Firewood Calculator (Cords, Volume & Cost)

Firewood Guide

Firewood Units Explained

Firewood is sold in a confusing variety of units, which makes comparing prices hard. A cord is the traditional measure (common in North America): a stacked pile measuring 4 × 4 × 8 feet, equal to 128 cubic feet or about 3.62 cubic metres of stacked wood (including the air gaps between logs). A face cord (or 'rick') is one-third of a full cord — a stack 4 feet high and 8 feet long but only one log deep, so its volume depends on the log length. In the UK, firewood is more often sold by the cubic metre, by bulk bag (typically around 0.6-0.85 m³, often quoted as 'roughly 1 cubic metre' loosely), by the load (van or trailer load — an imprecise measure), or by net/dumpy bags. Loose-thrown versus stacked: a 'loose cubic metre' of thrown logs contains less actual wood than a 'stacked cubic metre' because of larger air gaps — typically about 0.7 m³ of wood per loose m³. This is a common source of confusion and apparent overcharging. When comparing prices, always try to compare the same unit (ideally stacked cubic metres or weight of seasoned wood) and ask whether a quoted volume is loose or stacked.

Seasoned vs Wet Wood

The single most important factor in firewood quality is moisture content. Freshly cut ('green') wood can be 50%+ water by weight. Burning wet wood is inefficient and harmful: much of the heat is wasted boiling off water rather than warming your home, it produces more smoke and creosote (which builds up in chimneys and is a fire risk), and it pollutes more. Seasoned or kiln-dried wood should be below 20% moisture (ideally 15-20%). It lights easily, burns hot and clean, and produces far more usable heat per log. In the UK, the 'Ready to Burn' certification scheme indicates wood sold at 20% moisture or less — and since 2021, regulations restrict the sale of wet wood in small volumes for exactly these reasons. Seasoning: freshly cut wood typically needs 1-2 years of air-drying (split, stacked off the ground, covered on top but open at the sides for airflow) to season properly. Hardwoods take longer than softwoods. Kiln-dried wood is dried artificially and ready immediately, at a premium price. A moisture meter (cheap and widely available) lets you check wood before burning — under 20% is the target.

How Much You'll Need

Annual firewood needs vary enormously with how you burn. As a rough guide: occasional use (a fire on cold evenings, not for primary heat) might use 1-3 cubic metres a season. Regular use (most evenings through the heating season) might use 3-7 cubic metres. Primary heat source (heating the home mainly with wood) can use 7-15+ cubic metres a season, depending on home size, insulation, stove efficiency, and climate. Factors that affect consumption: stove efficiency (a modern, well-rated stove extracts far more heat per log than an open fire, which is very inefficient — much heat goes up the chimney), home insulation, how cold your winters are, and how much of your heating the wood provides. Wood species matters too: dense hardwoods (oak, ash, beech, hornbeam) burn longer and hotter per log than softwoods (pine, spruce), though softwoods light easily and are fine for kindling and quick fires. This calculator estimates how long a given volume will last at your burn rate, or how much to buy for a season — useful for budgeting and for buying in bulk (which is usually cheaper) rather than expensive small bags.

Buying and Storing

Buying smartly and storing well saves money and ensures good burning. Buying: bulk is cheaper per unit than small bags, so if you have storage, buying a larger quantity (and ideally seasoning it yourself, or buying seasoned in bulk) cuts cost. Compare prices on the same basis (stacked m³ or weight of seasoned wood). Buy 'Ready to Burn' certified or check moisture yourself. Beware vague units like 'a load' — ask for the volume. Storing: keep wood off the ground (on pallets or rails) to prevent it drawing up damp. Cover the top to keep rain off, but leave the sides open for airflow — wood needs ventilation to stay dry and to continue seasoning. Store in a sunny, breezy spot if seasoning. Bring a few days' supply indoors before burning so it's at room temperature and any surface moisture dries. Stack stably. Safety and regulations: in the UK, Smoke Control Areas restrict what you can burn and require approved ('exempt') appliances — check whether you're in one. Only burn dry, seasoned wood (never treated or painted wood, which releases toxic fumes). Sweep your chimney regularly (at least annually for regular use) to prevent dangerous creosote build-up. This calculator helps with quantities and cost; for installation and safety, follow stove manufacturer guidance and local regulations.