US Flag Size and Proportions Calculator
Enter any one flag measurement and this calculator returns all official US flag element dimensions using the proportions set by Executive Order 10834. You can also enter your flagpole height to get the recommended flag size. Switch between feet, inches, centimetres, and metres. All calculations update instantly.
Official US flag proportions
The dimensions of the United States flag are governed by Executive Order 10834, signed by President Eisenhower on August 21, 1959, after the 50th star was added for Hawaii. The order sets precise proportions for every element, all derived from a single base measurement called the hoist (the height of the flag, or the short side). The hoist-to-fly ratio is 1 to 1.9, meaning a 3-foot-tall flag must be 5.7 feet long. The 13 stripes are each 1/13 of the hoist, the blue canton (union) is 7/13 of the hoist tall and 2/5 of the fly wide, and the 50 stars are arranged in a specific 5-by-4 and 4-by-5 alternating row pattern within that canton.
How to use this calculator
Choose "Flag dimensions" mode and enter either the hoist (height) or the fly (length) of your flag in any unit. All 8 official element dimensions will be calculated instantly from that single measurement. Or switch to "Flag size from pole height" mode, enter your pole height and select your display type (outdoor general, outdoor large, or indoor), and the tool returns the recommended flag fly and hoist, plus the nearest commercially available standard size. All outputs update as you type, and you can switch between feet, inches, centimetres, and metres.
Choosing the right flag size for your pole
Industry standards recommend the flag fly be 1/4 to 1/3 of the total pole height for outdoor displays. Shorter ratios (1/4) suit areas with frequent high winds, as a smaller flag reduces load on the hardware. Longer ratios (1/3) give maximum visual impact for ceremonial settings. For indoor displays the flag fly is typically 1/5 of the pole height. The most common residential combination is a 3 ft x 5 ft flag on a 20-25 ft pole. Commercial or government buildings typically use 5 ft x 8 ft or 6 ft x 10 ft flags on 30-40 ft poles.
Flag colors and the canton
Official US flag specifications also include the colors: Old Glory Red (#B22234), Old Glory Blue (#3C3B6E), and White (#FFFFFF). The blue canton occupies the upper-left corner, covering the top 7 stripes in height and roughly 40 percent of the fly in width. The 50 stars are arranged in 9 alternating rows: 5 rows of 6 stars and 4 rows of 5 stars, for a total of 50. Stars point upward and are spaced evenly by the E (vertical) and F (horizontal) gaps specified in the executive order.
Official US flag element proportions (Executive Order 10834)
| Symbol | Element | Proportion (of hoist) | Fraction |
|---|---|---|---|
| A | Hoist (height) | 1.0000 | 1 |
| B | Fly (length) | 1.9000 | 19/10 |
| C | Union hoist | 0.5385 | 7/13 |
| D | Union fly | 0.7600 | 2/5 of fly |
| H | Stripe width | 0.0769 | 1/13 |
| G | Star diameter | 0.0616 | 4/5 of H |
| E | Star vertical gap | 0.0538 | 1/10 of C |
| F | Star horizontal gap | 0.0633 | 1/12 of D |
All proportions are ratios relative to the hoist (A = 1.0). These exact fractions are required for official government flags.
Frequently asked questions
What is the official aspect ratio of the US flag?
The official hoist-to-fly ratio is 1 to 1.9, often written as 10:19. This is set by Executive Order 10834 (1959). A flag that is 3 feet tall must be 5.7 feet long to be officially proportioned. Many commercial flags approximate this with 3 x 5 ft (ratio 1:1.667) or 4 x 6 ft (ratio 1:1.5), which are close enough for residential use but are not the exact government specification.
How many stripes are on the US flag, and how wide are they?
The US flag has 13 stripes (7 red and 6 white), one for each of the original colonies. Each stripe is 1/13 of the hoist (height). For a standard 3 ft x 5 ft flag, each stripe is about 2.77 inches wide. The top and bottom stripes are both red.
What size flag do I need for a 20-foot pole?
For a 20-foot outdoor pole with the general outdoor formula (pole / 4), you need a flag about 5 feet long (fly) and 2.63 feet tall (hoist). The nearest standard commercial size is a 3 ft x 5 ft flag, which is the most common residential size and works well on 20-25 ft poles.
What does hoist mean on a flag?
Hoist is the vertical dimension of the flag, the height or the short side when the flag is displayed horizontally. The hoist is also the edge closest to the flagpole. The opposite horizontal dimension is called the fly. For the US flag, the fly is always 1.9 times the hoist.
What is the blue field on the US flag called?
The blue field in the upper-left corner is called the canton or union. It contains all 50 stars and covers 7/13 of the hoist in height and 2/5 of the fly in width. The canton is always displayed in the upper-left when the flag is viewed from the front.
Are commercial flag sizes officially proportioned?
Most commercially available flags use simplified proportions that differ slightly from the official 10:19 ratio. A 3 ft x 5 ft flag has a ratio of 1:1.667, and a 4 ft x 6 ft flag has a ratio of 1:1.5, both shorter than the official 1:1.9. Flags used by the federal government and military must follow Executive Order 10834 exactly.