Fire Pit Clearance Calculator
Safe fire pit circle, overhead, and pad size from pit diameter.
What it does
A fire pit throws heat farther than flames reach. Chairs, fences, and low branches can scorch well outside the bowl, so a clear circle matters more than pit walls.
The tool above turns pit diameter into three guards. A 36 in wood pit needs 16 ft clear in all directions, 21 ft open above, and a 7 ft noncombustible pad. The metric match is 91 cm toward 4.9 m, 6.4 m, and 2.1 m.
Ground clearance scales with size. Each foot of pit adds 2 ft of circle, starting from a 10 ft base, while gas trims 2 ft for its calmer ember bed. Overhead adds 5 ft more for heat rise and stray sparks.
The pad breaks the fuel path. Stone, pavers, or gravel 4 ft wider than the pit stop grass ignition at the edge and give chairs a stable ring.
Rules still rule. Burn bans, lot lines, and HOA terms can forbid fires that pass the math, and wind over a dry yard should delay any burn.
How to use
- Pick imperial (in, ft) or metric (cm, m).
- Enter pit diameter.
- Pick wood or gas.
- Read ground clearance first.
- Read overhead next.
- Build the pad, then measure the circle.
Formula
- pit
- Pit diameter across the bowl.
- fuel
- Wood or gas fuel.
Pit feet equal diameter inches over 12, or cm over 30.48. Metric shows meters at 0.3048 per foot.
Worked example
Example: 36 in wood pit
Imperial defaults: 36 in wood pit. These are also the default values, so the page opens on this answer.
- Pit: 36 in wood burner.
- Feet: 36 / 12 = 3 ft.
- Clearance: 10 + 3 x 2 = 16 ft in all directions.
- Overhead: 16 + 5 = 21 ft open above.
- Base: 3 + 4 = 7 ft diameter pad.
- Tool shows 16 ft clearance, 21 ft overhead, 7 ft diameter pad.
Reference table
| Pit | Clearance | Overhead |
|---|---|---|
| 24 in | 14 ft | 19 ft |
| 30 in | 15 ft | 20 ft |
| 36 in | 16 ft | 21 ft |
| 48 in | 18 ft | 23 ft |
Limits
- Planning guide only, not code approval.
- Ignores wind, slope, and dry fuel loads.
- Local bans and HOA terms override math.
- Ember screens and lids still needed.
Common mistakes
- Measuring from flames, not the bowl edge.
- Forgetting branches above the pad.
- Placing on wood deck with no rated barrier.
- Burning on windy dry days.
- Leaving ash with live coals overnight.
Try it yourself
Quick checks. Answers sit tucked under each question.
24 in wood pit?
Pit is 24 / 12 = 2 ft. Clearance is 10 + 4 = 14 ft. Overhead is 14 + 5 = 19 ft. Base is 2 + 4 = 6 ft.
36 in gas pit?
Pit is 36 / 12 = 3 ft. Gas clearance is 10 + 6 - 2 = 14 ft. Overhead is 19 ft.
Questions
How much ground clearance?
Add twice the pit feet to 10. A 3 ft pit needs 10 + 6 = 16 ft clear in all directions.
How much overhead?
Add 5 ft to ground clearance. Here 16 + 5 = 21 ft with no branches or wires above.
How big a base pad?
Add 4 ft to pit feet. A 3 ft pit needs a 7 ft noncombustible pad.
Gas versus wood?
Gas earns 2 ft less ground clearance in this plan, never below 10 ft. Wood keeps the full band.
Do local rules override?
Yes. Local rules, burn bans, and HOA limits override any math here. Check before lighting.
Is clearance enough alone?
No. Wind, slope, and dry grass raise risk past the base numbers.