How Long Does a 20 lb Propane Tank Last? [Grill Time Calculator]
Doug FleischerShare
Short answer: A full 20 lb propane tank usually lasts about 18 to 22 hours on a medium-heat gas grill, or roughly 10 to 14 hours on high heat. Runtime depends on total BTU output, burner settings, weather, and how full the tank is.
Planning a weekend cookout, patio season, or weekly grilling routine starts with one practical question: how long will your propane last before you need a refill or exchange?
This guide explains how 20 lb tank runtime works, gives realistic estimates by appliance, and includes a calculator below so you can estimate hours remaining based on your setup.
How much energy is in a 20 lb propane tank?
A full 20 lb propane tank holds about 430,000 BTUs of usable energy. That is the industry-standard figure used for grill planning, though actual capacity can vary slightly depending on fill level and tank condition.
Propane burns at different rates depending on your appliance. The math is straightforward:
Estimated hours = remaining BTUs ÷ BTU used per hour
If you run a grill at 20,000 BTU per hour on medium heat, a full tank lasts about 21.5 hours of continuous use. Most people do not run burners at full output the entire time, so real-world grilling often stretches further than the math suggests.
How long does a 20 lb tank last on a gas grill?
On a typical two-burner grill at medium heat, expect about 18 to 22 hours of active grilling from a full tank. High-heat searing, wind, and cold weather can shorten that window.
| Appliance / use | Approx. BTU per hour | Hours from a full 20 lb tank |
|---|---|---|
| Gas grill — medium heat | 20,000 BTU/hr | ~18 to 22 hours |
| Gas grill — high heat | 36,000 BTU/hr | ~10 to 14 hours |
| Patio heater | 40,000 BTU/hr | ~10 to 11 hours |
| Fire pit | 50,000 BTU/hr | ~8 to 9 hours |
| Side burner / low use | 12,000 BTU/hr | ~30+ hours |
What affects propane tank runtime?
Runtime changes based on burner setting, outdoor temperature, wind, and tank fill level. These factors matter as much as the BTU rating on your grill.
- Burner setting: Low and medium settings use far less propane than all burners on high.
- Weather: Cold air and wind force appliances to work harder and burn faster.
- Preheating habits: Long preheat cycles with the lid open consume extra fuel.
- Tank level: A tank that feels "half full" may be closer to 30 to 40 percent depending on how you measure it.
- Appliance efficiency: Older grills, clogged burners, and poor ventilation reduce effective runtime.
How can you tell when a 20 lb tank is running low?
Weigh the tank, use a hot-water level test, or install an inline gauge to estimate remaining propane. A full 20 lb tank typically weighs about 37 pounds total; an empty shell weighs about 17 pounds.
If you are planning ahead rather than guessing, ordering a 20 lb propane exchange before a big event is usually easier than making an emergency run mid-cookout.
Running low? Get a full tank delivered
JackGas delivers 20 lb propane exchanges across much of northern and central New Jersey. Leave your empty tank accessible, and the driver swaps it for a filled exchange tank on your ZIP code route.
Current JackGas pricing: 20 lb propane exchange from $16.95. Need a tank to swap? Spare 20 lb tanks are $49.99.
Check whether JackGas delivers to your address with the ZIP delivery checker, browse New Jersey service areas, or read the full NJ propane delivery guide.
Frequently asked questions
How long does a 20 lb propane tank last on a grill?
On medium heat, a full 20 lb tank often lasts about 18 to 22 hours of active grilling. High-heat cooking uses propane faster — often closer to 10 to 14 hours.
How many BTUs are in a 20 lb propane tank?
A full 20 lb propane tank typically provides about 430,000 BTUs of energy, though exact capacity can vary slightly by tank and fill level.
How can I tell how much propane is left?
Common methods include weighing the tank, using a hot-water pour test along the tank side, checking an inline gauge, or estimating from recent usage.
Does JackGas deliver full 20 lb propane tanks in New Jersey?
Yes. JackGas delivers 20 lb propane exchanges across much of northern and central New Jersey. Check your ZIP code on the JackGas delivery page to confirm availability and schedule.
About JackGas: JackGas is a New Jersey propane delivery service specializing in 20 lb tank exchange for grills, patio heaters, fire pits, and outdoor kitchens. Service areas include towns across Bergen, Passaic, Essex, Hudson, Morris, and Ocean counties.
