Why Tank Size Matters for Permits
The size of your propane tank is the primary factor that determines whether a permit is required for an above-ground installation. In most jurisdictions, the permit threshold sits at 125 gallons: tanks below this size often don't need a dedicated LP installation permit (though gas piping almost always does). Tanks 125 gallons and above typically require a full installation permit. Underground tanks require a permit at any size.
Size also affects setback requirements. Tanks under 500 gallons require a 10-foot setback from buildings and ignition sources under NFPA 58. Tanks 500–2,000 gallons require 25 feet. This can matter a great deal on smaller lots.
Tank Size Comparison Table
| Tank Size | Dimensions (approx.) | Usable Capacity | Typical Use | Above-Grd Permit | NFPA 58 Setback |
|---|---|---|---|---|---|
| 120 gal | 4 ft × 24 in dia | ~96 gal | Single appliance, grill, space heater | Often not required | 10 ft |
| 250 gal | 7.5 ft × 30 in dia | ~200 gal | Small home supplement, water heater | Often required at 125+ gal | 10 ft |
| 500 gal | 10 ft × 37 in dia | ~400 gal | Whole-home heating (up to ~2,500 sq ft) | Required most jurisdictions | 10 ft |
| 1,000 gal | 15 ft × 41 in dia | ~800 gal | Large home, farm, generator | Required everywhere | 25 ft |
How to Size Your Tank: The Basic Framework
Step 1: Identify all propane-using appliances
List every appliance that will use propane: furnace or boiler, water heater, cooking range, dryer, fireplace logs, generator, pool heater. Each has a BTU rating listed on the nameplate. Your LP gas contractor will sum these to calculate total connected load.
Step 2: Estimate annual consumption
Propane consumption depends heavily on climate and home insulation. Rough estimates for whole-home heating:
- Warm climate (South, Southwest): 400–800 gallons per year for heating
- Moderate climate (Mid-Atlantic, Midwest): 700–1,200 gallons per year
- Cold climate (Upper Midwest, New England): 1,000–2,000+ gallons per year
Add approximately 200–400 gallons per year for a propane water heater, 30–50 gallons for a range, and 100–200 gallons for a dryer.
Step 3: Choose delivery frequency
Standard practice is to maintain the tank at 20–30% full as the minimum before delivery. At 500 gallons usable capacity and 800 gallons annual consumption, you'd need 2–3 deliveries per winter. At 1,000 gallons usable capacity, you could potentially get through a winter on 1–2 deliveries. Automatic delivery schedules from your supplier take the guesswork out.
Step 4: Consider the permit and setback implications
If you're on the fence between 500 and 1,000 gallons, remember: the 1,000-gallon tank requires a 25-foot setback vs. 10 feet for 500 gallons. On smaller properties, this can be the deciding factor. Use our Setback Calculator to compare your options.
Step 5: Use the Tank Size Wizard
Our Tank Size Wizard takes your home size, appliance use, climate zone, and delivery preference and returns a recommended tank size with permit implications in under a minute.
The 500-Gallon Decision Point
The 500-gallon tank is the most common residential choice in the United States for good reason: it's large enough for whole-home heating in most homes, it maintains the 10-foot NFPA 58 setback (vs. 25 feet for 1,000 gallons), and it's the standard size offered by virtually all propane suppliers. If your annual consumption is under 1,200 gallons and you don't have a standby generator or pool, a 500-gallon tank is usually the right choice. Full 500-gallon permit guide →
Yes, multiple tanks connected in manifold is a legitimate alternative to a single larger tank. Two 500-gallon tanks connected together have the same usable capacity as one 1,000-gallon tank, but each individual tank requires only the 10-foot setback rather than the 25-foot setback required for a 1,000-gallon tank. This can be a significant advantage on smaller properties. The manifold connecting system requires a gas piping permit and inspection. Your LP gas contractor can design and install a two-tank manifold system.
In jurisdictions that use valuation-based permit fees (calculating the fee as a percentage of the project's estimated cost), a larger, more expensive installation will generate a higher permit fee. In jurisdictions with flat permit fee schedules, the fee is the same regardless of tank size above the threshold. Underground installations always cost more to permit than above-ground, regardless of size, due to the additional review and inspection requirements. Full permit fee guide →