What this calculator does
Firewood need is burn rate multiplied by hours per day multiplied by heating days. Three quarters of a cubic foot an hour over six hours a day for 120 days is 540 cubic feet, which is 4.22 full cords.
A full cord is a precise unit: 128 cubic feet, stacked 4 feet by 4 feet by 8 feet. A face cord is not precise at all, since it is one row of whatever length the logs happen to be. At 16 inch logs a face cord is a third of a full cord, which is how the same word covers very different quantities of wood.
The formula
The volume needed is the burn rate multiplied by the hours per day and the number of heating days. That is divided by 128 cubic feet to give full cords, and by a third of that to give face cords at 16 inch log length. The stack height figure shows how tall an 8 foot long row would need to be, which is usually the point at which multiple rows become necessary.
| Term | Meaning |
|---|---|
| Full cord | 128 cubic feet: a stack 4 ft high, 4 ft deep and 8 ft long. |
| Face cord | One row, 4 ft high and 8 ft long, of whatever depth the logs are. At 16 inch logs this is a third of a full cord. |
| Burn rate | Cubic feet of wood consumed per hour, which depends on the stove and how hard it is run. |
| Seasoning | Drying split wood for six to twelve months, which is what makes it burn efficiently. |
The inputs explained
| Field | What to enter |
|---|---|
| Stove burn rate (ft³/hour) | Burn rate in cubic feet per hour. |
| Hours burning per day | Hours burning per day. |
| Heating days in the season | Heating days in the season. |
| Stack length available (ft) | Length of the stacking row in feet, used for the stack height figure. |
When to use it
Ordering wood for the winter
Wood is sold by the cord and ordering short mid-season is both expensive and often impossible, since seasoned wood sells out.
Checking a delivery
A delivery sold as a cord can be measured once stacked, and the calculation gives the volume to check against.
Planning storage
Four cords is a substantial stack, and the height figure shows quickly whether one row will do or whether the space needs rethinking.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much wood does each burn rate need?
A fixed heating season across a range of burn rates.
| Burn rate | Wood needed | In cubic feet | Stack height needed, at a 8 ft long row |
|---|---|---|---|
| 0.5 ft³/h | 2.81 full cords | 360 ft³ | 11.25 ft |
| 0.75 ft³/h | 4.22 full cords | 540 ft³ | 16.88 ft |
| 1 ft³/h | 5.63 full cords | 720 ft³ | 22.50 ft |
| 1.5 ft³/h | 8.44 full cords | 1,080 ft³ | 33.75 ft |
Questions
What is the difference between a cord and a face cord?
A full cord is 128 cubic feet, stacked 4 by 4 by 8 feet, and is a defined unit. A face cord is one row 4 feet high and 8 feet long of whatever depth the logs are, so it depends entirely on log length. At the common 16 inch length a face cord is a third of a full cord.
How much wood does a winter take?
It depends enormously on the stove, the house and the climate. Three to five full cords is a common range for a household heating primarily with wood through a cold winter, and considerably less where a stove supplements central heating.
Why does the stack height come out so tall?
Because the calculation assumes a single 8 foot row. Several cords cannot be stacked that way, so the figure should be read as an indication of how many normal-height rows are needed rather than a literal stack.
Does wood type matter?
Substantially. Dense hardwoods such as oak and hickory hold roughly twice the energy per cord of softwoods such as pine, so a cord of hardwood heats far longer. The burn rate input can absorb this, but it means a cord is not a fixed amount of heat.
For heating costs from electricity instead, see the electricity bill calculator. For hot water costs, see the shower cost calculator.