How many blocks for a 48 inch fire pit?
A 48 inch fire pit built from tapered wall blocks with a 12 inch face and 7 inch depth takes 17 blocks per course, around an outside diameter of 62 inches. Three courses is 51 blocks, or 54 blocks with spares.
How to work it out
- Outside circle 3.1416 × 62 in ÷ 12 in face = 17 blocks per course
- × 3 courses + 5% spares = 54 blocks
A 4 ft bowl suits bigger gatherings and wood-burning fires, and it is the size where the pit starts to dominate a small patio — the outside is over 5 ft across.
Adjust for your project
More options: Spares
- Per course
- 17 blocks
- Outside diameter / width
- 62 in
- Wall height (dry-stacked)
- 12 in
48 in fire pit by number of courses
| Courses (layers) | Blocks to buy | Wall height (dry-stacked) |
|---|---|---|
| 2 | 36 blocks | 8 in |
| 3 | 54 blocks | 12 in |
| 4 | 72 blocks | 16 in |
| 5 | 90 blocks | 20 in |
Bigger ring, gentler curve
At 48 in inside and 62 in outside, the outer circle is 194.8 in. With 12 in faces that is 16.2 blocks — round up to 17. The larger circle is also easier to build than a small one, because tapered blocks don’t have to close up as tightly; on the biggest rings, some blocks can even be straight units with slightly open joints at the back.
Compared with a 36 in pit, the 48 in version needs about 30% more blocks per course but holds almost 80% more fire bowl area (48² vs 36²). Plan the patio around a 62 in footprint plus seating space.
Base and liner
A ring this size weighs a lot by the time it is three courses high. Set the first course on 4 in or so of compacted gravel, levelled carefully, so the ring doesn’t sink unevenly; the gravel base calculator works out tons for a pad. A steel fire ring in the matching size keeps heat off the blocks. For a smaller pit see how many blocks for a 36 inch fire pit.
Different size? Use the full Fire Pit Block Calculator.
What you’ll need
- Steel fire pit ringMid-range price
A heavy steel liner set inside a block fire pit keeps direct flame off the wall units.
See options on Amazon (opens in a new tab) - Hand tamperBudget price
Compacts gravel base in small areas and post holes. For a full slab base, rent a plate compactor.
See options on Amazon (opens in a new tab) - 4 ft levelMid-range price
Checks forms for level and slope, and plumbs block, brick and posts. A 4 ft level bridges small bumps that fool a short one.
See options on Amazon (opens in a new tab)
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Frequently asked questions
How many bricks for a 48 inch fire pit?
About 20 bricks per course, 105 bricks for five courses with spares.
How many blocks for a 48 inch fire pit, 4 courses?
72 blocks with spares (17 blocks per course).
Other common sizes
- How many blocks for a 36 inch fire pit — 13 blocks per course; 41 blocks for 3 courses with spares
- How many cinder blocks for a fire pit — 12 blocks per course (3 per side); 24 blocks for 2 courses
Sources
- Allan Block — How-to sheet #360, fire pit (opens in a new tab) — 28 AB York blocks per course make a ring about 81 in across.
- CMHA (formerly NCMA) CMU-TEC-001-23 — Concrete masonry unit shapes, sizes, properties and specifications (opens in a new tab) — Specified dimensions are 3/8 in less than nominal, so an 8×8×16 block is 7-5/8 × 7-5/8 × 15-5/8 in; nominal thicknesses 4–16 in; ±1/8 in tolerance.
- Brick Industry Association — Technical Note 10, Dimensioning and Estimating Brick Masonry (opens in a new tab) — Table 4: brick per 100 sq ft and mortar per 100 sq ft and per 1,000 brick for modular and non-modular sizes; add at least 5% to brick and 15–25% to mortar for waste.