How this calculator works
The flag is described by a small set of ratios rather than a single fixed size, so any hoist can be scaled exactly. The fly is 1.9 times the hoist. The field of thirteen stripes is divided equally, which makes each stripe one thirteenth of the hoist. The union occupies the top seven stripes, so its height is seven thirteenths of the hoist, and it extends 0.76 of the fly. The fifty stars are arranged in nine rows alternating six and five stars; this page places them on a uniform grid of twelve columns by ten rows, which is the usual practical layout. The star diameter is 0.0616 of the hoist, the official figure for the current fifty-star flag.
Formula
fly = 1.9 x hoist. stripe width = hoist / 13. union height = 7/13 x hoist. union length = 0.76 x fly. star diameter = 0.0616 x hoist. The horizontal star pitch is the union length divided by 12 and the vertical pitch is the union height divided by 10.
Worked example
A flag with a hoist of 1.3 metres has a fly of 2.47 metres, and each stripe is 10 centimetres wide. The union is 70 centimetres high and 1.8772 metres long. Each star is 8.008 centimetres across, with star centres 15.643 centimetres apart across the union and 7 centimetres apart between rows.
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Frequently asked questions
Are these proportions mandatory?
Executive Order 10834 specifies the proportions and sizes for flags of the United States, and Title 4 of the United States Code gives the design. Flags made for display generally follow the official proportions, but the order also lists standard sizes for different uses, and ceremonial or historical flags may differ.
Why is the fly longer than the hoist?
The flag is designed to fly from a pole, so the long dimension streams downwind. The 1.9 to 1 ratio gives the familiar shape and keeps the canton, which is nearly square in print terms, readable when the flag is hanging limp or flying.
How many stars and stripes are there?
Fifty stars, one for each state, and thirteen stripes for the original thirteen colonies. The stars have been arranged in several patterns over history; the current nine-row alternating pattern arrived with the admission of Alaska and Hawaii in 1959 and 1960.
Can I use this to size a flag for a pole?
Yes. Flag suppliers usually recommend a flag length of about one quarter to one third of the pole height, with the hoist attached to the pole. Use this page to keep the official shape once you have chosen the pole and flag size.