Wood Pellet Stove Annual Fuel Cost Calculator

Wood pellets deliver about 8,000 BTU per pound, or about 320,000 BTU per 40-pound bag.
Pellet stoves typically run 75-85% efficient, so the heat that actually reaches the room is closer to 6,400 BTU per pound, or 256,000 BTU per bag at 80%.
That efficiency step is the one most pellet-cost estimates skip, and skipping it under-counts your bags by a fifth.

The math:

heat_needed = BTU_per_hour × hours_per_day × days_per_season bags_per_season = heat_needed / (320,000 × stove_efficiency) annual_cost = bags × price_per_bag

A worked example.
Standard 40,000 BTU/h pellet stove, 12 hours/day, 150-day heating season, 80% efficient.
Heat delivered: 40,000 × 12 × 150 = 72 million BTU.
Fuel needed: 72M / (320,000 × 0.80) = 281.25, so 282 bags, which is 5.6 tons.
At $7/bag (a rough 2026 retail figure, and it varies a lot by region and by how early you buy): $1,969 for the season.
A bulk ton bought ahead of season often runs $260-320, which is $5.20-$6.40 per bag, so the same 5.6 tons could be $1,460-1,790 if bought right. Buying pellets in February for the following winter is the single biggest saving available here.

Note what the stove’s BTU rating means. A stove advertised at 40,000 BTU/h is quoting heat output, so that is the figure to enter above. If your manual gives a BTU input rating instead, it is describing the fuel going in rather than the heat coming out, and you should multiply it by the efficiency before entering it.

Pellet stoves rarely run at full output continuously.
Most are sized for the room they heat and modulate down to 25-50% output most of the time.
A more realistic burn rate for whole-day operation is about 2-3 lb/hour for a residential stove, which works out to 0.7-1.0 bags per day.
For a 5-month heating season at 1 bag/day, that is 150 bags = 3 tons = $1,050 at $7/bag.

Comparison to other fuels, per million BTU actually delivered into the room

Every figure below charges each fuel its own efficiency, which is the only way the comparison means anything:

Read that honestly and pellets come out mid-table, not top. They beat oil, propane and electric resistance comfortably. They lose to natural gas and to a modern heat pump, and they lose badly to cordwood if you can buy hardwood at $200 a cord or cut your own.

What pellets actually buy you is independence from a gas line, a price that moves far less than oil, and a fuel you can carry in through a normal door in bags one person can lift. The cost is the labor of feeding the stove daily and stacking a few tons of bags every autumn.

A few practical points.
Premium hardwood pellets burn cleaner and produce less ash than standard softwood pellets, but cost 15-25% more.
For a normal-use stove, the difference is mostly aesthetic; ash cleanout once a week is fine either way.
Pellet quality varies more than people expect, so buy from a single mill if you can, since switching brands mid-winter often means re-tuning the stove’s air mix.
And storage is real: 4 tons of pellets needs about 200 cubic feet of dry storage (a typical garage corner), kept off the floor on pallets to prevent moisture damage.

The hidden cost most calculators skip.
A pellet stove uses 100-200 W of electricity continuously to run the auger and exhaust fan.
That is 0.1-0.2 kWh per hour, or about $30-50 per heating season at typical electric rates, small but not zero.
And during a power outage, a standard pellet stove stops working entirely (unlike a wood stove, which keeps burning).
Battery backup or a generator is needed for outage-resilient pellet heat.