What is a full cord of firewood?

A full cord is a stack measuring exactly 4 feet tall by 4 feet deep by 8 feet long — 128 cubic feet of stacked wood. Because logs are round and irregular, only about 80-90 cubic feet of that is actual solid wood; the rest is air between the pieces. The full cord is the legal standard unit of firewood measurement in the United States and Canada.

What is a face cord and how does it differ from a full cord?

A face cord (also called a rick) is 4 feet tall and 8 feet long — the same face dimensions as a full cord — but only as deep as the log length cut, typically 16 inches. At 16 inches deep a face cord is exactly one-third of a full cord. If your logs are cut to 12 inches a face cord is only one-quarter of a full cord, so always confirm the log length when buying by the rick.

How is the stacked volume converted to full cords?

The formula is straightforward: multiply height (ft) × length (ft) × log depth (ft) to get stacked cubic feet, then divide by 128. So a stack 4 ft tall × 8 ft long × 1.33 ft deep (16 in logs) gives exactly 42.7 ft³ / 128 = 0.33 full cords — one face cord.

How do I estimate how many cords I need for a heating season?

The key variables are your home's seasonal heat demand in BTU, the species you are burning, and your appliance efficiency. A well-insulated 1,500 sq ft home in a cold climate might need 50-80 million BTU per season. Divide your seasonal demand by the usable BTU per cord (species BTU × efficiency) to get the cord count. The calculator does this automatically when you enter your seasonal demand.

Which wood species gives the most heat per cord?

Hickory tops the list at around 27.7 million BTU per cord of air-dried wood, followed closely by white oak at 26.5 million and hard maple at 25.5 million. Softwoods like white pine (~17.1 million BTU) and eastern red cedar (~18.2 million BTU) burn hotter initially but produce less total heat and more creosote. For home heating, dense hardwoods are almost always the better long-term value even when priced higher per cord.

What appliance efficiency should I use?

A modern EPA-certified wood stove is 70-80% efficient; use 75% as a safe estimate. An older non-certified stove runs 50-65%. An open masonry fireplace is notoriously inefficient at just 10-20%, and can actually pull more warm air out of the room than the fire produces. Fireplace inserts with glass doors and a blower recover to around 65%. Use 75% for a good stove, 15% for an open fireplace.

Is my firewood data saved or uploaded?

No. Every calculation happens entirely in your browser. No numbers are sent to any server and nothing is stored after you close the tab.

Firewood Cord Calculator

A firewood cord calculator that converts your stack dimensions into full cords, face cords, solid cubic feet and a total dollar value — then layers on BTU heat output by wood species and an appliance-efficiency-adjusted seasonal planner so you know exactly how much wood to buy before the first cold snap. Whether you are pricing a delivery, measuring a pile already in your yard, or planning next winter’s supply, this tool gives you every number in one place without any maths on your part.

How it works

The fundamental unit is the full cord: a stack 4 ft × 4 ft × 8 ft = 128 cubic feet of stacked wood. Every other measurement flows from that reference.

Full cords = (height ft × length ft × depth ft × number of stacks) / 128

Log depth is entered in inches and converted to feet internally. A 16-inch log gives a depth of 1.333 ft; a stack 4 ft × 8 ft × 1.333 ft holds 42.67 ft³ — exactly one-third of a full cord (one face cord).

Solid wood content applies a packing factor of 0.65: round, split logs typically fill about 65% of the stacked space with actual wood fibre; the rest is air. That gives you the true solid-wood volume, which drives BTU calculations.

BTU heat output is calculated as:

Usable BTU = Full cords × BTU per cord (species) × (efficiency / 100)

BTU-per-cord figures are for air-dried wood at roughly 20% moisture content — the standard for seasoned firewood. Green wood can have 30-50% more moisture, which steals a significant portion of the heat energy converting water to steam; always season wood at least 6-12 months before burning.

Seasonal planning inverts the formula. Given your estimated seasonal heat demand in million BTU:

Cords needed = Seasonal demand (BTU) / (BTU per cord × efficiency)

The calculator then multiplies by your price per cord to give the total cost to buy.

Worked example

You have three stacks each 4 ft tall × 8 ft long × 16 in deep, split White Oak, at $350 per cord. Your home needs an estimated 60 million BTU per season and you heat with a certified wood stove at 75% efficiency.

Stacked volume: 4 × 8 × 1.333 × 3 = 128 ft³
Full cords: 128 / 128 = 1.00 cord
Face cords: 128 / (4 × 8 × 1.333) = 3.00 face cords
Solid wood: 128 × 0.65 = 83.2 ft³
Stack value: 1.00 × $350 = $350
Gross BTU: 1.00 × 26,500,000 = 26.5 million BTU
Usable BTU: 26,500,000 × 0.75 = 19.9 million BTU
Cords needed for 60M BTU: 60,000,000 / (26,500,000 × 0.75) = 3.02 cords
Estimated season cost: 3.02 × $350 = $1,057

So your three-stack pile covers roughly one-third of your winter — you would need to order two more cords to reach your seasonal demand.

Species	BTU/cord (M)	Cords for 60M BTU at 75% eff.
Hickory	27.7	2.89
White Oak	26.5	3.02
Hard Maple	25.5	3.14
White Ash	23.6	3.39
Birch	20.3	3.94
White Pine	17.1	4.68

Denser species require fewer cords for the same heat output; if hickory costs only 10% more than pine per cord but delivers 62% more usable heat, it is the far better value per BTU.

Formula note

The packing factor of 0.65 is a commonly cited industry average for stacked, split firewood. Tightly stacked small splits can reach 0.70-0.75; loosely thrown rounds may fall to 0.60 or below. The formula for solid-wood volume is:

Solid ft³ = (H × L × D) × 0.65

The BTU figures in this calculator assume air-dried hardwood at approximately 20% moisture content (MC). At 50% MC (green wood), effective BTU output can be 30-40% lower because a large fraction of combustion energy is consumed evaporating moisture. A moisture meter is the only reliable way to confirm your wood is actually ready to burn.