Common US propane tank sizes
Two physically different tank families serve US customers. DOT cylinders are portable, refilled at exchange points, and used for grills, RVs and small appliances. ASME tanks are permanently installed, larger, and used for home heating and whole-house loads. Both are filled to 80% of their water capacity — the remaining 20% is vapor space for thermal expansion, mandated by NFPA 58.
| Tank | Usable (~80% fill) | Typical use |
|---|---|---|
| 20 lb cylinder | ~4.7 gal | Grills, patio heaters, small RVs |
| 30 / 40 lb cylinder | ~7 / ~9 gal | RVs, food trucks, larger grills |
| 100 lb cylinder | ~23 gal | Cooking + dryer + fireplace; no central heat |
| 120 gal ASME | ~96 gal | Cooking + water heat + small backup heat |
| 250 gal ASME | ~200 gal | Small home heat, water heat, range |
| 500 gal ASME | ~400 gal | Standard whole-home heating tank — the US default |
| 1,000 gal ASME | ~800 gal | Large homes, light commercial, standby generators, agricultural |
The 500-gallon aboveground ASME is the US residential default and what most propane heating customers end up with. Sub-250-gallon installations rarely make sense for whole-home heating because the delivery economics work against you (more frequent fills, higher per-gallon rates, more delivery surcharges).
How to size from appliance BTU ratings
A gallon of propane delivers 91,500 BTU. Every gas appliance has a nameplate BTU/hour rating printed on a sticker or in the manual. Multiply hours of operation by the appliance's BTU/hour rating, divide by 91,500, and you have your gallons per period.
Worked example: an 80,000 BTU/hour propane furnace running at full capacity for one hour consumes 0.87 gallons (80,000 ÷ 91,500). In a moderate climate it might run roughly 1,500 hours per heating season, for total seasonal furnace consumption around 1,300 gallons. Add water heater (~200 gal/year for a typical household), cooking (~30 gal/year) and dryer (~25 gal/year) to get a whole-home figure.
For the appliance-by-appliance walkthrough see BTUs and propane appliance ratings, and for a household-level estimator calculate your propane usage.
Aboveground vs underground tanks
Both options use the same ASME-stamped tank, just different installation. Aboveground tanks are cheaper to install ($500–$1,500 setup), easier to inspect visually, and serviceable indefinitely with paint and routine maintenance. Underground tanks cost more upfront ($1,500–$3,500 with excavation), but disappear from view (only a dome shows above grade) and add some weather protection in extreme heat. Both have a 30+ year service life when properly installed.
HOA aesthetics, local zoning and lot size often decide for you. See aboveground vs underground tanks for the full comparison and NFPA 58 distance rules for setback requirements.
Lease vs buy
Most US residential propane tanks are leased — the dealer owns the tank, charges a small annual rent (often $50–$150, frequently waived above a minimum annual purchase), and you commit to refilling exclusively with them. Customer-owned tanks cost $1,000–$3,500 upfront for a typical 500-gallon aboveground unit but unlock the freedom to shop multiple dealers at every fill.
For high-volume customers (1,000+ gallons per year), customer-owned tanks usually pay back the upfront cost within 3–5 heating seasons. For light users (under 300 gal/year), the lease typically wins on total cost. See buying or renting a propane tank and propane tank price for the math.
A few states have anti-fill laws that constrain how a dealer can lock a customer to a leased tank (e.g. mandatory disclosure, capped pickup fees). Most do not — check your state page for local rules.
Why a larger tank usually wins
Beyond the obvious — fewer fills per year, less risk of running out — there are two structural reasons to size up rather than down.
- Better per-gallon rates on larger fills. Dealers price gallons cheaper at 300+ gallon fills than at 100-gallon top-offs. A bigger tank lets you order bigger fills.
- Pre-buy flexibility. Larger tanks accommodate the summer pre-buy quantities that lock in cheap rates before winter. A 250-gallon tank can't hold a 400-gallon pre-buy. See summer propane fill.
The standard recommendation: pick a tank that holds at least 6 months of winter consumption at 80% capacity. For most US homes heating with propane, that means a 500-gallon aboveground. For homes in the very coldest climates with full propane appliance loads — large square footage in Maine, Wyoming, Montana, Minnesota — step up to 1,000 gallons.
Installation considerations
Tank placement on your property is governed by NFPA 58 setback rules, summarized below for the residential range:
- Under 125 gal water capacity: 0 ft minimum from buildings (with restrictions on openings).
- 125–500 gal: 10 ft from buildings and property lines.
- 501–2,000 gal: 25 ft from buildings and property lines.
- Underground (residential range): 10 ft from buildings and property lines regardless of size.
- Fill valve and vents: minimum 10 ft from any ignition source or building opening.
Local jurisdictions may impose stricter rules. Permitting is required for new installations in nearly all states. See tank distance requirements, permits, and installation cost.
Frequently asked questions
What is the most common residential propane tank size?
The 500-gallon aboveground ASME tank is the standard US residential heating tank — used by the majority of households where propane is the primary heating fuel. Smaller homes or households using propane only for cooking, water heating and outdoor living often run a 120 or 250-gallon tank instead.
How long does a 500-gallon propane tank last?
A full 500-gallon tank holds ~400 usable gallons. A typical 2,000 sq ft home heating with propane in a moderate climate burns 800–1,200 gallons per winter, so a 500-gallon tank covers roughly 2–4 months of peak heating-season use on a single fill. In very cold climates with large square footage, plan on more frequent fills or step up to a 1,000-gallon tank.
Should I buy or lease my propane tank?
Buy if you burn 1,000+ gallons per year and plan to stay in the home long enough for the tank to pay back. Lease if you burn under 300 gallons per year or are short-term in the home. The full decision framework is on buying or renting a propane tank.
Is an underground propane tank worth the extra cost?
For aesthetic-sensitive properties (HOAs, lakefront, design-driven landscaping) usually yes. For functional-only installations, rarely — the additional $1,000–$2,000 in installation cost buys appearance and modest temperature stability rather than meaningful operational advantage.
Going further
Browse the tanks cluster for more depth, especially: