How long a bag of pellets actually lasts

Most answers to "how long does a 40 lb bag of pellets last" are a single line: plan on 1 to 2 lb an hour, so you get 20 to 40 hours. Some of those pages are not even about grills. They are about pellet stoves, which run a different appliance on a different duty cycle. The arithmetic is fine. The inputs are missing.

Bag hours are just bag weight divided by burn rate. The whole question is which burn rate. PelletDeck's calculator builds that number from a per-model assumption at 225 F, then scales it by set point and an ambient setting. Change any of those and the bag gets longer or shorter without you touching the meat.

Same bag, same 225 F, two different answers

Start with the generic seed of 0.85 lb/hr at 225 F, which is what the calculator uses when your model is not in the list. Mild weather is 1.0x. Winter and sub-freezing is 2.1x.

• Mild, 225 F, 0.85 lb/hr: a 40 lb bag is about 47 hours of fire. A 20 lb bag is about 23 hours. Open a 12 lb brisket at 225 F in mild weather. That cook wants about 14.4 lb, so one bag covers it almost three times over.
• Winter, 225 F, 1.78 lb/hr: the same 40 lb bag is about 22 hours. The 20 lb bag is about 11 hours. Same 12 lb brisket with the winter toggle wants about 29.8 lb. One bag, one cook, and you are shopping again.

Nothing changed except the weather setting. If a chart tells you a bag lasts a fixed number of hours, it is quietly assuming a mild afternoon. Cold-weather burn covers why the controller cannot see that extra work.

Your model moves the number before you cook anything

The grill database stores a listed hopper size and an assumed burn at 225 F for each model. Those burns are labeled assumptions, not lab results. Divide 40 lb by them and mild-weather bag hours land like this:

• Traeger Ranger, 0.55 lb/hr assumed: about 73 hours. Small grill, small fire.
• Recteq RT-700, 0.80 lb/hr: about 50 hours. Legacy name, still the hopper people cite.
• Traeger Pro 575, 0.90 lb/hr: about 44 hours.
• Traeger Pro 780, 1.05 lb/hr: about 38 hours. More steel, same 18 lb hopper.
• Traeger Timberline XL, 1.15 lb/hr: about 35 hours.

Run the same packer on two of those and the bag looks like a different product. A 12 lb brisket at 225 F on a Pro 575 is about 15.2 lb. The same packer on an RT-700 is about 13.6 lb. That is two and a half of those cooks per bag on the Traeger and almost three on the Recteq, for the same meat on the same dial.

High heat eats the bag faster than the clock suggests

Burn rate scales by (target temp / 225)^1.2, so a hot cook is not a free short cook. The hours drop, the pounds per hour rise faster, and the bag drains at a rate that has nothing to do with your 225 F expectations.

• A 5 lb chicken at 350 F on the generic seed: about 1.44 lb/hr, so the 40 lb bag is about 28 hours of fire. The cook itself is only about 3.3 lb, because it is over in about two hours.
• Wings at 450 F on a Pro 575: about 2.07 lb/hr. That bag is now about 19 hours. A full 18 lb hopper runs about 8 hours 32 minutes at that rate.

So a bag full of short hot cooks lasts many cooks and few hours. A bag full of overnight briskets lasts few cooks and many hours. Both are true at once, which is why the hours-only answer feels wrong to everybody.

The hopper is the number that wakes you up

Bag duration is a shopping question. Hopper duration is a sleep question. The calculator reports both: how many pounds the cook wants, and how many hours a full hopper runs at that burn rate.

• 18 lb hopper, 0.85 lb/hr mild: about 20 hours 46 minutes of fire.
• Same hopper in winter at 1.78 lb/hr: about 9 hours 53 minutes.

A 40 lb bag in the garage does not help at 3 a.m. if the hopper holds 18 lb and the cook needs 30. That is the whole point of empty hopper overnight. If you want to shop by that number instead of guessing, the grill database can filter on it: models whose listed hopper and assumed burn cover 24 or more hours at 225 F, or just the 30 lb and larger hoppers.

How long pellets last in storage is a different question

Pellets are compressed sawdust held together by the wood's own lignin. Dry, in a sealed bag, in a place that does not swing damp, they keep a long time. There is no meaningful expiration date. Humidity is the clock, not the calendar.

Damp pellets swell, crumble back toward sawdust, and jam augers. If a handful breaks apart or feels soft, that bag is fuel you cannot plan with. Do not soak wood pellets covers why adding water on purpose is worse than the rain that did it by accident.

The dust at the bottom of a bag burns faster and less predictably than whole pellets. It is not a scandal. It is just not the fuel the burn assumption describes.

What this page will not do

It will not tell you a bag lasts N hours on your patio. Wind, a leaky gasket, a dirty fire pot, and lid peeking are all outside the formula, and they push burn up rather than down. The exact exponents are on the methodology page.

If your question is really "how many pounds does this cook need," start with how many pounds of pellets instead. That page does the per-cook math. This one does the bag. And none of these hours are a doneness signal. Use a probe and read the food-safety disclaimer.