How to choose grid size and radius for a local rank scan
Too small and you miss the real picture, too big and you measure places you do not serve. A practical guide with examples.
Grid size and radius decide what your heatmap means. Get them wrong and you will either celebrate a tiny green square or panic about red pins in a suburb you never serve.
Start from the service area, not the tool
Ask one question: how far do customers travel to you, or how far do you travel to them? That distance is your radius. A coffee shop in a dense city centre might be 1 km. A plumber covering a county might be 25 km.
Pick the grid size from the radius
- 1 to 2 km radius: 5x5 or 7x7 is plenty, points are a few hundred metres apart
- 3 to 8 km radius: 7x7 or 9x9 keeps spacing sensible
- 10 km and up: 9x9 to 13x13, otherwise pins are so far apart that whole neighbourhoods fall between them
Service-area businesses
If you do not have a storefront, centre the grid on the area you want to win, not on your home address. The service-area business guide covers this in detail. You can set a custom centre on every scan.
A worked example
A dental clinic in a mid-sized city serves roughly a 4 km radius. A 7x7 grid at 4 km gives 49 points about 1.3 km apart. That is enough to see the shape of the visibility area without noise. Re-scan weekly, compare monthly.