Propane Tanks & Cylinders: Sizes, Refills & Runtime
Last verified: September 2026
Everything you actually need to know, in plain English — no jargon, no rabbit holes. If you'd rather have someone help in person, my number is (330) 200-8042.
Propane Tanks & Cylinders: Sizes, Refills & Runtime
Two questions come up more than almost any other: what size propane tank or cylinder should I have, and how long will it actually run my generator? The honest answer to the second one is it depends — but that's not a dodge, it's the whole useful idea once you understand it. This guide walks through the common tank sizes, the refill-versus-exchange choice, and the simple relationship between tank size, your load, and how long you can expect to run.
Common Questions
1 What sizes of propane tanks and cylinders do people actually use for a generator?
Most households use one of three general sizes: 20-lb cylinders (the familiar grill-tank size), larger 100-lb cylinders, or a big yard tank installed on the property. Which one fits you depends on how often and how long you expect to run.
2 Should I refill my cylinder or just exchange it?
Both are fine. Exchanging swaps your empty for a filled one at a store or cage — fast, but you don't know that tank's history. Refilling fills the cylinder you already own at a propane supplier — you keep the tank you know. Plenty of people use whichever is convenient that day.
3 How long will a tank of propane actually run my generator?
That depends on two things together: how much fuel is in the tank, and how hard you're running the generator. A bigger tank or a lighter load both stretch runtime; a smaller tank or a heavier load both shrink it. Check your generator's manual for its approximate fuel use, and consider timing a real test run with your own typical load — that tells you far more than any generic number.
4 Do propane cylinders expire?
The propane itself doesn't go stale, but the cylinder does need periodic attention. US cylinders generally need requalification around 12 years from manufacture, and periodically after that — the date is stamped on the collar. Give every cylinder a quick yearly look for rust, dents, or a damaged valve too.
5 Is a bigger tank always better?
Bigger generally means longer runtime and steadier performance, especially in cold weather — but weigh it against storage space, what your supplier offers, and how often you'd realistically use it. For many town households, a couple of well-kept 20-lb cylinders is plenty.
6 Can you help me figure out the right setup?
Gladly — that's a great conversation to have before you buy anything. I'll help you weigh tank size against how you'll actually use your generator, and point you toward a setup that fits your home. $99 flat for an in-home visit. Call or text (330) 200-8042.
Want Me to Help With Yours?
Getting a backup generator picked, set up, and safe is one of the things I'm glad to do in person. I bring the patience and the know-how — you keep your seat. We'll get it starting, sort out the fuel and the safe hookup, walk through running your essentials, and make sure everyone knows the carbon-monoxide basics. $99 flat, and every visit is 30-day come-back-free. (330) 200-8042.
Would you rather I just do this for you?
No shame in it — plenty of folks would rather hand it off, and that's what I'm here for. I'll come to your home, set it up right, and make sure it's working before I leave. Flat $99 per visit — no jargon, no upsell, and every visit is 30-day come-back-free.
Not a hardware job? I can often fix it remotely for $49 — a secure screen-share, up to 2 hours, that you watch the whole time and can end whenever (included free for $39/mo Support Plan members, and it counts toward the $99 if it turns out I need to come out).