Seven ways to size the pit itself — diameter, seating, brick ring, propane burn time, and safety clearances. Free, private, runs 100% in your browser.
100% client-side — no data leaves your device
Scope: this tool sizes the fire pit (diameter, bricks/blocks, seating circle, BTU, clearances) — not the patio around it. Sizing the patio itself? See the patio size calculator.
Based on published size bands: Small 24–36 in (2–4 people), Medium 36–44 in (4–6), Large 44–60 in (6+).
Inside diameter = outside diameter minus twice the wall thickness. Standard wall: 6 in.
Uses the smaller dimension. Guide: 10×10 ft → 24–36 in pit; 12×12 → 36–44; 16×16 → 44–52; 20×20 → 52–60.
Wall count = courses × circumference ÷ (brick length + gap). Cap ring = circumference ÷ (brick width + gap). Check: a 36 in pit ≈ 80 bricks.
Comfortable spacing ≈ 30 in per chair; 24 in is snug. Keep 7–8 ft clear around the pit for seating and safety.
Burn time = tank BTU ÷ burner BTU rating. A 20-lb tank holds ≈ 430,000 BTU. Anchors: 30 in/40k ≈ 11 h, 36 in/50k ≈ 9 h, 48 in/65k ≈ 6.5 h.
Code reference: IFC 307.4.2 recreational fires ≥ 25 ft; 307.4.3 portable ≥ 15 ft (model IFC — local adoptions can renumber sections). Manufacturer guidance is often 10 ft — below code. Always check local code/HOA.
Frequently asked questions
What is the standard fire pit size?
The most common backyard sweet spot is 48 in outside diameter by 36 in inside diameter by 16 in tall, built from four courses of blocks (about 48 blocks total). Common size classes are Small 24-36 in for 2-4 people, Medium 36-44 in for 4-6 people, and Large 44-60 in for 6 or more.
How many people fit around a fire pit?
Plan on roughly one person per 7 in of pit diameter: a 36 in pit seats about 5, a 44 in pit about 6, and a 48 in pit about 7. Published bands are 24-36 in for 2-4 people, 36-44 in for 4-6, and 44-60 in for 6 or more.
How many bricks do I need for a 36-inch fire pit?
About 80 standard 8 by 4 by 2.25 in bricks: roughly 54 for the walls (4 courses of about 13-14 bricks) plus about 26 for a cap ring radiating inward, then add 10% waste. The estimator above uses circumference divided by (brick length + mortar gap), times the number of courses.
How far should a fire pit be from the house?
Model codes (IFC Section 307.4.2) require recreational wood fires to be at least 25 ft from structures and combustibles, and portable outdoor fireplaces at least 15 ft (307.4.3). Many manufacturers quote 10 ft for their units, which is below the code figure, so always check your local fire code and HOA first. Section numbers are per the model IFC — confirm with your local adopted edition, since local amendments can renumber sections.
How long does a 20-lb propane tank last on a fire pit?
A 20-lb tank holds about 430,000 BTU. Divide by the burner rating: a 30 in pit at 40,000 BTU per hour runs about 10.8 hours, a 36 in pit at 50,000 BTU per hour about 8.6 hours, and a 48 in pit at 65,000 BTU per hour about 6.6 hours. Turning the flame down extends runtime.
Can I put a fire pit on a patio or wood deck?
Gas and portable fire pits are commonly used on paver or concrete patios when the manufacturer allows it and local code permits. Wood-burning pits on a wood or composite deck are generally not recommended because of embers and heat. Check the manual and local code before you buy.
Wood or gas: does the size I need change?
Yes. Wood fires throw sparks and need a larger safety buffer plus a spark screen, so many guides suggest sizing up. Gas flames are controllable and the effective heat zone follows the burner, so smaller diameters work on tight patios.
How tall should a fire pit be?
Most guides recommend 12-18 in of wall height. The common DIY build is 16 in tall (four courses), which keeps flames contained while letting heat radiate out to seated guests.
How much space do I need around a fire pit for chairs?
Allow about 30 in from the pit edge to the front of each chair, then 30 in for the chair itself and 24 in of walkway behind. For a 36 in pit that is an 8 ft seat circle and about 12.5 ft of total leisure width; guides typically cite 8-12 ft of total width.
Do I need a permit for a fire pit?
It depends on where you live. Many cities restrict open burning or require permits and inspections, and HOAs often have their own rules. Check local fire code before building or burning. This calculator is a planning estimate, not a code ruling.
We use cookies and third-party services (including Google AdSense) to personalize content, analyze traffic, and serve relevant ads. By clicking "Accept", you consent to our use of cookies as described in our Privacy Policy.
Report an issue
2 taps, no typing needed — diagnostics are sent automatically.