How Long Does a Propane Tank Last?

Tank duration by size and use case — heating a home, running a generator, BBQ'ing, hot water — plus how long the tank itself lasts before it needs replacing.

Last verified 27 April 2026 · Sourced from EIA weekly residential propane price data

Whole-Home Heating: Tank Duration by Size and Climate

Tank Size	Usable	Mild climate (~600 gal/yr)	Moderate (~1,000 gal/yr)	Cold (~1,500 gal/yr)
120 gal	96 gal	~2 months	~1.2 months	~3 weeks
250 gal	200 gal	~4 months	~2.4 months	~1.6 months
500 gal	400 gal	~8 months	~4.8 months	~3.2 months
1,000 gal	800 gal	~16 months	~9.6 months	~6.4 months

Climate gallons assume 2,000 sqft home with propane furnace, water heater, and cooking range. Heating-season concentration means a typical home goes through 70-80% of annual gallons in November-March, so heating-season fills happen on 1-3 month cycles even with a large tank.

How Long Does a Tank Last for Each Appliance?

Furnace / boiler (whole-home heating)

~5-8 gallons/day in winter

Single biggest user. 500 gal tank refills 2-3 times per heating season for a typical 2,000 sqft home. Annual usage scales linearly with heated square footage.

Tankless water heater

~50-80 gallons/year

Surprisingly modest. A propane tankless unit serving a family of four uses about 1.5 gallons per day. A 250-gal tank dedicated to water heating only would last 18+ months.

Tank water heater (40-gal)

~200-300 gallons/year

Less efficient than tankless. Standby losses add up. A 500-gal tank dedicated to water heating only would last 18-24 months.

Cooking range (4-burner)

~30-50 gallons/year

Tiny consumer. A 100-lb cylinder (~24 gallons) lasts a typical kitchen 6-8 months of daily use.

Clothes dryer

~30-50 gallons/year

Comparable to a range. Five loads per week is typical.

Standby generator (20 kW)

2-4 gallons/hour during operation

500-gal tank lasts ~5-8 days of continuous run-time. For week-long outage resilience, install a dedicated generator tank or upsize your home tank.

BBQ grill (mid-size, 30k BTU/hr)

~0.27 gal/hour at full burner

20-lb BBQ tank lasts ~17-20 hours of grilling. About 18-20 backyard cooks for an average household.

Pool / spa heater

1-2 gallons/hour during operation

Pools are seasonal but heavy. A pool heater can use 500+ gallons in a swimming season. Underground pool heaters often have dedicated tanks.

Patio heater (40k BTU/hr)

~0.4 gal/hour at full burner

20-lb tank lasts about 11-12 hours of continuous use. Real-world use is sporadic, so a tank often lasts a full season.

How Long Does a 20-lb BBQ Propane Tank Last?

A 20-lb tank holds 4.7 gallons of liquid propane, equivalent to about 430,000 BTU of energy. The duration depends entirely on your grill's BTU rating and how many burners you run.

Grill type	BTU rating	Hours per tank	Cooks per tank (avg 1 hr cook)
Compact / portable	12,000-20,000 BTU/hr	21-36 hours	20-30 cooks
Mid-size 3-burner	30,000-40,000 BTU/hr	11-14 hours	11-14 cooks
Large 4-5 burner	45,000-60,000 BTU/hr	7-9.5 hours	7-10 cooks
Premium (6+ burners, side burner)	70,000-90,000 BTU/hr	5-6 hours	5-6 cooks

Most home cooks don't run all burners on full. Real-world tank life is typically 1.5-2x the table values. Cold weather reduces vapour pressure and can make a half-empty tank deliver insufficient flow on a chilly day.

How Long Does the Tank Itself Last?

Tank Type	Typical lifespan	Failure modes
Above-ground residential (250-1000 gal)	30-40 years	Surface rust, valve seal degradation, gauge failure
Underground residential	30-50 years (with cathodic protection)	Coating failure, cathodic protection failure
20-lb refillable BBQ	Indefinite (12-year recertification)	Valve degradation, dent/damage from transport, certification expiry
100-lb cylinder	20-30 years	Valve damage, surface rust, recertification failure

What wears out before the tank does: the regulator (replace every 15-25 years), the supply line connections (visual inspect annually), the gauge mechanism (replace if stuck or inaccurate), and the OPD valve seals (rare failure). A reputable supplier inspects the tank during every refill — if they spot a problem, they will refuse the fill until it is fixed.

Tank Duration FAQ

How long does a 500-gallon propane tank last?

A 500-gallon propane tank holds 400 usable gallons (80% rule). For a typical 2,000 sqft home using propane for heating, that lasts 4 to 7 months in winter. For homes using propane only for water heating and cooking (200-400 gal/year), a 500-gallon tank can last 12 to 24 months. Heating households typically refill every 2 to 4 months during the heating season.

How long does a 20-lb propane tank last on a grill?

A 20-lb propane tank holds about 4.7 gallons of liquid propane (~430,000 BTUs). On a typical 30,000 BTU/hour mid-size grill, that lasts 14 to 20 hours of cooking — roughly 18 to 20 backyard cooks. On a larger 60,000 BTU/hour grill, expect 7 to 10 hours of use. Tank duration varies with weather (cold weather slows vapour pressure) and grill efficiency.

How long does a propane tank last for a generator?

A 500-gallon home tank running a 20-kW standby generator at half load (~2 gal/hour fuel use) lasts about 200 hours of continuous run-time, or 8-9 days. At full load, fuel burn doubles to ~4 gal/hour and run-time drops to about 4 days. For genuine extended outages (1-2 weeks), most homeowners install a dedicated 500-1000 gallon generator tank in addition to their heating tank.

How long do propane tanks last before they need replacing?

Above-ground residential propane tanks last 30 to 40 years with proper maintenance. Underground tanks with adequate corrosion protection (cathodic protection plus coating) can last 30 to 50 years. The tank itself rarely fails — what wears out are the regulator (replace every 15-25 years), supply line connections (visual check annually), and the gauge mechanism (replace if stuck). A reputable supplier will pull a tank from service if any inspection turns up corrosion, valve issues, or coating failure.

Do small propane tanks (1 lb) expire?

Disposable 1-lb propane bottles do not expire in the legal sense, but US DOT regulations require non-refillable cylinders to be discarded after first use. Refillable 1-lb cylinders (Flame King, Ignik) can be re-used indefinitely if visually undamaged. For 4-lb and larger refillable tanks, a recertification stamp is required every 12 years (every 5 years for the first inspection).

Can a propane tank go bad?

Liquid propane itself does not degrade or expire — chemically it is stable indefinitely in a sealed tank. What can go bad: the rubber seals on the valve (replace every 10-15 years), the regulator (replace every 15-25 years), any rust or corrosion on the tank body (sand and repaint or replace), and the gauge mechanism. A tank that has been sitting unused for 5+ years should be inspected before refilling — especially if stored outdoors.

Plan your next fill|Tank sizes|20-lb BBQ tank guide

About the author

Oliver Wakefield-Smith

Founder of Digital Signet, an independent research firm that builds data-led pricing and decision tools for US homeowners. PropaneCostPerGallon.com is built from the EIA's weekly residential propane survey, supplier-quoted retail rates, and real fill-up receipts collected from readers.

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