250 Gallon Propane Tank chart

Reading the gauge (don't stick a propane tank)

Propane vessels are sealed pressure vessels — you never open or stick them. Read the float gauge on top: it shows percent of water capacity, and gallons of propane = gauge % × water capacity. The inch table below is the underlying geometry, useful for cross-checking a suspect gauge against a delivery ticket. Maximum legal fill is 80%, so a healthy gauge tops out around there after a delivery.

What one inch is worth on this tank

An inch is not an inch on this tank. At the widest point one inch of depth is 10.70 gallons; at the narrowest it is 2.40 gallons — a factor of 4.5×. That is exactly why interpolating linearly between two distant chart rows goes wrong, and why the reader above computes the value rather than averaging neighbours.

Why your reading may not match this chart

The arithmetic on this page is exact for the geometry stated below. The disagreements you will actually see come from the tank and the measurement, not the maths — in roughly this order of size:

• The float gauge reads percent of water capacity, not gallons. Multiply the gauge percentage by the tank's water capacity to get gallons of propane. A gauge reading 40 % on this vessel is not 40 % of the propane you can legally carry.
• Float gauges are approximate by design. They are magnetic dial gauges with a float arm, typically accurate to a few percent, and they stick. A reading that has not moved in a week during heating season is a gauge fault until proven otherwise.
• Temperature moves the liquid level visibly. Propane's volumetric expansion coefficient is roughly six times water's. The same mass of propane reads noticeably higher on a hot afternoon than at dawn.
• Never open or stick a propane vessel. It is a sealed pressure vessel under roughly 100–200 psi in summer conditions. The inch table on this page is geometry for cross-checking a suspect gauge against a delivery ticket, not an invitation to gauge manually.

The standards behind this vessel

Stationary propane containers are pressure vessels built to ASME Boiler and Pressure Vessel Code Section VIII, Division 1. The nameplate stamps the water capacity and design pressure, and on a pressure vessel the nameplate — not a tape measure — is the authoritative capacity. That is why the chart on this page solves the shell length so the computed geometry matches the nameplate rather than the other way round.

Siting is governed by two documents that do not entirely agree. OSHA's 29 CFR § 1910.110, Table H-23 sets minimum distances by water capacity: 10 ft to the nearest important building for containers up to 500 gallons, 25 ft for 501–2,000 gallons (reducible to 10 ft for a single container of 1,200 gallons water capacity or less that is at least 25 ft from any other LP-gas container over 125 gallons), and 50 ft for 2,001–30,000 gallons. Most states adopt NFPA 58 instead or as well, and its Table 6.4.1.1 differs — notably for containers of 125 gallons and under. Confirm which your jurisdiction enforces before siting anything.

Fill limits come from NFPA 58: a container equipped with a fixed maximum liquid level gauge is filled to roughly 80 % of water capacity, leaving vapour space for thermal expansion. Propane's expansion coefficient is about six times water's, which is what that headspace is protecting against.

Where this chart's geometry comes from

Dimensions modelled: Nominal 30 in dia ASME vessel; length solved to nameplate capacity. Every value in the table is computed from that geometry with a closed-form partial-fill formula — a circular or obround segment for the shell, plus scaled spherical caps where the vessel has dished heads. No interpolation, no curve fitting, no lookup tables. The derivations and the automated tolerance tests that gate each build are on the methodology page.

Nominal capacity 250 gal; geometry as modelled 250.0 gal. Where a manufacturer publishes a chart for your specific tank, that chart describes your tank and this one describes the standard geometry — prefer theirs when the two disagree and the number matters.

Sources and standards

The geometry on this page is computed, not copied. These are the documents that define the units it is expressed in and the codes that govern a propane vessel in service.

1. 29 CFR § 1910.110 — Storage and handling of liquefied petroleum gases (Table H-23, minimum distances)U.S. Occupational Safety and Health Administration, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-29/subtitle-B/chapter-XVII/part-1910/subpart-H/section-1910.110Federal separation distances for LP-gas containers, by water capacity: under 125 gal — 10 ft above ground; 125–250 gal — 10 ft; 251–500 gal — 10 ft and 3 ft between containers; 501–2,000 gal — 25 ft (reducible to 10 ft for a single container of 1,200 gal water capacity or less, if it is at least 25 ft from any other LP-gas container over 125 gal); 2,001–30,000 gal — 50 ft.
2. NFPA 58 — Liquefied Petroleum Gas Code (separation distances, Table 6.4.1.1; filling limits, Ch. 7)National Fire Protection AssociationPaid standard — cited by designation; obtain from the publisher.The model code most US states adopt for propane installations, and the one your local inspector is most likely working from. It is not identical to OSHA's Table H-23 — notably for containers of 125 gal water capacity and under — so confirm which is enforced locally. NFPA publishes free read-only access to its codes at nfpa.org.
3. ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 — Rules for Construction of Pressure VesselsAmerican Society of Mechanical EngineersPaid standard — cited by designation; obtain from the publisher.Stationary propane containers are ASME vessels. The nameplate stamps water capacity, design pressure and the manufacturer's data — and the nameplate, not a tape measure, is the authoritative capacity for a pressure vessel.
4. Handbook 44, Appendix C — General Tables of Units of MeasurementNational Institute of Standards and Technology, U.S. Department of Commercehttps://www.nist.gov/document/2026-nist-handbook-44-appendix-cThe legal-metrology reference for U.S. customary units. Fixes the U.S. liquid gallon at exactly 231 cubic inches and tabulates the full liquid-volume chain (minim → fluid dram → fluid ounce → gill → pint → quart → gallon).
5. Methodology — the partial-fill formulas and liquid densities used on this sitetankvolumecalc.comhttps://tankvolumecalc.com/methodology/Every chart value here comes from a closed-form partial-fill formula, not interpolation: circular segments for cylinders, a piecewise obround model for 275/330 heating-oil tanks, and scaled spherical caps for dished heads. Densities and their bases are tabulated there.
6. Manual of Petroleum Measurement Standards (MPMS) — Ch. 1 “Vocabulary”, Ch. 11.1 “Temperature and Pressure Correction Factors”, Ch. 12.1 “Calculation of Static Petroleum Quantities”American Petroleum Institute (with ASTM D1250 / ISO 91 volume correction tables)Paid standard — cited by designation; obtain from the publisher.The industry standard for turning a gauged tank volume into a traded quantity: observed volume, gross standard volume at 60 °F, and net standard volume after sediment and water. A unit conversion is only the first step of that chain.

Every linked source above was retrieved and checked on 2026-09-02. Factors quoted as exact are exact by definition in the cited document, not rounded by us.