This calculator sizes the burner pan from a heat-balance approach, using your target heat output, a chosen design heat flux, and an efficiency factor.
- Round pan: Diameter = √(4 × Area ÷ π)
- Square pan: Side = √(Area)
- Depth: Depth = Base Dimension × Depth Ratio
- Clearance: Add your safety clearance to diameter/side.
Heat flux is the biggest driver. If your burner runs cooler or outdoors in wind, reduce efficiency or choose a lower flux.
- Enter your target heat output (BTU/hr) for the garden task.
- Select fuel and pan shape that match your setup.
- Set efficiency for your environment; wind lowers it.
- Pick a heat flux value; start near 40,000 for propane.
- Click calculate, then download CSV or PDF if needed.
| Scenario | Heat (BTU/hr) | Flux (BTU/hr/ft²) | Eff. | Shape | Base Dim (in) | Depth (in) |
|---|---|---|---|---|---|---|
| Small debris drying | 45,000 | 35,000 | 0.70 | Round | 19.7 | 3.3 |
| Weed-control heat station | 65,000 | 40,000 | 0.70 | Square | 20.7 | 3.7 |
| Outdoor windy setup | 90,000 | 35,000 | 0.60 | Round | 28.8 | 4.6 |
Example values assume modest clearance and shallow depth ratios. Your setup may require adjustments for wind, shielding, and burner design.
This calculator uses a design heat flux range of 10,000 to 120,000 BTU/hr/ft², with many garden burners working best near 30,000–45,000. For the same heat target, doubling flux cuts required pan area roughly in half. If your flame spreads unevenly, lower flux to avoid hot spots and edge flare.
Efficiency is a practical factor for wind, open-air mixing, and heat escaping above the pan. Typical planning values are 0.65–0.75 for sheltered work, and 0.55–0.65 for exposed conditions. A 0.70 to 0.60 drop increases required area by about 17%, which can change a borderline pan into an undersized one.
Round pans convert area to diameter using π, while square pans use the square root of area for side length. Clearance is added to the final diameter or side, not the area. A 2-inch total clearance is a common starting point, but 3–6 inches is helpful when edges are near mulch, boards, or pots.
Depth is estimated as base dimension times a ratio, typically 0.15–0.22 for shallow pans. Shallow depth reduces slosh and improves surface exposure, while deeper pans increase volume and weight. The volume output is an awareness metric only; do not use it for fuel storage or transport planning.
The CSV download captures heat output, flux, efficiency, shape, and recommended dimensions for quick comparisons between garden tasks. The PDF report is useful for work orders or maintenance logs, especially when you adjust flux after field testing. Keep notes on weather and shielding, then rerun the calculator to standardize safe, repeatable results over time.
1) What heat flux value should I start with?
For many garden burners, start around 35,000–45,000 BTU/hr/ft². If flames feel weak or uneven, lower flux to increase pan area and improve stability outdoors.
2) Why does efficiency change the size so much?
Efficiency accounts for heat lost to wind and open-air mixing. When efficiency drops, the same heat target needs more area to deliver usable heat at the pan surface.
3) Should I choose a round or square pan?
Choose the shape that matches your available hardware and workspace. Round pans distribute heat smoothly, while square pans can fit tight corners and straight edges.
4) How do I set safety clearance?
Clearance is added to the final diameter or side length. Use 2 inches for controlled, nonflammable surroundings, and increase to 3–6 inches near mulch, wood, or pots.
5) Is the depth result required for performance?
Depth is a guidance value for stable, controllable pans. Shallow depths usually improve surface exposure, while deeper pans add weight and volume without guaranteeing better heat delivery.
6) Why does the PDF not download until after calculating?
Downloads use the computed result. Run the calculation first, then use the CSV or PDF buttons shown above the form to export the values and assumptions.