Firewood BTU Calculator

Find out how many BTU you need to heat your home this winter. Enter your home details below for an instant estimate.

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Your location determines how cold your winters are and how much firewood you will need.

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Select your climate zone manually

Home Details

sq ft

Insulation quality

Stove type

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Our full heating calculator walks you through a step-by-step estimate with personalized species recommendations, cost analysis, and a seasoning timeline.

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How to Calculate BTU for Firewood Heating

Understanding your BTU requirement is the foundation of any firewood plan. BTU stands for British Thermal Unit — it is the amount of energy needed to raise one pound of water by one degree Fahrenheit. When applied to home heating, your annual BTU requirement tells you exactly how much energy your firewood needs to deliver over a full winter.

The formula is straightforward: take your home’s heated square footage, multiply by a heat-loss factor based on your insulation quality, multiply by the heating degree days for your climate zone, and divide by your stove’s combustion efficiency. The result is your total BTU requirement for the season.

Once you know your BTU number, divide it by the BTU per cord of your chosen wood species to find out how many cords you need. Our BTU comparison chart lists heat output for all 70 species, and the heating calculator walks you through a personalized estimate step by step.

BTU Requirements by Home Size

Approximate seasonal BTU needs assuming an EPA-certified stove at 72% efficiency.

Home SizeCold Climate (6,000 HDD)Moderate Climate (4,000 HDD)
1,000 sq ft58M BTU39M BTU
1,500 sq ft87M BTU58M BTU
2,000 sq ft117M BTU78M BTU
2,500 sq ft146M BTU97M BTU
3,000 sq ft175M BTU117M BTU

Values assume average insulation quality. Poor insulation can increase needs by 40–60%, while excellent insulation reduces them by 30–40%.

Frequently Asked Questions

How do I calculate BTU for heating with firewood?
Multiply your home’s square footage by the BTU loss rate per square foot (based on insulation quality) and by your climate zone’s heating degree days. Then divide by your stove’s efficiency to get the total BTU your firewood needs to provide. Our calculator above does this math instantly.
How many BTU do I need to heat a 1,500 sq ft house?
A 1,500 sq ft house with average insulation in a cold climate (6,000 HDD) typically needs 75 to 110 million BTU per season, depending on stove efficiency. An EPA-certified wood stove needs about 87 million BTU, while an open fireplace would need over 200 million BTU to deliver the same warmth.
How many BTU does a cord of firewood produce?
It depends on the species. Dense hardwoods like Osage Orange produce about 30 million BTU per cord, while Oak ranges from 22 to 26 million BTU. Softwoods like Pine produce 15 to 17 million BTU per cord. Check our BTU chart for all 70 species.
What is the difference between a BTU calculator and a BTU chart?
A BTU calculator estimates how many total BTU your home needs based on its size, insulation, climate, and stove type. A BTU chart lists the BTU output per cord for different firewood species. Use the calculator first to find your BTU requirement, then use the chart to pick the right species.
Does stove type affect how many BTU I need?
Yes, significantly. An EPA-certified wood stove operates at about 72% efficiency, meaning it converts 72% of the wood’s BTU into usable heat. An open fireplace runs at only 10 to 15% efficiency, requiring five to seven times more wood to produce the same warmth. Stove efficiency is the single biggest factor in how much firewood you will burn.

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