The standard American flag dimensions should be between one-quarter and one-third the height of the flagpole. Using the one-quarter rule, you would need a 3 ft. by 5 ft. flag size for a 20 ft. flagpole. Two major factors in determining what flag dimensions you should use for your in-ground flagpole are material and wind exposure.
For material, cotton fabric is very durable, but fades fast under extreme sun exposure. A budget-friendly option is the 1-ply polyester, but if your flag is wearing out every 6 months or less, you will need to switch to a tougher material. 2-ply polyester flags are perfect for high winds or extreme outdoor conditions. Nylon flags are the most popular for their fair price, strength, and only take a light wind to lift most flag sizes.
Download our standard flag size chart in a handy pdf.
For information regarding the durability of outdoor flags, check out our article, “How Long will a Flag Last?” To determine the amount of wind your flag can be exposed to, see our Wind Speed Chart for American flag sizes only. Of course, the unique location and surroundings -- like wind tunnels, ocean breezes, and landscapes -- also influence the right choice of flags for flag poles.
What Size Flag Do I Need to Purchase for My Flagpole?
 | Flagpole Style | Height (length) of Pole | Flag Size |
| House Mounted | 5 ft. | 2-1/2 ft. x 4 ft. | |
| House Mounted | 6 ft. to 8 ft. | 3 ft. x 5 ft. | |
| In Ground | 8 ft. | 3 ft. x 5 ft. | |
| In Ground | 10 ft. | 3 ft. x 5 ft. | |
| In Ground | 15 ft. to 19 ft. | 3 ft. x 5 ft. | |
| In Ground | 20 ft. to 24 ft. | 3 ft. x 5 ft. or 4 ft. x 6 ft. | |
| In Ground | 25 ft. to 29 ft. | 5 ft. x 8 ft. or 6 ft. x 10 ft. | |
| In Ground | 30 ft. to 39 ft. | 5 ft. x 8 ft. or 6 ft. x 10 ft. | |
| In Ground | 40 ft. to 49 ft. | 6 ft. x 10 ft. or 8 ft. x 12 ft. | |
| In Ground | 50 ft. to 59 ft. | 8 ft. x 12 ft. or 10 ft. x 15 ft. | |
| In Ground | 60 ft. to 69 ft. | 10 ft. x 15 ft. or 12 ft. x 18 ft. | |
| In Ground | 70 ft. to 79 ft. | 12 ft. x 18 ft. or 15 ft. x 25 ft. | |
| In Ground | 80 ft. to 89 ft. | 12 ft. x 18 ft. or 20 ft. x 30 ft. | |
| In Ground | 90 ft. to 99 ft. | 15 ft. x 25 ft. or 20 ft. x 30 ft. | |
| In Ground | 100 ft. to 119 ft. | 15 ft. x 25 ft. or 20 ft. x 38 ft. | |
| In Ground | 120 ft. to 149 ft. | 20 ft. x 38 ft. | |
| In Ground | 150 ft. to 200 ft. | 30 ft. x 50 ft. | |
| In Ground | 200 ft. + | 30 ft. x 60 ft. |
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