Propane
How long will a propane tank last?
June 4, 2026
If propane heats your house, a 500-gallon tank gets you through about 2 to 4 months of winter — and the cold decides which end.
That range is wide on purpose. The space between the tidy average and the week it actually turns cold is exactly where people run out, so it's worth a minute.
A "full" tank isn't full
Propane only fills to about 80% — that empty fifth gives the liquid room to expand when it warms up. So the number stamped on the tank is bigger than what you can actually burn:
| Tank | Usable propane (~80% full) |
|---|---|
| 100 lb cylinder | ~23 gallons |
| 250-gallon | ~200 gallons |
| 500-gallon | ~400 gallons |
| 1,000-gallon | ~800 gallons |
And the gauge reads a percentage, not gallons. A 500-gallon tank sitting at 40% has about 200 gallons in it — 0.40 × 500 — not 40. (A "full" tank reads around 80%, which throws everyone the first time.)
What actually drains it
Here's where the table stops helping, because your burn rate comes down to two things: what runs on propane in your house, and how cold it gets.
- Heat is the big one. A furnace burns 2 to 3 gallons a day in a normal winter week, and twice that in a cold snap. If propane heats your home, this is basically your whole story.
- Water heater: about a gallon a day.
- Just a stove? You're barely sipping — a few gallons a month. A 500-gallon tank could last you years.
- Standby generator: 2 to 3 gallons an hour under load, so one long outage throws every number here out the window.
For a house that heats with propane, it shakes out roughly like this:
| Tank (usable) | Normal winter (~2.5 gal/day) | Cold snap (~5 gal/day) |
|---|---|---|
| 250-gal (200) | ~2.5 months | ~6 weeks |
| 500-gal (400) | ~5 months | ~2.5 months |
| 1,000-gal (800) | ~10 months | ~5 months |
Stove-and-water-heater only? Multiply those by a lot.
Why the average lies to you
The trap is treating "2.5 gallons a day" like a fact. It's not — it's an average, and propane heat doesn't burn on average. It burns on weather.
A week that runs 15 degrees colder than normal doesn't nudge your usage up. It can double it. The neat daily number hides those cold weeks completely — and the cold weeks are exactly when you don't want to be scraping the bottom of the tank. Plan around the average, catch a brutal stretch in January, and you come up empty.
So how long will your tank last?
Two honest ways to find out:
- Run your actual numbers. The Propane Refill Date Calculator takes your tank size, gauge reading, and usage and hands you a real date instead of "a few months." Got one specific tank? The 500-Gallon Propane Tank Calculator turns your gauge percentage straight into gallons and days left.
- Or stop doing the math. Log a reading now and then and let it track your real burn rate against your local weather — so you hear about a refill before a cold snap makes the call for you.
Quick answers
How long does a 100 lb propane tank last? Months for a stove — it barely sips. A week or two for a space heater you're leaning on. Those cylinders are built for appliances and backup heat, not warming a whole house.
How long does a 500-gallon tank last in winter? If it's heating the house, 2 to 4 months between fills, depending on the cold and how well the place holds heat. Figure ~400 usable gallons against a furnace eating 2 to 3 a day — more when it's brutal out.
How do I know how many gallons are left? Read the dial on top, then multiply by the tank size. A 500-gallon tank at 30% is holding about 150 gallons. (It only fills to ~80%, so "full" sits near 80%.)
Why did my tank run out early? A cold snap, almost every time. Propane heat rides the temperature, so a hard freeze quietly doubles your burn — same house, same habits, just colder air. A once-a-month look won't catch that. When the cold really digs in, check the tank more often than feels necessary; that's exactly the week it empties faster than anyone expects.