American Flag Size & Proportions Calculator
Enter any single dimension — hoist, fly, union, stripe height, or star diameter — and get every official US flag measurement per Executive Order 10834, drawn to scale.
Calculate flag dimensions
Must be greater than zero.
Results
| Dimension | Feet | Inches | cm | m |
|---|
Standard US flag sizes
Common commercial nominal sizes. Sizes marked nominal deviate from the official 1 : 1.9 hoist-to-fly ratio. Tap “Use” to load a size into the calculator.
| Size | Hoist (ft) | Fly (ft) | Union W (ft) | Union H (ft) | Stripe (ft) | Star Ø (ft) | Ratio |
|---|
The official specification
The construction of the US flag is defined by Executive Order 10834. All parts are fixed multiples of the hoist (the flag's height):
- Fly (width) = 1.9 × hoist
- Union width = 0.76 × fly
- Union height = 7/13 × hoist
- Each stripe = 1/13 × hoist (13 stripes total, 7 red, 6 white)
- Star diameter = 0.0616 × hoist (50 stars in 9 alternating rows of 6 and 5)
This is a purely geometric reference tool. It does not cover flag etiquette, display rules, or manufacturing tolerances.
Frequently asked questions
What are the official proportions of the American flag?
Per Executive Order 10834, the official ratio of hoist (height) to fly (width) is 1 to 1.9. The union (blue canton) is 0.76 times the fly in width and 7/13 of the hoist in height, each of the 13 stripes is 1/13 of the hoist tall, and each star's diameter is 0.0616 times the hoist.
How big is the union on a 3x5 ft American flag?
On a nominal 3 by 5 ft flag, the union is 0.76 times 5 ft = 3.8 ft wide and 7/13 times 3 ft = 1.6154 ft tall.
What is the diameter of the stars on the American flag?
Each star's diameter is 0.0616 times the hoist (height) of the flag. On a 3 ft hoist flag the stars are 0.1848 ft (about 2.22 in) across.
How tall is each stripe on the American flag?
Each of the 13 stripes is exactly 1/13 of the flag's hoist. On a 3 ft hoist flag, every stripe is 3/13 = 0.2308 ft (about 2.77 in) tall.
Are commercial 3x5 ft flags exactly to official spec?
Not exactly. The official hoist-to-fly ratio is 1:1.9, so a spec-exact 3 ft hoist flag would be 5.7 ft wide. Commercial 3x5 ft flags use nominal sizes; this calculator shows a note whenever a nominal size deviates from the 1:1.9 spec ratio.
How are the 50 stars arranged?
The 50 stars sit in the union in 9 horizontal rows that alternate between 6 and 5 stars. Row centers are spaced evenly at 1/10 of the union height apart, and within each row the stars are evenly spaced across the union width.
Free tool by NRTechStudio