Calculator
Enter your fire table details. On submit, you’ll see recommended side and overhead clearances, plus optional PASS/FAIL checks against your measured space.
Formula used
- Heat conversion: if you enter kW, BTU/hr = kW × 3412.142.
- Dynamic side clearance: DynamicSide = 24 + 0.12×√BTU + 0.5×FlameHeight.
- Dynamic overhead clearance: DynamicOver = 72 + 0.15×√BTU + 0.8×FlameHeight.
- Environmental multiplier: Mult = Wind × Setting × Materials × Guard.
- Required from burner edge: ReqBurner = max(BaselineMin, DynamicSide×Mult).
- Required overhead: ReqOver = max(BaselineMinOver, DynamicOver×Mult).
- Safety margin: Req = Req × (1 + Safety%/100).
- Table edge requirement: ReqTable = max(0, ReqBurner − Setback).
How to use this calculator
- Select a unit system and enter your fire table heat output.
- Enter typical flame height at your usual setting.
- Choose table shape and add table and burner dimensions.
- Pick wind exposure, placement type, and nearby material mix.
- Optionally add your baseline minimum clearances and a safety margin.
- Enter measured side/overhead distances to get PASS/FAIL checks.
- Press Calculate to view results above the form.
Clearance targets for garden layouts
Fire tables become part of the planting plan, so clearances should be treated like a buffer zone. Use the calculator to estimate a minimum side distance from the table edge to any combustible items, including mulch, wicker, cushions, and dry leaves. Keep walk paths outside the buffer so guests do not brush past the flame area.
Heat output and flame height effects
Heat output is the strongest driver of recommended spacing. Higher BTU/hr (or kW) increases radiant heat and raises the suggested side and overhead clearances. Flame height adds another layer: tall flames can lick upward toward branches and pergolas and can also throw more heat sideways. Measure flame height at your typical setting, not maximum.
Wind and enclosure adjustments
Wind shifts flames and pushes heat toward nearby surfaces. The calculator applies a wind factor so a breezy deck or corner yard gets larger recommendations than a calm lawn. Covered patios and partly enclosed areas also increase risk because heat can accumulate and airflow may be uneven. Use the setting option to reflect walls, roofs, or fencing that can trap heat.
Materials, screens, and setbacks
Nearby materials matter as much as distance. Stone and metal tolerate heat better than wood, plastic, or resin furniture. A guard screen can reduce small ember travel, but it should not be used to justify tight spacing; the tool applies only a modest reduction. Setback converts clearance from burner edge to table edge using your table and burner dimensions, which improves accuracy for different designs.
Interpreting results and planning actions
Read the required side and overhead values as planning minimums, then add extra room for pets, children, and moving chairs. If your measured clearances fail, relocate the unit, switch to non‑combustible furnishings, prune overhanging branches, or lower the flame setting. Save results as CSV or PDF to share with installers and to document your garden safety plan. Recheck spacing after seasonal landscaping changes, especially when adding planters or new seating.
FAQs
What distance should I keep from shrubs and mulch?
Treat dry plants and mulch as combustible. Use the calculated side clearance from the table edge, then add extra space if foliage is brittle or windy. A gravel or paver ring around the unit helps reduce risk.
Do I enter the burner size or the table size?
Enter both. The burner dimensions are used to compute setback from burner edge to the table edge. That converts the burner‑based clearance into a practical distance you can measure from the outside of the table.
How do I use kW ratings?
Select kW in the heat unit menu and enter the listed rating. The calculator converts kW to BTU/hr internally, then applies the same clearance model, factors, and safety margin to produce distances in your chosen units.
Why are overhead clearances often larger?
Heat rises and can accumulate under roofs, pergolas, and tree canopies. Overhead spacing protects branches, ceiling finishes, and lighting, and it reduces the chance of discoloration, drying, or ignition when flames surge.
Can a glass wind guard reduce required spacing?
A guard may limit flame movement and ember travel, but it does not eliminate radiant heat. The calculator applies only a small reduction. Always follow your manufacturer guidance and keep combustible furniture and décor outside the recommended buffer.
What if my space fails the PASS/FAIL check?
Lower the flame, move the table to a more open spot, or replace nearby items with non‑combustible materials. Prune overhangs and increase ventilation. Recalculate after changes and keep a larger margin for gatherings.
Example data table
Sample planning scenarios. Replace with your measurements and manual values.
| Scenario | Heat | Table / Burner | Setting | Recommended side | Recommended overhead |
|---|---|---|---|---|---|
| Small patio corner | 20,000 BTU/hr | 36" round / 18" burner | Covered patio, mixed materials | ~40–50 in from table edge | ~90–105 in |
| Open lawn seating | 50,000 BTU/hr | 48" round / 24" burner | Open air, combustible nearby | ~55–70 in from table edge | ~105–125 in |
| Windy deck setup | 65,000 BTU/hr | 60"×32" / 36"×12" | Open air, windy, combustible | ~65–85 in (ends may differ) | ~120–140 in |