Firewood Calculator

Measure a delivered stack in cords, check what a face cord really is, and see how many cords a winter needs: a firewood calculator for buyers and burners.

By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.

Quick answer: To measure delivered firewood, multiply the stack length, height and depth in feet, then divide by 128, because a cord is exactly 128 cubic feet stacked. A 16 ft by 4 ft stack of 16 in wood is 85.3 cubic feet, which is 0.67 cords, or two face cords.

Your measurements

A rectangular volume: length times width times depth.

Stack lengthftMeasure the stack where it sits, before anyone throws it into a pile. A tape across the ends of the rows is the only evidence a shortage claim can use.Stack heightftAverage height, not the tallest point. Take three readings along the row and use the middle one if the top is uneven.Stack depth, the length of the piecesinThe cut length of the wood, which is the depth of a single row. 16 in is the usual stove length, and it is what most sellers mean by a rick or face cord.Number of rows or stacks this sizeUse this when the delivery is stacked as several rows of the same size, or when two rows sit back to back.SpeciesHeat per cord tracks density, because all wood releases about 7,000 BTU per pound at 20 percent moisture. A cord of white pine carries roughly half the heat of a cord of white oak.What you paid for this wood ($)$Enter the delivered price including any stacking fee. Leave it at 0 if you cut your own. The result converts it to a price per full cord, which is the only figure two sellers can be compared on.Heat you need from wood per winter (million BTU)A supplemental stove in one room is 20 to 40. Whole-house heating in a mixed climate is 50 to 80, and a cold zone or a leaky older house runs 80 to 120.Appliance efficiency%An EPA certified stove is 70 to 80 percent, a pre-1990 stove about 50, a fireplace insert 60 to 70, and an open masonry fireplace 10 or less because the draft pulls heated room air up the flue.

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Results

Full cords: 0.67 cords; 85.3 cu ft of stacked wood, and a cord is exactly 128 cu ft. A seller has to quote you in cords or a decimal part of a cord
Stack volume: 85.3 cu ft; 16 ft long by 4 ft high by 16 in deep. Wood and the air between it both count, which is why a tight stack is worth more than a loose one
Face cords or ricks: 2 at this depth; Warning: a face cord is not a defined unit. At 16 in deep each one is 0.33 of a cord, so the same word means different wood at 12 in, 16 in and 24 in
Price per full cord: Enter what you paid; Enter the delivered price above and this becomes the price per cord, which is the only way to compare two quotes
Cords needed this winter: 3.48 cords; 60 million BTU from red oak at 70% efficiency, which delivers 17.2 million BTU per cord
What this stack covers: 19% of the season; About 11.5 million BTU of useful heat. Buy the rest by early summer so it has a season to dry below 20 percent moisture

Firewood formula

Stack volume (cu ft) = Length (ft) x Height (ft) x Depth (ft) x number of rows
Full cords = Stack volume / 128   (a cord is exactly 128 cu ft of stacked wood and air)
Face cords at this depth = Stack volume / (32 x Depth in ft)   (a 16 in face cord is 1/3 of a cord)
Cords per winter = Heat needed (million BTU) / (species million BTU per cord x appliance efficiency)

Worked example

A delivery stacked as two rows, each 10 ft long, 5 ft high and 18 in deep, sold as sugar maple for $600. Each row is 10 x 5 x 1.5 = 75 cubic feet, so the delivery is 150 cubic feet. Divided by 128 that is 1.17 cords. At 18 in deep a face cord is 48 cubic feet, so the same pile is 3.13 face cords, and each face cord is 0.38 of a cord.

The price works out to 600 / 1.17 = $512 per cord. Sugar maple carries 24 million BTU per cord, and a stove at 75 percent efficiency delivers 18 million of it. A house needing 45 million BTU from wood takes 45 / 18 = 2.5 cords for the season, so this delivery covers about 47 percent of the winter.

