Cost Calculator AI
Home & LivingMulti-Fuel Thermal Model

Heating Cost Calculator

Estimate home heating expenses across natural gas, electric resistance, heat pump, heating oil, and propane systems using either direct fuel usage or modeled BTU heat demand.

Heating System & Demand Inputs

Select Display Currency:
AFUE% or COPร—100
$
Modeled Heat Demand
Estimated Heating Cost
$132.39

91.30 Therms consumed over 30 days

Daily Heating Cost$4.41
Delivered Heat Output8.40 MMBtu
Assumptions Used:
Modeled from BTU/h output, run hours, and efficiency.

Heating Energy & Cost Formula

Required Fuel Units = (Heat Demand BTU/h ร— Hours/Day ร— Days) รท (Efficiency Ratio ร— BTU per Fuel Unit)
  • Direct Usage Mode: Multiplies user-entered fuel units (Therms, kWh, or Gallons) directly by the unit energy price.
  • Modeled Heat Demand Mode: Divides total delivered BTU heat demand by system efficiency (AFUE% or COP) and fuel energy density.
  • Fuel Energy Densities: Natural Gas = 100,000 BTU/Therm; Electricity = 3,412.14 BTU/kWh; Heating Oil = 138,500 BTU/gal; Propane = 91,500 BTU/gal.

Step-by-Step Worked Example

Scenario: Running a 40,000 BTU/h natural gas furnace (92% AFUE) for 7 hours/day over 30 days

Calculation Steps:

  1. Total Delivered Heat = 40,000 ร— 7 ร— 30 = 8,400,000 BTU (8.40 MMBtu)
  2. Required Input Energy = 8,400,000 รท 0.92 = 9,130,435 BTU (91.30 Therms)
  3. Estimated Heating Cost = 91.304 Therms ร— $1.45 = $132.39
Result: The 30-day heating cost is $132.39 ($4.41 per day).

How to Use This Calculator

  1. 1Choose your heating system type (Natural Gas, Electric Baseboard, Heat Pump, Heating Oil, or Propane).
  2. 2Select whether you are entering Direct Fuel Usage from a meter or Modeling Heat Demand from BTU/h and efficiency.
  3. 3Enter your fuel unit price and the number of days in the heating period.

Assumptions & Limitations

  • Clearly separates metered fuel usage from modeled thermal demand.
  • For electric heat pumps, enter efficiency as COP ร— 100 (e.g., COP 2.8 = 280% efficiency).

Frequently Asked Questions

How do I enter heat pump efficiency in this calculator?

Air-source heat pumps move heat rather than creating it, achieving 200% to 350% efficiency (COP of 2.0 to 3.5). Enter 280% for a heat pump with a Coefficient of Performance (COP) of 2.8.

What is the difference between input BTU and output BTU on a furnace?

Input BTU is the raw fuel burned per hour, while output (bonnet) BTU is the usable heat delivered into your home after accounting for AFUE flue losses (Output BTU = Input BTU ร— AFUE%).

Why does electric resistance heating cost more per MMBtu than natural gas in many areas?

1 Therm of natural gas delivers 100,000 BTU, which is equivalent to the raw thermal energy of 29.3 kWh of electricity. Even at 100% electric resistance efficiency, 29.3 kWh at $0.17/kWh costs $4.98 per 100,000 BTU.

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