Flag Proportion & Ratio Calculator
Give a hoist:fly ratio and one known dimension, and get the other dimension plus the total area — the arithmetic behind every flag-making spec sheet.
Resolved dimensions
How the ratio works
A flag’s hoist:fly ratio is a simple proportion: if the ratio is a:b, then fly = hoist × (b / a), or equivalently hoist = fly × (a / b). Multiplying the two gives the area. Because it’s a pure ratio, the same math scales a lapel-pin flag and a parade-ground flag identically — only the units change.
Square flags (1:1) are the exception rather than the rule; most national and organisational flags fall between 2:3 and 3:5, with a smaller number running longer and narrower near 1:2. Picking the right ratio first is the only step that matters — the rest is multiplication.
Frequently Asked Questions
What do "hoist" and "fly" mean?
The hoist is the edge of a flag that runs along the pole — its vertical dimension when the flag is flown. The fly is the length that streams out in the wind — its horizontal dimension. Vexillologists describe a flag's shape as a hoist:fly ratio, such as 2:3 or 1:2.
Why do ratios vary so much between flags?
There is no single worldwide standard. Some flags are close to square (near 1:1), most fall between 2:3 and 3:5, and a few run long and narrow at 1:2. The ratio is simply a design choice fixed by whoever specified the flag, and it stays constant no matter how large or small the flag is made.
How do I use this calculator?
Pick a ratio, then enter the dimension you already know — the hoist or the fly — in any unit (feet, meters, inches; just be consistent). The calculator scales the other dimension to match the ratio and reports the resulting area in the same square units.
Does the ratio change if I resize the flag?
No — a ratio describes shape, not size. A 2:3 flag scaled up to fly from a stadium or down to fit a desk stand keeps the same 2:3 proportion between hoist and fly; only the absolute dimensions change.
Educational tool only. Results are exact ratio arithmetic rounded for display; when a project depends on an exact size, confirm the specification with your flag maker.