Quick reference

Stack volume, full cords and face cords by stack size
Stack size	Cubic feet	Full cords	Face cords
8 ft x 4 ft x 16 in	42.7 cu ft	0.33	1.00
8 ft x 4 ft x 24 in	64.0 cu ft	0.50	1.00
8 ft x 4 ft x 48 in	128.0 cu ft	1.00	1.00
16 ft x 4 ft x 16 in	85.3 cu ft	0.67	2.00
16 ft x 4 ft x 24 in	128.0 cu ft	1.00	2.00
20 ft x 5 ft x 18 in	150.0 cu ft	1.17	3.13
24 ft x 4 ft x 16 in	128.0 cu ft	1.00	3.00
32 ft x 4 ft x 16 in	170.7 cu ft	1.33	4.00

Cords, face cords and what a rick actually is

A cord is a fixed measure: 128 cubic feet of stacked wood, the volume of a pile 4 feet high, 4 feet deep and 8 feet long. Multiply the length, height and depth of the stack in feet and divide by 128. The measurement counts the wood and the air between the pieces, which is why a neat, tightly stacked row is worth more than the same cord thrown loosely together.

A face cord, rick or run is one row 4 feet high and 8 feet long, at whatever length the wood was cut. That last part is where the money goes missing. A 16 inch face cord is a third of a cord, a 12 inch one is a quarter, and a 24 inch one is half. A seller quoting $150 a rick is quoting $450 a cord if the wood is 16 inches and $300 a cord if it is 24. NIST Handbook 130 requires firewood to be advertised, sold and invoiced by the cord or a decimal fraction of a cord. Most states adopt it through their weights and measures law. Ask for the ticket in cords, and measure the stack before the seller leaves.

Species, seasoning and how much a winter takes

All wood gives off roughly 7,000 BTU per pound at 20 percent moisture, so heat per cord simply follows density. White oak is about 29.1 million BTU per cord, shagbark hickory 27.7, red oak 24.6, sugar maple 24.0, paper birch 20.3, soft maple 19.0 and white pine 15.0. Multiply by the appliance efficiency to get useful heat. An EPA certified stove is 70 to 80 percent and an older stove near 50. An open masonry fireplace is 10 percent or less, because the draft carries heated room air up the flue.

Seasoning is what separates a good cord from a bad one. Split it, stack it off the ground in single rows with the top covered and both sides open, and give it a full season. Oak wants two. Under 20 percent moisture is the target, and a $25 pin moisture meter read on a freshly split face settles the argument. Wet wood does not just burn poorly; the water absorbs heat that should reach the room and the cooled smoke condenses in the flue as creosote. Buy next winter's wood this spring, and keep the stack away from the house so the pile is not a route for carpenter ants and termites.

What this calculator leaves out

The result is volume and heat, not the rest of the job. Delivery and stacking fees are not in it, and they typically run $50 to $150 on top of the wood. Nor is a moisture meter, a tarp or shed, racks or pallets, or splitting if the wood arrives in rounds. It does not model how the season splits between mild and cold weeks, so a colder winter than planned burns more than the number here. It also leaves out chimney sweeping, which most stove makers and insurers want annually. The stove and hearth clearances in IRC Chapter 10 and any local burn ban or wood stove change-out rule sit outside it too. Firewood heat values assume 20 percent moisture, and green wood delivers far less.

Code limits that apply

NIST Handbook 130checked
Firewood is sold by the cord or a decimal fraction of a cord, not by rick or face cord
If you miss it: A rick sold at a cord price delivers a third of the wood, and the buyer has no defined quantity to dispute
NIST HB 130 sale ticket
A written invoice stating the quantity in cords and the price per cord at delivery
If you miss it: Without a ticket naming cords, a shortage complaint to state weights and measures has nothing to rest on
State firewood quarantine
Untreated firewood may not cross federal or state pest quarantine lines
If you miss it: Moving wood out of a quarantine area carries a fine and can seed emerald ash borer in a clean county
USDA heat treatment
Firewood certified heat treated to 60 C at the core for 60 minutes may cross quarantine lines
If you miss it: Uncertified wood is turned away at a park gate or inspection station and the trip is wasted

