Firewood Calculator
The cord is a legal unit of measure, not a rule of thumb: 128 cubic feet of wood ranked and well stowed. This calculator turns the stack in front of you into cords, so you can check an offer against the only measure a seller is allowed to sell by.
How it works
Multiply the three dimensions of the stack. Length and height are what you see from the front; the third dimension is the depth of the stack, which for a single row is simply the length the logs were cut to. A 16 in cut is 1.33 ft.
Divide by 128. That figure is the definition in the model regulation the states adopt from NIST: a cord is the wood contained in 128 ft³ when it is ranked and well stowed. A 4 × 4 × 8 ft stack is exactly one cord — 4 × 4 × 8 is 128.
'Ranked and well stowed' is doing real work in that sentence. The 128 ft³ is stacked volume, with the air gaps between logs included; it is not 128 ft³ of solid wood. A pile tipped off a truck bed and never stacked cannot be measured this way at all, which is the point of the requirement.
Formula: Cords = stack length ft × stack height ft × log length ft ÷ 128 ft³
Measuring on site
- Stack the wood before you measure it, in rows straight enough that the logs touch. Measure the face — length and height — with a tape, and take the depth as the log length rather than eyeballing it.
- Measure each row separately if the rows are cut to different lengths, and add the volumes. Mixed cuts in one stack are the usual reason a measurement comes out short of what was ordered.
- Measure to the top of the stacked wood, not to the top of the tallest log. Height taken off a single high piece over-reports the whole stack.
Waste and what it covers
Firewood has no waste factor, but it does have a moisture problem the volume cannot show. Green wood shrinks as it seasons, so a stack measured wet will measure smaller in six months, and it delivers less heat per cord in the meantime. Measure on delivery if you are checking a quantity, and buy seasoned wood if you intend to burn it this winter.
| Stack face | Log length | Stacked volume | Cords |
|---|---|---|---|
| 4 × 8 ft | 12 in | 32 ft³ | 0.25 |
| 4 × 8 ft | 16 in | 42.67 ft³ | 0.333 |
| 4 × 8 ft | 24 in | 64 ft³ | 0.5 |
| 4 × 16 ft | 16 in | 85.33 ft³ | 0.667 |
| 4 × 24 ft | 16 in | 128 ft³ | 1.0 |
| 4 × 8 ft, 4 ft deep | 48 in | 128 ft³ | 1.0 |
Questions
- How much is a face cord of wood?
- It depends on the log length, which is exactly why the term is a problem. A 'face cord' usually means a 4 ft by 8 ft stack one log deep. Cut to 16 in, that is 42.67 ft³ — one third of a cord. Cut to 12 in it is a quarter of a cord, and cut to 24 in it is half. The same words describe three different quantities of wood.
- Is it legal to sell firewood by the face cord?
- In most states, no. The NIST Handbook 130 model regulation, which the majority of states adopt, states that the terms 'face cord', 'rack', 'pile' and 'truckload' shall not be used when advertising, offering for sale, or selling wood for use as fuel. Firewood is sold by the cord or fraction of a cord. A seller quoting face cords is either unaware of the rule or counting on you being unaware of it.
- What are the dimensions of a full cord of wood?
- 128 ft³ stacked, classically as a 4 ft high by 8 ft long stack, 4 ft deep. Any stack multiplying to 128 ft³ is a cord: a 4 ft high row of 16 in logs, for example, has to run 24 ft to make one.
- How do I check that I got the cord I paid for?
- Stack it and measure it. Multiply height by length by log length in feet and divide by 128. If the result is 0.7, you received 0.7 of a cord, whatever the delivery was called. Then enter what you paid: the calculator divides it by the cords you actually got, which is the figure to compare between sellers. A $250 delivery that stacks to a third of a cord cost you $751 a cord. Ask for the quantity in cords in writing before delivery, since that is the unit the sale is legally required to use.
Sources
- NIST, Office of Weights and Measures — Handbook 130, Uniform Regulation for the Method of Sale of Commodities, §2.4.1.2 and §2.4.4“Cord. – The amount of wood that is contained in a space of 128 ft3 when the wood is ranked and well stowed. ... The terms “face cord,” “rack,” “pile,” “truckload,” or terms of similar import shall not be used when advertising, offering for sale, or selling wood for use as fuel.”
Figures and sources last checked by The BuilderTally Team in August 2026.