Flag size calculator: the right flag for your flagpole
Published Written by Flagpole Guides
Which size of flag suits a flagpole? The calculator below gives an answer based on the guide in the Flag Institute’s UK flag protocol: on a ground-level flagpole, the flag’s length is no more than one third of the pole’s height. There is no official formula in the UK; the Flag Institute calls the choice a matter of aesthetics.
How to read the results
- Maximum flag length: one third of the pole’s height above ground, shown in centimetres and in feet and inches.
- At 3:5: the normal proportions of the Union Flag for use on land, according to the Flag Institute’s specification. The flag’s height is three fifths of its length.
- At 1:2: the customary proportions of ensigns for use at sea. The flag’s height is half its length.
Examples
| Pole height | Maximum length | At 3:5 | At 1:2 |
|---|---|---|---|
| 4.6 m (15 ft 1 in) | 153 cm (5 ft) | 92 × 153 cm | 77 × 153 cm |
| 6 m (19 ft 8 in) | 200 cm (6 ft 7 in) | 120 × 200 cm | 100 × 200 cm |
| 8 m (26 ft 3 in) | 267 cm (8 ft 9 in) | 160 × 267 cm | 133 × 267 cm |
| 10 m (32 ft 10 in) | 333 cm (10 ft 11 in) | 200 × 333 cm | 167 × 333 cm |
What the guide does not cover
- Manufacturer’s limits: many flagpoles are designed for a maximum flag size, which takes priority over any rule of thumb. More in the guide to flagpole safety.
- Roof poles: according to the Flag Institute, a flagpole on top of a building may need a larger flag.
- Exposure: coastal and exposed sites put more load on pole and flag than sheltered gardens.
- Several flags: flags flown together are the same size, according to the Flag Institute.
- Half-mast: at half-mast there is at least the height of the flag between the top of the flag and the top of the pole, so a large flag on a short pole sits lower. More in the guide to half-mast.
All sizes and planning limits are in the guide to flag sizes, and typical pole heights in the guide to flagpole heights.
Frequently asked questions
How does the flag size calculator work?
It follows the guide in the Flag Institute’s UK flag protocol: on a ground-level flagpole, the flag’s length is no more than one third of the pole’s height. It then shows the flag’s height at the two customary proportions of the Union Flag, 3:5 on land and 1:2 at sea.
Is the result an official requirement?
No. There is no official rule on flag size in the UK. The Flag Institute calls the size of flag for any flagpole a matter of aesthetics and gives the one-third rule as a guide.
Does the calculator work for a flagpole on a roof?
The guide applies to ground-level flagpoles. According to the Flag Institute, a flagpole on top of a building may need a larger flag because of the added height of the building.
Can a smaller flag be used?
Yes. The result is an upper limit. A smaller flag catches less wind and loads the pole less, and many manufacturers state a maximum flag size for their poles.
Sources
This guide is based on the following sources:
- UK flag protocol – size of flag – The Flag Institute
- Union Flag specification – The Flag Institute
Related guides
- Flag sizesWhat size flag suits a flagpole: the Flag Institute’s one-third guide, a size chart by pole height, the 3:5 and 1:2 proportions and UK planning limits.
- Flagpole heightsHow tall a flagpole can be without planning permission in the UK, which flag size suits which height, the half-mast position, and the fall zone around a pole.
- Half-mastWhat half-mast means in the UK: how far down the flag flies, how it is raised and lowered, when flags go to half-mast and when a black mourning ribbon is used.
- Flag typesThe flags flown in the UK: the Union Flag, the national flags of England, Scotland and Wales, ensigns, the Royal Standard, county and house flags and pennants.