Provision	Limit	If you miss it
NIST Handbook 130checked	Firewood is sold by the cord or a decimal fraction of a cord, not by rick or face cord	A rick sold at a cord price delivers a third of the wood, and the buyer has no defined quantity to dispute
NIST HB 130 sale ticket	A written invoice stating the quantity in cords and the price per cord at delivery	Without a ticket naming cords, a shortage complaint to state weights and measures has nothing to rest on
State firewood quarantine	Untreated firewood may not cross federal or state pest quarantine lines	Moving wood out of a quarantine area carries a fine and can seed emerald ash borer in a clean county
USDA heat treatment	Firewood certified heat treated to 60 C at the core for 60 minutes may cross quarantine lines	Uncertified wood is turned away at a park gate or inspection station and the trip is wasted

Rows marked checked produce a warning in the results when an entry crosses the limit. The others are on the plans or on site and this calculator does not test them. Local amendments can be stricter; the adopted edition and the inspector govern.

Mistakes that cost money

Buying a truckload, a rick or a face cord with no dimensions given. Only the cord is defined, so measure the stack before it is dumped.
Paying oak money for aspen, cottonwood or soft maple. At 14 to 19 million BTU a cord, that is a third less heat for the same price.
Letting the driver dump and leave. Stack it and measure it the same day, because a thrown pile cannot be measured against the invoice.
Burning wood over 20 percent moisture. The heat goes into boiling water off, and the unburned smoke glazes the flue with creosote.
Hauling your own wood to a campground across a county or state line. Quarantines for emerald ash borer and spotted lanternfly cover untreated firewood.
Stacking against the house or on bare dirt. Keep rows off the ground, out from the wall, with the top covered and both sides open to wind.

Key facts

A cord is exactly 128 cubic feet of stacked wood, the volume of a pile 4 ft high, 4 ft deep and 8 ft long.
A face cord or rick cut 16 in deep is one third of a cord, because a full cord is measured to a depth of 4 ft.
Seasoned red oak holds about 24.6 million BTU per cord and white pine about 15 million, so a cord of pine carries roughly 60 percent of the heat.
Wood releases about 7,000 BTU per pound at 20 percent moisture whatever the species, so heat per cord follows the density of the wood.
NIST Handbook 130 is the national method of sale standard for firewood, and states that adopt it require sale by the cord or a decimal fraction of a cord.

Frequently asked questions

How many face cords are in a cord?

Three, if the wood is cut 16 inches long, which is the usual stove length. At 12 inches it takes four face cords to make a cord and at 24 inches only two. A face cord is not a defined unit, so always ask for the cut length.

How much firewood do I need for a winter?

Divide the heat you need by the species value times the appliance efficiency. A house needing 60 million BTU from red oak at 24.6 million per cord, burned in a 70 percent stove, takes about 3.5 cords. A supplemental stove in one room is usually 1 to 2 cords.

How can I tell if firewood is seasoned?

Split a piece and read the fresh face with a pin moisture meter; under 20 percent is ready. Seasoned wood is lighter, checked on the ends, grey rather than green under the bark, and two pieces knock together with a sharp sound rather than a dull one.

Can I take my own firewood camping?

Usually not far. Federal and state quarantines for emerald ash borer, spotted lanternfly and other pests restrict moving untreated firewood. Many parks only allow wood bought locally, or wood certified heat treated to 60 C at the core for 60 minutes. Check the state agriculture department before loading the truck.

Sources and references

Choosing Firewood: heat value by species and the cord definition (South Dakota State University Extension)
Wood for Fuel: heat value, weight per cord and seasoning (Iowa State University Extension)
NIST Handbook 130, Uniform Regulation for the Method of Sale of Commodities (NIST)
Firewood movement and quarantine requirements (Pennsylvania Department of Agriculture)

Next steps for this project

The usual order for a insulation & hvac project. See all insulation & hvac calculators.

Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.