55 Gallon Drum chart
Geometric capacity 57.7 gallons. A standard tight-head drum actually holds ~57.7 gal brim-full; 55 gal is the rated working capacity.
| Depth | Gallons | Liters | % Full |
|---|---|---|---|
| 1″ | 2 | 7 | 3% |
| 2″ | 3 | 13 | 6% |
| 3″ | 5 | 20 | 9% |
| 4″ | 7 | 26 | 12% |
| 5″ | 9 | 33 | 15% |
| 6″ | 10 | 39 | 18% |
| 7″ | 12 | 46 | 21% |
| 8″ | 14 | 52 | 24% |
| 9″ | 16 | 59 | 27% |
| 10″ | 17 | 65 | 30% |
| 11″ | 19 | 72 | 33% |
| 12″ | 21 | 78 | 36% |
| 13″ | 22 | 85 | 39% |
| 14″ | 24 | 91 | 42% |
| 15″ | 26 | 98 | 45% |
| 16″ | 28 | 104 | 48% |
| 17″ | 29 | 111 | 51% |
| 18″ | 31 | 117 | 54% |
| 19″ | 33 | 124 | 57% |
| 20″ | 34 | 130 | 60% |
| 21″ | 36 | 137 | 63% |
| 22″ | 38 | 143 | 66% |
| 23″ | 40 | 150 | 69% |
| 24″ | 41 | 156 | 72% |
| 25″ | 43 | 163 | 75% |
| 26″ | 45 | 169 | 78% |
| 27″ | 46 | 176 | 81% |
| 28″ | 48 | 182 | 84% |
| 29″ | 50 | 189 | 87% |
| 30″ | 52 | 195 | 90% |
| 31″ | 53 | 202 | 92% |
| 32″ | 55 | 208 | 96% |
| 33″ | 57 | 215 | 98% |
| 33.5″ | 58 | 218 | 100% |
How to measure this container
Measure liquid depth from the inside bottom, straight up to the surface, with a clean rule or stick held vertical. For IBC totes, the molded gallon/liter markings on the bottle are more accurate near the corners than any rectangular model — use the chart for in-between readings and the markings as your anchor points.
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 1.80 gallons; at the narrowest it is 0.90 gallons — a factor of 2.0×. 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.
| Measure | Gallons | Litres |
|---|---|---|
| One inch at the widest point (8″) | 1.80 gal | 6.8 L |
| One inch at the narrowest point (33.5″) | 0.90 gal | 3.4 L |
| Average inch across the full depth | 1.70 gal | 6.4 L |
| ⅛-inch reading error, worst case | 0.23 gal | 0.85 L |
| ½-inch reading error, worst case | 0.90 gal | 3.4 L |
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:
- Nominal 55 gallons is the rated capacity, not the brim capacity. A standard tight-head steel drum holds meaningfully more than 55 gallons brim-full; the rating is a fill capacity with outage allowed for expansion.
- Rolling hoops and chimes are outside the liquid. Measure the internal height from the inside bottom, not the overall drum height.
- Drums are almost never level. On a pallet or a dolly, a couple of degrees of tilt across 22.5 inches of diameter moves the reading by close to an inch.
- Dents change the geometry permanently. A reconditioned drum with a dished side no longer matches a cylinder model. Weigh it, or trust the fill meter.
The standards behind this container
Steel drums for regulated materials are built to 49 CFR § 178.504 and coded under § 178.502: 1A1 for a non-removable (tight) head and 1A2 for a removable (open) head. Openings larger than 3 inches make a drum removable-head by definition. The older DOT-17E designation you still see quoted in trade literature was superseded by these UN performance-oriented standards, and a modern drum carries a UN mark rather than a 17E stamp.
The nominal 55 gallons is a rated fill capacity, not a brim capacity — a standard tight-head drum holds several gallons more before it overflows, and the difference is deliberate outage for thermal expansion.
For storage, the SPCC rule treats drums as portable containers under 40 CFR § 112.8(c)(11): secondary containment must hold the largest single container plus freeboard, which for a single 55-gallon drum means a sump of at least 55 gallons, not the 30-gallon two-drum platforms often sold for the purpose.
Where this chart's geometry comes from
Dimensions modelled: UN 1A1 tight-head steel drum per 49 CFR § 178.504 (the legacy DOT-17E designation it superseded is still widely quoted); industry standard 22.5 in ID x 33.5 in interior height. 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 55 gal; geometry as modelled 57.7 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.
FAQ
How many gallons are in my 55 gallon drum at half depth?
About 29 gallons at 17 inches. This shell is symmetric, so half the depth is also half the volume — which is not true of every tank, and is worth checking before you assume it. Use the reader above for any specific depth.
How accurate does my stick reading need to be?
On this tank an eighth of an inch is worth up to 0.23 gallons and half an inch up to 0.9 gallons at the steepest part of the curve. Read to the nearest eighth if the number is going into a reconciliation; to the nearest half inch if you just want to know whether to order fuel.
Where exactly do I measure from?
The inside bottom of the tank, straight up to the wet line, with the stick vertical. Not from the fill-pipe rim, not from the top of a riser, and not from outside the shell. If the fill pipe is angled, the stick still has to end up vertical inside the tank or the reading runs long.
Why does my manufacturer's chart differ by a gallon or two?
Because it describes that specific tank and this one describes the stated geometry. Corner radii, internal ribs, head shape and wall thickness typically account for 1–3 %. Where the two disagree and the number matters, the manufacturer's chart for your serial number wins — and for anything that gets invoiced, neither substitutes for a calibration under ISO 7507-1.
Is the nominal capacity the same as brim-full?
No. The rated figure is a fill capacity with outage left for thermal expansion; brim-full is higher. For a regulated container the authoritative number is the rated capacity in the UN marking, not the figure stencilled on the cage or the trade name.
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 steel drum in service.
- 49 CFR § 178.504 — Standards for steel drums (and § 178.502, identification codes)U.S. Pipeline and Hazardous Materials Safety Administration, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-178/subpart-L/section-178.504The current federal standard for steel drums. Codes are 1A1 (non-removable head) and 1A2 (removable head); openings over 3 inches make a drum removable-head by definition. The legacy DOT-17E designation was superseded by these UN performance-oriented standards.
- 49 CFR Part 178 — Specifications for Packagings (Subpart N: Intermediate Bulk Containers)U.S. Pipeline and Hazardous Materials Safety Administration, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-178Design, construction, marking and periodic retest requirements for IBCs. The UN marking moulded into a tote's bottle records its design type, packing group, test date and rated capacity — read it before trusting a nominal gallon figure.
- 40 CFR § 112.8(c)(2) — Spill Prevention, Control, and Countermeasure Plan requirements for onshore facilitiesU.S. Environmental Protection Agency, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-40/chapter-I/subchapter-D/part-112/subpart-B/section-112.8Requires secondary containment sized for the entire capacity of the largest single container, plus sufficient freeboard to contain precipitation. Note that the rule itself does not state “110 %” — that is a common design convention layered on top of the regulatory floor.
- 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).
- 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.
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.