How many bricks for a fire pit?
A round fire pit is built in rings. The number of bricks in each ring is the circumference at the middle of the brick divided by the brick length plus one joint:
courses = ⌈ height ÷ (brick height + joint) ⌉
bricks = bricks per course × courses × (1 + waste %)
Example: a fire pit with a 36 in inside diameter, 15 in tall, in modular brick laid flat: π × 40 in ÷ 8 in ≈ 16 bricks per course, 6 courses, 96 bricks — order 106 with 10% waste. The outside diameter is about 43½ in.
Bricks for common fire pit sizes
| Inside diameter | Bricks per course | 6 courses (≈ 15 in) |
|---|---|---|
| 30 in | 14 | 84 |
| 36 in | 16 | 96 |
| 42 in | 19 | 114 |
| 48 in | 21 | 126 |
US modular brick laid flat, one ring thick, ⅜ in joints, before waste. A two-ring (8 in thick) wall needs about 35 bricks per course at 36 in.
Fire brick or regular brick?
Ordinary clay bricks can crack and spall when exposed to direct, repeated fire. For the inner ring that faces the flames, use fire bricks (refractory bricks, 9 × 4½ × 2½ in in the US) laid with refractory mortar, and use face brick for the outer ring. Choose "Firebrick" in the brick list and calculate each ring separately if you build a double wall. Never use concrete blocks or river rock inside a fire pit — trapped moisture can make them burst.
Fire pit building tips
- Size. 36–44 in inside diameter suits most backyards; 12–18 in tall is comfortable for sitting around.
- Base. Dig out 6 in, fill with compacted gravel and leave the center open to drain.
- Air. Leave a few gaps in the bottom course (or skip head joints) to feed air to the fire.
- Rules. Check local burn regulations and keep the pit at least 10–25 ft from buildings, fences and trees.
Frequently asked questions
How many bricks do I need for a fire pit?
About 96 modular bricks for a 36 in inside-diameter fire pit 15 in tall (16 per course, 6 courses), or 106 with 10% waste.
How many bricks are in a fire pit ring?
Divide the circumference at the center of the brick by the brick length plus a joint. For a 36 in pit in modular brick, that is about 16 bricks per ring.
Can I use regular bricks for a fire pit?
For the outer ring, yes. The inner face is best built with fire bricks and refractory mortar, because ordinary bricks can crack under repeated direct heat.
What size should a brick fire pit be?
Most are 36 to 44 inches across inside and 12 to 18 inches tall. Smaller pits keep people closer to the fire; larger ones need more wood.