The most common sign mistake we see isn't the wrong wording. It's the wrong size. A sign that's too small gets ignored, and one that's too big looks out of place on a door. This guide helps you pick the right size for where the sign will go and how far away people will read it.
Our standard sizes
| Size | Best for | Typical reading distance |
|---|---|---|
| 225mm x 300mm | Doors, cupboards, machines, above extinguishers | Up to about 5 m |
| 300mm x 450mm | Internal walls, warehouses, car park bays, pool fences | About 5–10 m |
| 450mm x 600mm | Site fences and gates, yards, loading docks, driveways | About 10–20 m |
| 600mm x 900mm | Site entries, roads, farm gates, event parking | 20 m and more, or read from a moving vehicle |
| 400mm x 75mm and 600mm x 100mm | Statutory door signs (fire doors, services rooms) | Close up, at the door |
These distances are rough guides for good lighting and people standing or walking. Go up a size for drivers, poor light, busy backgrounds or safety-critical messages. For the slim door formats, see our 400x75 vs 600x100 guide.
A quick rule of thumb
A common rule of thumb is about 25mm of letter height for every 10 metres of viewing distance in good conditions. If people need to read the sign quickly, from a vehicle, or in an emergency, allow more. Fewer words means bigger letters on the same sign, so keep messages short.
Size by situation
- Construction site fences: 450mm x 600mm or bigger, so they're readable from the street. See our construction site signs guide.
- Car parks: 300mm x 450mm for bays, 450mm x 600mm at entries. See our car park checklist.
- Warehouses and loading docks: go big for drivers. See our loading dock guide.
- Fire equipment and doors: 225mm x 300mm or the slim formats. See our fire extinguisher signs guide.
- Farm gates and rural roads: 600mm x 900mm. See our farm gate signs guide.
Material matters too
A big sign needs a stiff material: aluminium or ACP for anything 450mm x 600mm and up that stays outdoors. Corflute suits temporary signs, and vinyl stickers suit smooth surfaces. See our material guide, reflective guide and finishing options guide.
Frequently asked questions
Can I get a size that isn't listed?
Our custom signs are the best place to start for unusual sizes or layouts.
Is it cheaper to buy a few big signs or many small ones?
It depends on the job, but bulk savings apply to 25 or more of the same sign (5% off), 50+ (10%) and 150+ (15%), and shipping is free on orders over $500.
Looking for something else? Browse every guide in our Sign Guide Library.
