Firewood Calculator
Estimate how many cords of firewood you will burn in a heating season.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Planning estimate from heated area, broad climate and insulation factors, stove efficiency and wood category. The model assumes dry full cords with representative heat values; species, moisture, stacking and building heat loss vary. It is not an energy audit or heating-system sizing calculation.
Worked example
calculated with the default values below
Heated floor area 1,800 sq ft · Insulation quality Average · Climate Moderate winter · Stove efficiency 70 % · Months of heating 6 months · Price per full cord 350 $ · Wood type Mixed hardwood Seasonal heat demand 72.0 million BTU · Cords needed 5.14 cords · Cost for the season 1,800.00 $ · Estimated gross heat per dry cord 20.0 million BTU · Cords per month 0.857 cords · Estimated stacked volume (128 cu ft per full cord) 658 cu ft
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
C = (A × c × i ÷ 1000) ÷ (B × e ÷ 100); V_stack = 128 × C
- A
- heated area (sq ft)
- c
- climate factor
- i
- insulation factor
- B
- million BTU per cord
- e
- stove efficiency (%)
- C
- cords needed
Illustrative dry-cord heat assumptions: softwood 16, mixed 20, hardwood 24 million BTU; actual species and moisture content vary. Climate/insulation factors are planning estimates, not a building heat-loss calculation. A full cord is 128 cu ft stacked; monthly cords = total ÷ heating months.
Frequently asked questions
What do the cord and heat estimates assume?
A full cord is a neatly stacked 4 × 4 × 8 ft pile, or 128 cubic feet including air space. This model uses illustrative dry-wood values of 16, 20 and 24 million BTU per cord for softwood, mixed and dense hardwood, then applies stove efficiency. Real heat varies by species and moisture; the climate and insulation factors are planning assumptions, not a home energy audit.