A flag should be large enough to read clearly without overwhelming its pole or surrounding property. Pole height is the starting point, but exposure, clearance and hardware also matter.
Start with pole height
Canadian Heritage pairs a 3 × 6 ft flag with a 17–20 ft exterior pole, a 4.5 × 9 ft flag with a 30–35 ft pole, and progressively larger flags with taller poles. These dimensions are a useful planning reference.
Check the real surroundings
Nearby trees, buildings, lighting, overhead obstructions and the distance from the viewer can change what looks balanced. Confirm that the flag can fly freely without contacting another surface.
Match hardware and exposure
Larger flags create greater loads in wind. The flag, halyard, fittings, pole and foundation should be considered as one system rather than selected independently.
Reference: Canadian Heritage flying rules
Quick answers
Frequently asked questions
Is a 3 × 6 ft flag suitable for a 20 ft pole?
It is within the Canadian Heritage reference range for a 17–20 ft exterior permanent pole, subject to the actual pole and site.
Should an indoor flag use the same sizing rule?
Not necessarily. Indoor displays are shaped more by ceiling clearance, stand proportions, sightlines and presentation format.