Propane Heat Cost Calculator
Heating with propane comes down to three numbers you can actually know: what a gallon costs you, how much heat your home needs, and how efficiently your furnace turns fuel into warmth. This calculator prices your propane heat three ways: from a burner’s gallons-per-hour usage rate, from your home’s size and furnace efficiency, or from a single appliance’s BTU rating. Pick the method that matches what you know, and it returns gallons burned, BTU output, and daily, monthly and total cost.
Formulas: usage mode, cost = price × usage rate × hours × days; BTU mode, gallons = (sq ft × BTU/sq ft × heating days) ÷ (91,500 × efficiency); appliance mode, gallons = (BTU rating × hours × days) ÷ 91,500. Monthly cost is daily cost × 30. The appliance mode prices fuel input at the nameplate rating and does not apply a separate efficiency factor. A gallon of propane carries 91,500 BTU, the industry figure this calculator uses throughout.
Quick Answer
A 2,000 sq ft home heated 150 days a year with a 95% efficient furnace, needing 40 BTU per square foot, at $2.69 per gallon: the season takes 138.1 gallons of propane and costs $371.35 total, which is $2.48 per day and $74.27 per month. The calculator is pre-filled with this example: click Calculate heat cost to reproduce it.
Key takeaways
- Three modes, one answer: price from a burner’s gallons-per-hour, from home size and furnace efficiency, or from a single appliance’s BTU rating. Use whichever inputs you actually know.
- A gallon of propane carries 91,500 BTU. That single constant converts every BTU figure this calculator reports into gallons and dollars.
- The BTU-per-square-foot input is the average daily heating load per square foot across the heating season, not the peak hourly design load. Misreading it is the most common way to get a silly answer.
- Efficiency divides the gallons: a 95% furnace burns about 11% less propane than an 85% one for the same heat. The DOE will require 95% AFUE on new residential furnaces manufactured after late 2028.
- Monthly cost is daily cost × 30. Propane prices move by region and season, so always enter your supplier’s actual per-gallon price.
- Quick Answer
- How to use the propane heat cost calculator
- The formulas, mode by mode
- Worked example: the 2,000 sq ft home, checked three ways
- What the BTU-per-square-foot number really means
- Propane prices right now, and why your ticket matters more
- What competing calculators miss
- Related calculators
- Frequently asked questions
- Add This Calculator to Your Website
How to use the propane heat cost calculator
Choose the calculation method that matches what you know, fill in its fields, and click Calculate heat cost. Results stay hidden until you calculate.
- Pick a method: Usage-Based if you know a burner’s gallons per hour, BTU-Based for a whole home over a heating season (the default), or Appliance-Specific to price one device such as a fireplace or water heater.
- Enter your propane price: dollars per gallon from your supplier. $2.69 is pre-filled in the BTU method, near the recent U.S. residential average.
- Fill in the method’s inputs: the BTU method wants home size, heating season days, system efficiency and BTU per square foot; the appliance method auto-fills the BTU rating when you pick an appliance type.
- Read five numbers: gallons consumed, BTU output, daily cost, monthly cost and the total. The badge underneath translates the result into gallons per heating day and dollars per million BTU.
Home size caps at 20,000 sq ft, heating days at 365 and efficiency between 70% and 98%; the tool clamps out-of-range entries with a message rather than computing nonsense. Blank a required field and it stops with a message naming the method, exactly as the original tool did.
The formulas, mode by mode
Every mode converts heat into gallons with the same constant, 91,500 BTU per gallon of propane, then multiplies by your price. Only the starting point differs.
BTU-Based: gallons = (sq ft × BTU/sq ft × heating days) ÷ (91,500 × efficiency); cost = gallons × price
Appliance-Based: gallons = (BTU rating × hours/day × days) ÷ 91,500; cost = gallons × price
The BTU mode is the interesting one: the numerator is the season’s total heat demand, and the denominator shrinks it by efficiency, because a 95% furnace needs fewer gallons of fuel energy to deliver the same heat. Daily cost is the total divided by heating days, and monthly cost is daily cost × 30, a flat 30-day month rather than a calendar proration. Note what the appliance mode does not do: it prices the nameplate fuel input directly and applies no separate efficiency factor, so treat its answer as the fuel the rating implies.
Worked example: the 2,000 sq ft home, checked three ways
The pre-filled example is a 2,000 sq ft home, 150 heating days, a 95% efficient furnace, 40 BTU per square foot, propane at $2.69 per gallon. Running it gives 138.1 gallons and $371.35 for the season.
The same three modes, run on different inputs, produce the checks below. Every row is a real run of this calculator.
| Mode and inputs | Gallons | BTU output | Total cost |
|---|---|---|---|
| BTU: 2,000 sq ft, 150 days, 95%, 40 BTU/sq ft, $2.69 | 138.1 | 12,000,000 | $371.35 |
| Usage: $2.50, 1.5 gal/h, 6 h/day, 20 days | 180.0 | 16,470,000 | $450.00 |
| Appliance: furnace 100,000 BTU/h, 8 h/day, 30 days, $2.50 | 262.3 | 24,000,000 | $655.74 |
The usage row is the simplest sanity check in the table: 1.5 × 6 × 20 = 180 gallons, and 180 × $2.50 = $450.00 exactly. The appliance row shows what a furnace costs when it actually fires eight hours a day for a month: 262.3 gallons, $655.74, or $21.86 per firing day.
What the BTU-per-square-foot number really means
It is the average daily heating load per square foot across your whole heating season, not the peak hourly load on the coldest night. The tool multiplies it by square footage and by heating days, so the number you enter must already be a per-day average.
