloon arch calculator uses the same rule with a middle case added for arches that are about square:
Taller than it is wide (a doorway or entrance): two times the height, plus the width.
About as tall as it is wide: one and a half times the height, plus the width.
Wider than it is tall (over a long table or a stage): the height plus the width.
So an arch around a doorway that is 7 feet tall and 4 feet wide needs about 18 feet of garland, not 4. If you are covering a frame you already own, skip the formula and run a tape measure or a piece of string along the frame itself.
How many balloons per foot of arch?
It depends on the style of arch. The three you will see most often take very different numbers of balloons.
Organic arch (mixed sizes)
This is the loose, full, cloud-like look you see at most parties now, built from three sizes of balloons clustered on a flexible core. We plan on about 10 balloons per foot for this style. That lines up with HICO Memphis's balloon count guide, which puts a 10-foot organic arch at 80 to 100 balloons using 11-inch balloons alone; mixing in small and large sizes fills the gaps and brings the count up.
Classic arch (clusters of four)
A classic arch uses same-size balloons tied in groups of four and wrapped around a line or frame for a neat, uniform pattern. burton + BURTON's method: turn the garland length into inches, divide by the inflated size of your balloons to get the number of four-balloon clusters, then multiply by four. Their example arch, at 30 feet of garland with balloons inflated to 10 inches, takes 144 balloons, or a little under 5 per foot.
Single-row arch (string of pearls)
One balloon after another on a single line. Omni Calculator puts this at about one 11-inch balloon per foot, which makes it the lightest style and the one that uses the fewest balloons, but also the least full.
Balloon count by arch size
Here is how the 10-per-foot rule works out for an organic arch, with about 10 percent added for pops.
6 feet of garland: about 60 balloons, or 66 with extras.
10 feet of garland: about 100 balloons, or 110 with extras.
12 feet of garland: about 120 balloons, or 132 with extras.
16 feet of garland: about 160 balloons, or 176 with extras.
20 feet of garland: about 200 balloons, or 220 with extras.
And here is what that means for a few arches people build all the time, using the measuring shortcut above:
Dessert or cake table arch, 5 feet tall and 6 feet wide: about 11 feet of garland, so about 110 balloons.
Doorway arch, 7 feet tall and 4 feet wide: about 18 feet of garland, so about 180 balloons.
Photo backdrop arch, 8 feet tall and 8 feet wide: about 20 feet of garland, so about 200 balloons.
Treat these as planning numbers. A garland draped across the top of a backdrop, or a half arch that climbs one side, needs only the length it actually covers; HICO notes that a half arch takes roughly half the balloons of a full one.
What size balloons should you use for a balloon arch?
Three sizes. Mixing sizes is what gives an organic arch its depth, and arches built from one or two sizes tend to look like a row of balloons no matter how carefully they are put together. On our own garlands we split the count about like this:
11-inch balloons, about 48 percent. These build the body of the garland.
5-inch balloons, about 40 percent. These tuck into the gaps so you don't see the core.
17-inch balloons, about 12 percent. These are the statement balloons that break up the line.
For a 10-foot garland, that comes to about 48 eleven-inch, 40 five-inch and 12 seventeen-inch balloons. The garland is built on a core of long, skinny 260 balloons, which act as a flexible spine, so you don't need a plastic strip.
Do you need helium for a balloon arch?
No. Arches and garlands are built with air. You want the balloons to hold their shape against a wall or a frame, not pull upward, and air-filled balloons last much longer than helium ones. Our guide to how long latex balloons last inflated covers how long an air-filled arch holds up indoors and outside.
How many extra balloons should you buy?
Add 10 percent to your count. A few balloons always pop while you are inflating and tying, and a few more come out the wrong size. HICO suggests 10 to 15 percent for breakage and inflation variation, and we pack 10 percent extra into every kit for the same reason. Having spares of every size and color also means you can patch a gap on the day of the event without a trip to the store.
What changes how many balloons you need?
How full you want it. A light, airy arch can run a little under 10 per foot; a dense, lush one can run well over.
How big you inflate. Balloons inflated smaller than their full size cover less ground, so you need more of them. Pick a size for each balloon and keep it consistent.
Frame or no frame. A free-standing frame or a backdrop stand gives you a fixed length to cover. A garland hung on a wall can stop wherever you like.
Accents. Large statement balloons, greenery or flowers worked into the garland take up space that balloons would otherwise fill.
The miss we see again and again isn't the count per foot, though. It's the length. Someone measures the doorway they want to frame, orders a garland that long, and finds it stops around shoulder height on both sides. Measure the curve first and everything after that falls into place.
Want the count done for you?
If you are building it yourself, our DIY balloon arch and garland kits come in four lengths from 6 to 20 feet, with professional latex in all three sizes, the core and 10 percent spares already counted and bagged by color, and they ship anywhere in the U.S. If you are in Minnesota, western Wisconsin or Southwest Florida and would rather have it built and installed for you, see our balloon garlands, towers and arches, then send us your date and colors for a quote.