Firewood Calculator

What Is a Firewood Calculator?

A firewood calculator estimates the number of cords or face cords of firewood needed to heat your home through a season based on your location, home size, and heating method. It helps you order the right quantity and budget for heating costs.

How Much Firewood Do You Need?

The amount of firewood you need depends on how you use it. A home heated primarily by wood in a cold climate uses 4–8 cords per season. A supplemental fireplace used on weekends might use 0.5–1.5 cords. A cord is the standard firewood measurement: a neatly stacked pile 4 feet wide × 4 feet tall × 8 feet long = 128 cubic feet.

Firewood Measurements

Full cord: 4′ × 4′ × 8′ = 128 cu ft. The legal measurement for firewood sales. Face cord (rick): 4′ × 8′ × one log length (typically 16″). About 1/3 of a full cord. Pickup truck load: A standard 8-foot bed loosely stacked holds roughly 1/3–1/2 cord. A heaped short bed holds about 1/4 cord. Always buy by the cord, not by the "truckload" — it's the only standardized measurement.

Factors That Affect Consumption

Heating method: EPA-certified wood stoves are 70–80% efficient. Open fireplaces are only 10–20% efficient — most heat goes up the chimney. Fireplace inserts are 60–80% efficient. Home size and insulation: A well-insulated 1,500 sq ft home might need 3 cords; a poorly insulated 2,500 sq ft home might need 8+. Climate zone: Mild winters (Zone 1) need 50% less than severe winters (Zone 3). Wood species: Dense hardwoods (oak, hickory, maple) produce more BTUs per cord than softwoods (pine, spruce).

BTU Output by Wood Species

High BTU (20–28 million per cord): Osage orange, hickory, white oak, sugar maple, beech. Medium BTU (16–20 million): Red oak, birch, cherry, ash, elm. Low BTU (12–16 million): Pine, spruce, poplar, willow, basswood. One cord of oak provides roughly the same heat as 150–175 gallons of heating oil or 200–225 therms of natural gas.

Seasoning and Storage

Freshly cut (green) wood contains 40–50% moisture and burns poorly — producing less heat, more smoke, and more creosote buildup. Season wood for 6–12 months before burning, split and stacked off the ground with air circulation. Properly seasoned wood has <20% moisture content. Cover the top of stacked wood but leave sides open for air flow. Store at least 30 feet from your home to reduce fire risk and pest issues.

Cost Comparison

Firewood costs $150–400 per cord depending on species and region. At 5 cords per season, that's $750–2,000 for winter heating — often cheaper than oil ($2,500–4,000) or propane ($2,000–3,500) for the same heating output. However, wood requires significant labor (splitting, stacking, loading, ash cleanup) and infrastructure (stove, chimney, storage area).

Firewood Volume and Heating Value

Firewood Measurement, Selection, and Storage

Firewood is measured in cords — a stack measuring 4 feet wide × 4 feet high × 8 feet long, totaling 128 cubic feet. However, because logs are round and do not pack perfectly, the actual solid wood in a cord is approximately 80–90 cubic feet, with the remainder being air space. A face cord (or rick) is a common retail unit: 4 feet high × 8 feet long × one log length deep (typically 16 inches), equaling one-third of a full cord. Always clarify the unit when purchasing — "a cord" means different things to different sellers, and price comparisons require consistent units.

BTU Output by Wood Species

The energy content of firewood varies enormously by species. Hardwoods produce significantly more heat per volume than softwoods because they are denser. High-BTU hardwoods (20–30 million BTU per cord): Osage orange (32.9M), hickory (27.7M), white oak (25.7M), sugar maple (24M), red oak (24M), and ash (23.6M). Medium-BTU hardwoods (15–20M): birch (20.3M), cherry (20M), elm (19.5M), and walnut (20M). Softwoods (10–17M): Douglas fir (17.4M), pine (15–17M), spruce (15.5M), and cedar (12.2M). For heating efficiency, dense hardwoods deliver more heat per dollar because you burn less volume for the same warmth. Softwoods ignite more easily and make excellent kindling but burn faster and produce more creosote.

Seasoning and Moisture Content

Freshly cut (green) wood contains 40–60% moisture by weight. Burning green wood wastes up to half the potential energy evaporating that moisture, produces excessive smoke, accelerates creosote buildup in chimneys (creating fire hazard), and generates substantially more air pollutants. Properly seasoned firewood has a moisture content below 20% — achieved by splitting wood and stacking it off the ground in a sunny, well-ventilated location for 6–12 months depending on species, climate, and piece size. Dense hardwoods like oak may require 12–18 months. A moisture meter ($15–$30) inserted into a freshly split face provides an objective reading. Signs of seasoned wood include lighter weight, visible end-grain cracks (checking), a hollow sound when pieces are knocked together, and bark that pulls away easily.

How Much Do You Need?

A home heated primarily with wood in a cold climate (northern U.S.) typically burns 3–6 cords per season. A home using wood as supplemental heating burns 1–2 cords. A recreational fireplace (weekly use, November–March) uses roughly 0.5–1 cord. These estimates vary based on home insulation quality, stove efficiency, local winter severity, and desired indoor temperature. A modern EPA-certified wood stove operates at 70–80% efficiency, producing far more usable heat per cord than an open fireplace (10–20% efficiency) or older stove (30–50%).

Storage Best Practices

Proper storage accelerates seasoning and prevents decay. Stack wood off the ground on pallets, rails, or a firewood rack to prevent moisture wicking from soil. Leave 3–6 inches of airflow space between stacks and any building wall to allow air circulation and discourage pest colonization. Cover the top only with a tarp, metal roof, or purpose-built cover — leaving the sides exposed to airflow. Fully tarped stacks trap moisture and promote mold growth. Stack pieces bark-side up when possible, as bark acts as a natural rain shield. Place your woodpile at least 20–30 feet from your house to reduce the risk of termites, carpenter ants, and other wood-boring insects migrating to your home's structure. Never store firewood indoors except for a day or two of supply — indoor storage introduces insects and can harbor mold spores.

Buying Tips

Purchase firewood in spring or early summer for next winter's use — prices are 20–30% lower during off-season, and you gain additional seasoning time. Verify the seller's unit of measurement and inspect the wood for green vs. seasoned quality before accepting delivery. Reputable sellers will specify species, cut date, and moisture content. Avoid wood from unknown sources that may carry invasive insects like the emerald ash borer — many states restrict firewood transport across county or state lines. Local firewood, bought and burned within 50 miles of its origin, protects forest health while supporting your heating needs.

Chimney Maintenance

Burning any wood produces creosote — a flammable tar-like residue that accumulates on chimney walls. Have your chimney inspected and cleaned by a certified chimney sweep at least once per year or after every cord burned, whichever comes first. Creosote buildup of just 1/8 inch is sufficient to fuel a chimney fire, which can reach temperatures above 2,000°F and spread to the house structure. Burning only well-seasoned hardwood, maintaining hot fires (rather than smoldering), and ensuring adequate combustion air all minimize creosote accumulation between cleanings.

See also: Energy Savings · Electricity Cost · Cubic Feet Calculator · Carbon Footprint · Generator Size