Fire Pit Block Calculator
Count the wall blocks, caps, adhesive and sand for a round fire pit, from a 22, 36 or 48-inch steel fire ring or your own inside width.
A round fire pit takes more blocks than its width suggests, because the blocks sit outside the fire: every extra inch inside adds a ring of block around it. This counts the blocks row by row from the inside width, the space your steel fire ring needs, plus the caps, glue and sand.
Fire pit size
Sized by the steel fire ring that sits inside, or enter your own width.
Block size
Both cover the same area each. Narrower blocks take more to go around; taller ones make a taller pit.
Rows of blocks
Most fire pits are 3 rows of blocks plus the caps, about knee height.
Blocks to buy
45 blocks
15 a row, 3 rows high, about 20 in tall with caps
Counts match Pavestone's own fire pit kits. Set a steel fire ring inside so the flame stays off the blocks, and check your town's rules on how far a fire pit must sit from the house. 2026 figures.
๐กAbout this calculatorโผ
A block fire pit is one of the easiest backyard builds, and the store kits make it simpler still. Build bigger than the kit, though, and the count gets harder: the blocks sit outside the fire, so every extra inch of inside width adds a ring of block around it.
This counts it row by row. Pick the steel fire ring it will hold, 22, 36 or 48 inches (22 is the store-kit size), or enter your own inside width. Choose the block shape and how many rows high, and you get the blocks to buy, the caps and adhesive for the top, and the sand to fill the bottom.
The counts match the maker's kits. At the store-kit size, the calculator gives exactly what Pavestone's fire pit kits contain, so you can trust it when you go bigger.
Blocks sit on a circle outside the fire. The circle their faces sit on is the inside width plus two block depths. Divide its circumference by one block's face width and you have the blocks in a row. A taller 6-inch block is about 7ยพ inches across the face and 7 inches deep; a shorter 4-inch block about 11โ across and 6ยพ deep. Narrower faces take more blocks to go around, but each row of the taller block stands half again as high.
Checked against the kits. Pavestone's store kits are 40 inches across with about 23 inches inside. That circle takes 15 of the taller, narrower blocks a row or 10 of the shorter, wider ones, exactly what the kits contain: 45 for three rows of the taller block (20 inches high), or 30 of the shorter (14 inches high).
Caps, glue and sand. The wedge-shaped caps run about 4.3 inches each around a slightly bigger circle, 30 for the kit. One tube of construction adhesive covers about 30 feet of glue lines, about what the kit's three layers need. The kits call for about 4 bags of sand to fill the bottom, and bigger pits take more in proportion to their area.
Worked example. Room for a 36-inch steel ring, taller 6-inch blocks, three rows: the block faces sit on a 50-inch circle, about 157 inches around, so 20 blocks a row and 60 in all; 40 caps; 2 tubes of adhesive; about 10 bags of sand. It stands about 20 inches tall with the caps.
๐How it's calculatedโผ
Blocks a row = ฯ ร (inside width + 2 ร block depth) รท block face width, rounded. Taller 6-in block: 7 in deep, 7.75 in face. Shorter 4-in block: 6.75 in deep, 11.63 in face.
Blocks = blocks a row ร rows. Caps = ฯ ร (that circle + 3.5 in) รท 4.29 in, rounded up.
Adhesive = circumference (ft) ร rows รท 30, rounded up. Sand = 4 bags ร (inside width รท 23)ยฒ, rounded up.
22-inch ring (store-kit size, 23 in inside), taller blocks, 3 rows: 15 a row, 45 blocks, 30 caps, 1 tube, 4 bags, 20 in tall. Shorter, wider blocks: 10 a row, 30 blocks, 14 in tall. 48-inch ring, medium, 4 rows: 25 a row, 100 blocks, 48 caps, 3 tubes, 18 bags.
๐Sources:Pavestone โ RockWall Fire Pit Kit No. 02 instructions (45 medium blocks, 30 caps, insert, adhesive and sand),Pavestone โ RockWall Fire Pit Kit No. 01 instructions (30 small blocks, 30 caps),Pavestone โ RockWall Medium block cut sheet (dimensions),Pavestone โ RockWall Cap cut sheet (dimensions)
๐Finding your inputsโผ
Fire pit size: By the steel fire ring it holds. The 22-inch ring is the store-kit size, about 23 inches inside and 40 across. The 36- and 48-inch options leave room for those common fire ring sizes. For anything else, choose custom and enter the inside width, measured across the space where the ring sits.
Block shape: Taller, narrower blocks (6 inches tall, about 8 across) are the usual fire pit block; shorter, wider blocks (4 inches tall, about 12 across) make a lower pit. Each covers about the same area, so the narrower block takes more to go around but each row stands taller. Use tapered landscape wall blocks, the kind sold for fire pits and garden walls.
Rows of blocks: How many rows high before the caps. Three is typical, about knee height.
โ ๏ธSpecial situationsโผ
How many blocks for a 36-inch fire pit?
With the taller 6-inch wall blocks and room for a 36-inch steel ring, about 20 blocks a row, so 60 for three rows, plus 40 caps. With the shorter, wider 4-inch blocks it's about 13 a row, and three rows stand about 14 inches instead of 20. If "36 inches" is the outside size instead, that's smaller than the store kit, which is 40 inches across with about 23 inches inside.
How many blocks for a 48-inch fire pit?
With room for a 48-inch steel ring and the taller 6-inch blocks, about 25 blocks a row: 75 for three rows or 100 for four, plus 48 caps. A pit that size holds a big fire and seats a crowd around it.
Can I use cinder blocks for a fire pit?
This calculator counts landscape wall blocks, the kind fire pit kits use, because plain concrete cinder blocks aren't sold or rated for a fire. Whatever you build with, do what the store kits do: set a steel fire ring inside so the flame never sits against the concrete.
Do I need to glue fire pit blocks?
The kits do: construction adhesive between each layer keeps a circle of dry-stacked blocks from shifting as it heats and cools and as people lean on it. About one tube covers a store-kit pit; bigger or taller pits take two or three.
โCommon questionsโผ
How many blocks do I need for a fire pit?
For a store-kit pit, built around a 22-inch steel ring and about 40 inches across, 15 of the taller 6-inch blocks a row, so 45 for three rows, plus 30 caps. Bigger pits take more: room for a 36-inch ring takes about 20 a row, and room for a 48-inch ring about 25. Multiply by the rows you want; three is typical.
How big is a standard fire pit?
Store-bought block kits are about 40 inches across with roughly 23 inches inside, sized for a 22-inch steel ring, and three rows high, about 20 inches with caps. Homeowners building their own often go bigger, with room for a 36- or 48-inch fire ring.
Do I need a steel ring in a block fire pit?
It's strongly recommended, and every Pavestone fire pit kit includes one. The ring keeps the flame and the hottest coals off the concrete blocks, which is easier on them and makes the pit look finished.
What goes in the bottom of a fire pit?
The kits call for filling the pit with sand to about 5 inches below the top, with the steel ring set about an inch into it. That's about 4 bags for a store-kit pit and more for a bigger one, roughly in proportion to its area.
How many caps do I need for a fire pit?
One row of wedge caps around the top: about 30 for a store-kit pit (22-inch ring), 40 for room for a 36-inch ring and 48 for a 48-inch ring. Some kits stack two rows of caps for a taller look, which doubles the count.
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