Propane Usage Calculator

Overview

How to use this calculator

1. List the propane appliances you want to model (for example, furnace, water heater, range, dryer, or shop heater) and note the BTU/hr rating on each nameplate or in the manual.
2. Add up the BTU/hr values for appliances you expect to run at the same time, or choose one major load to model individually if they rarely overlap.
3. Enter the combined BTU per hour in the Total BTU per hour field, then enter the average number of hours per day that combined load runs. For heating, you might start with an average based on past bills or thermostat run-time data.
4. Enter the number of days per month you expect this pattern (for example, 30 days for a typical winter month or fewer days if you are planning a shorter project or trip).
5. Enter your current propane price per gallon from your supplier quote or recent bill.
6. Review the estimated daily and monthly BTU use, gallons burned, and cost. Adjust BTU load, hours per day, days per month, or price to reflect different scenarios such as colder weather, more occupants, or price changes.

Inputs explained

Total BTU per hour

The combined BTU/hr rating of the propane appliances you are modeling. You can use a single appliance’s BTU/hr or sum the ratings for multiple appliances that are likely to run simultaneously (for example, a furnace and water heater during cold mornings).

Hours per day

The average number of hours per day the combined load runs. This does not need to be continuous; cycling on and off for a total of 4 hours per day is treated the same as a continuous 4‑hour run for energy purposes.

Days per month

The number of days in a month you expect this usage pattern. For winter heating, you might use 30 days; for a specific project or trip, you might enter only the days when the equipment will actually run.

Price per gallon

The amount you pay per gallon of propane from your supplier, including any delivery or service charges if they are effectively rolled into the per‑gallon price. Update this field when your supplier adjusts rates.

When to use it

• Estimating how many gallons and how much cost to expect during a winter month when your furnace, water heater, and other propane appliances see heavy use.
• Budgeting propane for a workshop or garage heater to understand how much it will cost to keep the space warm for a given number of hours per day.
• Planning generator or temporary heat usage on a construction site by estimating how long a given tank size will last at a specific BTU load.
• Checking whether your existing tank capacity is sufficient for a planned trip in an RV or cabin by approximating daily gallons and comparing to usable tank volume.

Tips & cautions

• If your appliances rarely run all at once, consider modeling them separately or using a lower combined BTU/hr value to avoid overestimating consumption.
• Use historical bills as a sanity check. If your modeled gallons are dramatically different from what you’ve used in past months with similar weather, revisit your BTU and runtime assumptions.
• For critical loads like whole‑home generators or primary heating in very cold climates, build in extra buffer so that usage spikes during cold snaps or long outages do not leave you short on fuel.
• Keep in mind that tank capacity is not fully usable—most tanks should not be run all the way to 0% for safety and equipment reasons. When planning, assume a usable range (for example, from 80% down to 20%).
• Propane energy content can vary slightly by supplier and conditions, and combustion efficiency of appliances is not perfect. Treat the 91,500 BTU/gal factor as an average rather than an exact measurement.
• The model assumes a constant BTU/hr draw during the hours you specify. In reality, many appliances modulate or cycle, which can reduce actual consumption compared with the worst‑case continuous assumption.
• It does not account for appliance efficiency. Real systems lose some energy up the flue or through distribution losses; the calculator focuses on fuel energy input, not delivered heat.
• Line losses, tank pressure variations, and cold‑weather delivery issues are not modeled. For mission‑critical planning, you should factor in additional safety margins.
• Price per gallon is treated as constant. If your supplier uses tiered pricing, seasonal surcharges, or delivery minimums, you may want to adjust the input price to reflect your effective average cost.

Worked examples

Deep dive

FAQs

How do I find BTU/hr ratings for my appliances?

Most propane appliances list their BTU/hr input rating on a nameplate or in the installation manual. Look near the burner compartment, gas valve, or on a label inside the access panel.

What if my appliances don’t run at the same time?

If appliances rarely overlap, you can either model each one separately and add their gallons, or use a lower combined BTU/hr value that better reflects your typical simultaneous load.

Does this account for appliance efficiency or tank losses?

No. The calculator focuses on fuel energy input based on BTU ratings and does not adjust for combustion efficiency, duct losses, or tank/line losses. For a more conservative estimate, you can slightly increase BTU/hr or hours per day.

How often should I update the price per gallon?

Any time your supplier changes rates or you sign a new contract. Propane pricing can be seasonal or volume-based; using your latest effective price will make the cost outputs more accurate.

Can I use this for natural gas?

This tool is tuned for propane at ~91,500 BTU per gallon. Natural gas is usually billed per therm (about 100,000 BTU). You could adapt the logic, but for accurate natural gas billing comparisons you’d want a therm-based calculator.

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