1000 Gallon Underground Oil Tank chart
Geometric capacity 1,018.4 gallons; usually filled to ~900 gal.
| Depth | Gallons | Liters | % Full |
|---|---|---|---|
| 1″ | 5 | 20 | 0% |
| 2″ | 14 | 55 | 1% |
| 3″ | 26 | 100 | 3% |
| 4″ | 40 | 153 | 4% |
| 5″ | 56 | 213 | 6% |
| 6″ | 74 | 278 | 7% |
| 7″ | 92 | 348 | 9% |
| 8″ | 112 | 422 | 11% |
| 9″ | 132 | 500 | 13% |
| 10″ | 154 | 582 | 15% |
| 11″ | 176 | 666 | 17% |
| 12″ | 199 | 754 | 20% |
| 13″ | 223 | 843 | 22% |
| 14″ | 247 | 935 | 24% |
| 15″ | 272 | 1,029 | 27% |
| 16″ | 297 | 1,125 | 29% |
| 17″ | 323 | 1,222 | 32% |
| 18″ | 349 | 1,320 | 34% |
| 19″ | 375 | 1,420 | 37% |
| 20″ | 402 | 1,520 | 39% |
| 21″ | 428 | 1,622 | 42% |
| 22″ | 455 | 1,723 | 45% |
| 23″ | 482 | 1,825 | 47% |
| 24″ | 509 | 1,927 | 50% |
| 25″ | 536 | 2,030 | 53% |
| 26″ | 563 | 2,132 | 55% |
| 27″ | 590 | 2,233 | 58% |
| 28″ | 617 | 2,335 | 61% |
| 29″ | 643 | 2,435 | 63% |
| 30″ | 670 | 2,535 | 66% |
| 31″ | 696 | 2,633 | 68% |
| 32″ | 721 | 2,730 | 71% |
| 33″ | 746 | 2,826 | 73% |
| 34″ | 771 | 2,920 | 76% |
| 35″ | 796 | 3,012 | 78% |
| 36″ | 819 | 3,101 | 80% |
| 37″ | 842 | 3,189 | 83% |
| 38″ | 865 | 3,273 | 85% |
| 39″ | 886 | 3,355 | 87% |
| 40″ | 907 | 3,433 | 89% |
| 41″ | 926 | 3,507 | 91% |
| 42″ | 945 | 3,577 | 93% |
| 43″ | 962 | 3,642 | 94% |
| 44″ | 978 | 3,701 | 96% |
| 45″ | 992 | 3,755 | 97% |
| 46″ | 1,004 | 3,800 | 99% |
| 47″ | 1,013 | 3,835 | 100% |
| 48″ | 1,018 | 3,855 | 100% |
What is the same for every tank of this kind (how to stick underground oil tanks, why your reading may not match a chart, the standards behind underground oil tanks) is set out once on the charts hub, in the underground oil tank reference and the common questions for every chart.
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 27.00 gallons; at the narrowest it is 5.20 gallons — a factor of 5.2×. 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 (25″) | 27.00 gal | 102.2 L |
| One inch at the narrowest point (48″) | 5.20 gal | 19.7 L |
| Average inch across the full depth | 21.22 gal | 80.3 L |
| ⅛-inch reading error, worst case | 3.38 gal | 12.78 L |
| ½-inch reading error, worst case | 13.50 gal | 51.1 L |
Where this chart's geometry comes from
Dimensions modelled: Common 48 x 130 in cylinder. Geometry yields 1018 gal. 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 1,000 gal; geometry as modelled 1,018.4 gal — where your tank's maker publishes a chart for it, prefer that one when the two disagree.
FAQ
How many gallons are in my 1000 gallon underground oil tank at half depth?
About 509 gallons at 24 inches. This shell is symmetric, so half the depth is also half the volume.
How accurate does my stick reading need to be?
On this tank an eighth of an inch is worth up to 3.38 gallons and half an inch up to 13.5 gallons at the steepest part of the curve, so read to the nearest eighth for a reconciliation and to the nearest half inch for a rough check.
Sources and standards
- 40 CFR § 280.43 — Methods of release detection for tanksU.S. Environmental Protection Agency, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-40/chapter-I/subchapter-I/part-280/subpart-D/section-280.43
- 40 CFR Part 280 — Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage TanksU.S. Environmental Protection Agency, via the electronic Code of Federal Regulationshttps://www.ecfr.gov/current/title-40/chapter-I/subchapter-I/part-280
- UL 80 — Standard for Steel Tanks for Oil-Burner Fuel and Other Combustible Liquids; UL 58 — Steel Underground Tanks for Flammable and Combustible LiquidsUL Standards & EngagementPaid standard — cited by designation; obtain from the publisher.
- NFPA 31 — Standard for the Installation of Oil-Burning EquipmentNational Fire Protection AssociationPaid standard — cited by designation; obtain from the publisher.
- 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-c
- ISO 7507-1 — Petroleum and liquid petroleum products: Calibration of vertical cylindrical tanks, Part 1: Manual strapping methodInternational Organization for StandardizationPaid standard — cited by designation; obtain from the publisher.
- Methodology — the partial-fill formulas and liquid densities used on this sitetankvolumecalc.comhttps://tankvolumecalc.com/methodology/
Every linked source above was retrieved and checked on 2026-09-02.