That distinction matters because 30-60 BTU per square foot is also the range people quote for hourly design loads. Enter a design-day hourly figure here and the answer comes out roughly 24 times too high. As a reality check, compare the gallons against the rule of thumb the industry uses: whole-home heating typically runs 200 to 1,200 gallons a year depending on climate and home size. If the calculator says 138 gallons for a 150-day season in a mild climate, that is plausible; if it says 40 gallons for a Minnesota winter, your BTU-per-square-foot figure is too low.
The honest way to pick the number: start at 30-40 for a well-insulated home in a moderate climate, 40-50 for average insulation or colder regions, and 50-60 for drafty homes or severe winters, then compare the result against last winter’s actual propane deliveries. Your delivery tickets are the ground truth this estimate should be calibrated against.
Propane prices right now, and why your ticket matters more
National averages are a starting point, not your price. The EIA’s weekly heating-fuel survey put the U.S. residential average at $2.69 per gallon for the week ending October 19, 2026, and the EIA’s winter analysis notes that propane prices typically climb as heating season draws down inventories. State prices spread widely around the average: the Midwest usually pays least, New England most, and the EIA publishes state-level weekly prices so you can check yours.
Two price facts that change the math: propane is cheapest to buy in summer when demand is low, and delivery tickets in rural areas often beat the state average because the supplier’s route density is what you are really paying for. Enter the price on your last ticket, not the national average, and the estimate becomes yours instead of everyone’s.
What competing calculators miss
Propane calculators online tend to do exactly one thing:
- Usage-only tools: one formula, price × gallons/hour × hours × days, with a worked example and nothing else. No efficiency, no appliance ratings, no seasonal view. If you don’t know your burner’s gallons per hour, you are stuck.
- BTU-only tools: (BTUs ÷ (BTU per gallon × efficiency)) × price, sometimes with a slightly different BTU-per-gallon constant (91,333 instead of this page’s 91,500). Fine arithmetic, but a single mode and no way to price one appliance.
- Consumption estimators: they estimate gallons and stop, leaving you to multiply by your price yourself, or they compare fuels without pricing your propane at all.
- University fuel-comparison tables: excellent reference formulas for comparing propane against oil, gas and electricity on a dollars-per-million-BTU basis, but reference tables, not calculators.
- The gap this page fills: all three starting points in one tool, with appliance BTU ratings auto-filled from real equipment ranges (furnace 100,000, boiler 80,000, fireplace 30,000 and the rest), efficiency applied the way AFUE actually works, and the answer broken into gallons, BTU, daily, monthly and seasonal cost instead of a single total. Plus the honest disclosures rivals skip: what the BTU-per-square-foot figure really is, that monthly means daily × 30, and that the appliance mode prices nameplate input without a separate efficiency factor.
Related calculators
Once you know the gallons, the propane volume calculator converts between gallons and pounds, which is how tanks and deliveries are often quoted. If you are comparing fuels rather than pricing propane alone, the cost of energy calculator puts propane, electricity and other fuels on the same dollars-per-heat basis. The heating rate calculator works the related problem of what a heating system costs per unit of time, and the fuel adjustment factor calculator handles the surcharge math utilities add when fuel prices move.
Frequently asked questions
It depends on home size, climate, furnace efficiency and your local price. As a worked example here: a 2,000 sq ft home heated 150 days with a 95% efficient furnace at $2.69 per gallon costs $371.35 for the season, or $74.27 per month. Whole-home heating typically runs 200 to 1,200 gallons a year depending on climate and home size.
91,500 BTU per gallon. That is the industry figure this calculator uses in every mode. You will occasionally see slightly different figures in older references (one university fuel table cites 92,500), but 91,500 matches the EIA’s barrel conversion and is the standard most calculators use.
Use Usage-Based if you know your burner’s gallons-per-hour consumption, BTU-Based for a whole home over a heating season (it needs home size and furnace efficiency), and Appliance-Specific to price one device such as a fireplace or water heater. All three use the same 91,500 BTU per gallon constant.
It is the average daily heating load per square foot across the heating season, not the peak hourly load on the coldest night. The tool multiplies it by square footage and by heating days, so a design-day hourly figure entered here inflates the answer roughly 24 times. The typical input range is 30-60.
Because gallons = heat needed ÷ (91,500 × efficiency). A 95% efficient furnace converts 95% of each gallon’s energy into heat, so it needs fewer gallons for the same warmth: about 11% less than an 85% unit. Efficiency is your furnace’s AFUE rating, found on its yellow EnergyGuide label.
Monthly cost is daily cost × 30, a flat 30-day month. It is not prorated to calendar months, so treat it as a budgeting figure rather than an exact bill for February.
No. The appliance mode prices the nameplate BTU input rating directly and applies no separate efficiency factor. If you want efficiency-adjusted gallons for a whole home, use the BTU-based method instead.
No. Every calculation runs locally in your browser. Nothing you type is sent to a server or stored.
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References
- U.S. Energy Information Administration. U.S. propane prices have traded higher so far this winter compared with last winter. Accessed October 23, 2026.
- U.S. Energy Information Administration. Petroleum & Other Liquids: weekly propane price data. Accessed October 23, 2026.
- Bartok, J. W., University of Connecticut Extension. Comparing Fuel Costs. Accessed October 23, 2026.
- U.S. Department of Energy. DOE Finalizes Energy Efficiency Standards for Residential Furnaces. Accessed October 23, 2026.
- Trane. What Does AFUE Stand For? Accessed October 23, 2026.
- Paraco Gas. Propane Home Heating: What To Know Before Winter. Accessed October 23, 2026.
- One Hour Heating & Air Conditioning. Electric vs. Propane Heat Cost and Maintenance Comparison. Accessed October 23, 2026.