When using four-balloon clusters to create spirals and columns, the following chart and formulas help determine the number of balloons and clusters needed for a known length, depending on the balloon size used.
| Balloon Size (latex) | Balloons per Foot |
| 5 inch* | approx 13 |
| 7 inch | approx 9 |
| 9 inch | approx 7 |
| 11 inch | approx 6 |
| 14 inch | approx 5 |
| 16 inch | approx 4 |
The way to calculate the number of clusters needed is to determine
the length of the spiral or column (n feet), multiply that figure by the number
of balloons per foot (use chart), and divide the total by four (the number of
balloons in each cluster; divide by five for five-balloon
clusters).
Example: 12 multiplied by 6 divided by 4 equals 18. Thus, a
12-foot spiral would require 18 four-balloon clusters (using 11-inch
balloons).
There will be slight variations when using a combination of
latex and foil ballons in a four-ballon cluster.
If the spiral is to be
used as an arch or swag, use the following formulas:
For an arch that is
higher than it is wide: (2 times height) plus width equals total length. For an
arch that is wider than it is high: height plus width equals total length.