Firewood Calculator
Calculate how many cords of firewood to buy for the heating season.
Enter stove size, climate zone, and season length for an accurate supply estimate.
Firewood estimation relies on volume and heat output to determine how much wood you need for a full heating season.
A cord of firewood is the standard unit of measurement: a neatly stacked pile measuring 4 ft × 4 ft × 8 ft = 128 cubic feet. A face cord (or rick) is the same height and length but only as deep as one log (typically 16 inches), so it equals roughly one-third of a full cord.
Core formula: Cords Needed = (Heating Days × Daily BTU Demand) ÷ BTU per Cord
Where:
- Heating Days = the length of your heating season (typically 100–180 days depending on climate)
- Daily BTU Demand = your stove’s hourly output × average hours burned per day
- BTU per cord = varies by wood species (see below)
BTU output by stove size:
- Small stove (40,000 BTU/hr): ~2–3 cords/season
- Medium stove (60,000 BTU/hr): ~3–5 cords/season
- Large stove (80,000+ BTU/hr): ~5–7 cords/season
BTU per full cord by wood species:
- Oak: 24–28 million BTU (excellent, long burn)
- Hickory: 25–28 million BTU (very dense, slow burn)
- Maple: 22–25 million BTU (great all-rounder)
- Ash: 20–24 million BTU (splits easily, burns clean)
- Birch: 20–23 million BTU (good, burns faster than oak)
- Cherry: 18–22 million BTU (pleasant aroma)
- Pine: 15–18 million BTU (fast burn, more creosote risk)
- Poplar: 13–16 million BTU (low density, best for kindling)
Worked example: You heat your home 150 days/year using a medium stove (60,000 BTU/hr) burning 8 hours per day. You use seasoned oak (26 million BTU/cord).
Daily BTU = 60,000 × 8 = 480,000 BTU/day Season BTU = 480,000 × 150 = 72,000,000 BTU Cords needed = 72,000,000 ÷ 26,000,000 = ~2.8 cords
Add 10–15% buffer for cold snaps, and always buy seasoned wood (dried at least 6–12 months). Green wood loses 30–40% of its heat value.