Calculator
Enter hopper capacity and pellet consumption. Add a reserve so you never fully empty the hopper. Use duty cycle if the feeder runs intermittently.
Example data table
Typical consumption varies by cooker design, weather, and load. Use this as a starting point, then refine using your measured average.
| Setting / Use | Approx. temp | Typical consumption (lb/hr) | Notes |
|---|---|---|---|
| Smoke / Idle | 160–190 | 0.5–0.9 | Longest runtime, mild heat. |
| Low cook | 200–230 | 0.8–1.3 | Good for slow garden warmth. |
| Medium cook | 240–300 | 1.2–2.0 | Most common mixed use. |
| High heat | 325–400 | 2.0–3.5 | Wind increases burn noticeably. |
| Very high | 425–500 | 3.0–5.0 | Short runtime, strongest output. |
Formula used
The calculator converts everything to a consistent mass unit internally, then applies reserve and duty cycle.
Reserve_mass = Hopper_capacity × (Reserve_percent / 100)
Usable_mass = Hopper_capacity − Startup_allowance − Reserve_mass
Effective_rate = Consumption_rate × (Duty_cycle_percent / 100)
Runtime_hours = Usable_mass / Effective_rate
If you select a low–high range, the shortest runtime uses the high rate, and the longest runtime uses the low rate.
How to use this calculator
- Measure your hopper capacity in lb or kg.
- Enter your average consumption rate, or a low–high range.
- Set a reserve percent so you avoid running empty.
- Add startup allowance if your unit uses extra pellets at ignition.
- Use duty cycle if your feeder runs intermittently.
- Optionally enter bag price and weight to estimate cost.
- Press Submit to view runtime and download reports.
Professional notes for pellet hopper runtime planning
1) Why runtime planning matters
In garden heating or outdoor cooking, runtime estimates help you avoid flame-outs and unstable temperatures. A hopper that empties mid-session can cool quickly, waste fuel during recovery, and interrupt your schedule. This calculator converts capacity and consumption into predictable hours and days, so you can plan refills calmly.
2) Key inputs and what they mean
Hopper capacity is the total mass of pellets available. Startup allowance represents ignition or priming pellets that do not contribute to steady operation. Reserve percent is a safety buffer left unused to reduce auger starvation and keep fines from dominating the last portion of fuel. Duty cycle adjusts the burn rate when feeding is intermittent.
3) Interpreting range results
Many pellet devices vary their feed rate with temperature demand and wind exposure. Selecting the low–high range produces a runtime band. The shortest runtime corresponds to the high burn rate, while the longest runtime uses the low burn rate. If your results feel wide, measure burn over one hour at two settings to tighten the range.
4) Using duty cycle and reserve wisely
A duty cycle of 60% means the auger feeds at your stated rate for only 60% of the time, increasing runtime accordingly. Reserve is best set between 5% and 20% for practical refilling; larger reserves improve reliability but reduce usable fuel. If usable pellets become negative, lower reserve or startup allowance, or increase hopper capacity.
5) Cost and refill scheduling
When bag price and weight are provided, the calculator estimates usable-fill cost and (for single-rate mode) cost per hour. Use the formatted runtime (hours and minutes) to set a refill reminder at 70–85% of the estimated runtime. For example, a 12-hour estimate suggests checking pellets around the 9th to 10th hour for consistent performance.
FAQs
1) What burn rate should I enter?
Use your measured average pellets per hour. If unknown, start with a low–high range from your typical setting, then refine after a one-hour test run.
2) Why does reserve percent reduce runtime?
Reserve is a safety buffer left unused. Keeping pellets above the auger pickup reduces feed interruptions and avoids running the hopper fully empty.
3) When should I use duty cycle?
Use duty cycle if the feeder or burner runs intermittently. Example: if it runs about half the time, enter 50% to reflect the effective average rate.
4) What is “startup allowance”?
Startup allowance accounts for ignition or priming pellets that are consumed before steady operation begins. Enter zero if you do not observe a meaningful startup burn.
5) Why are my range results “short to long”?
The high burn rate consumes pellets faster, giving the shortest runtime. The low burn rate consumes slower, giving the longest runtime.
6) Can I estimate cost without bag data?
Runtime works without cost inputs. For cost estimates, enter bag price and bag weight so the calculator can compute cost per unit mass.
7) How often should I re-check my burn rate?
Re-check after major changes such as different pellet brand, strong seasonal weather shifts, or new operating settings. A quick one-hour measurement usually restores accuracy.