Calculator Input
Visual Layout Guide
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The preview shows the official 1:1.9 flag shape, thirteen stripes, and a union covering seven stripe heights.
Example Data Table
| Hoist | Fly | Stripe Height | Union Height | Union Fly | Star Diameter |
|---|---|---|---|---|---|
| 24 in | 45.6 in | 1.846 in | 12.923 in | 18.24 in | 1.478 in |
| 36 in | 68.4 in | 2.769 in | 19.385 in | 27.36 in | 2.218 in |
| 48 in | 91.2 in | 3.692 in | 25.846 in | 36.48 in | 2.957 in |
Formula Used
Fly length: Fly = Hoist × 1.9
Stripe height: Stripe = Hoist ÷ 13
Union height: Union height = Stripe × 7
Union fly: Union fly = Hoist × 0.76
Star diameter: Star diameter = Hoist × 0.0616
Star row spacing: Row spacing = Union height ÷ 10
Star column spacing: Column spacing = Union fly ÷ 12
Cut size: Add hems to both sides. Add heading allowance to the fly direction.
The calculator uses the standard United States flag proportion of 1 unit hoist to 1.9 units fly. The union covers seven stripe heights. Six-star rows use columns 1, 3, 5, 7, 9, and 11. Five-star rows use columns 2, 4, 6, 8, and 10.
How to Use This Calculator
- Select whether your known measurement is hoist height or fly length.
- Enter the measurement value in your preferred unit.
- Choose decimal places for the result precision.
- Add a scale multiplier if you need drawing or pattern dimensions.
- Add hem and heading allowances when planning cut fabric size.
- Click the calculate button to view dimensions above the form.
- Use the CSV or PDF button to save the result.
US Flag Dimension Planning Guide
Why Proportions Matter
A United States flag looks correct when every part follows the same base ratio. The hoist is the controlling height. The fly is longer than the hoist. This gives the flag its familiar rectangular shape. When the hoist changes, every stripe, union part, and star spacing changes with it.
Using the Hoist as the Main Input
The hoist is usually the easiest value to start with. It is the vertical side of the flag. Once you enter it, the calculator multiplies it by 1.9 to find the fly. It also divides the hoist by thirteen. That gives the height of each stripe.
Union and Stripe Layout
The union is the blue field. Its height equals seven stripe heights. Its fly width equals 0.76 times the hoist. This keeps the canton balanced against the long striped field. The thirteen stripes alternate red and white. Seven stripes are red. Six stripes are white.
Stars and Spacing
The star field uses nine staggered rows. Five rows contain six stars. Four rows contain five stars. The calculator gives a practical star diameter, row spacing, and column spacing. These values help with drawing, printing, embroidery, carving, and sewing layouts.
Pattern and Fabric Use
Finished size is not always the same as cut size. Fabric flags need extra material for hems. A hoist heading may also need more width. This tool includes both allowances. It helps you estimate the real material rectangle before cutting.
Best Practice
Use consistent units throughout the form. Do not mix inches with centimeters in one calculation. Round only at the end when possible. This keeps small features accurate. For large flags, use more decimal places. For simple craft projects, fewer decimals may be enough.
FAQs
1. What is the standard US flag ratio?
The standard ratio is 1 unit of hoist to 1.9 units of fly. The calculator applies that ratio automatically from either known measurement.
2. What does hoist mean?
Hoist means the vertical height of the flag. It is the side nearest the pole, sleeve, heading, or grommet edge.
3. What does fly mean?
Fly means the horizontal length of the flag. It runs from the hoist edge to the free outside edge.
4. How many stripes are used?
The flag has thirteen stripes. Each stripe has the same height, found by dividing the hoist by thirteen.
5. How is the union height calculated?
The union height equals seven stripe heights. This places the blue field across the top seven stripes.
6. Can I calculate from the fly length?
Yes. Choose fly length as the known measurement. The calculator divides it by 1.9 to find the hoist.
7. What is hem allowance?
Hem allowance is extra material added around edges. It is useful when cutting fabric before sewing the finished flag.
8. Can I save the calculation?
Yes. After calculating, use the CSV button for spreadsheet data or the PDF button for a printable summary.