calcs.homes
calcs.homes
Enter your flagpole's height and we'll suggest a well-proportioned flag size — too small looks lost, too large overwhelms the pole.
Estimate only — local etiquette and HOA rules may set their own size limits.
We divide the flagpole's height by 4 to get the flag's fly (length), then divide that by 1.9 to get the hoist (height) — the US flag's standard 1:1.9 hoist-to-fly ratio. In US units, that raw size is then matched to the nearest common retail flag size from a standard list running from 3x5 up to 20x30.
The quarter-height rule keeps a flag visually balanced on its pole — too small and it looks lost at the top, too large and it can overwhelm the pole and put extra strain on the halyard and grommets in wind. Rounding to a standard retail size matters because flags aren't manufactured in custom dimensions; sellers only stock a fixed set of sizes.
A 3x5 ft flag is the standard choice for a 20 ft residential pole, following the quarter-height rule of thumb.
The official US flag ratio is 1:1.9 (hoist to fly) — a 3 ft hoist pairs with a 5.7 ft fly, which retail sizing rounds to a clean 3x5.