330 gallon horizontal oil tank chart
The 330 horizontal is the biggest of the common oval tanks and the easiest to misjudge: 44″ wide, 27″ tall, 72″ long. All 329 gallons hide under a stick scale that tops out at 27 inches, so a small change in inches is a big change in gallons. Read the wet line and convert below.
gallons % of a full 330 gallon horizontal tank
Enter a reading to convert it, fill the tank pictures, and highlight your row in the chart below.
| Inches | Gallons | Inches | Gallons |
|---|---|---|---|
| 1″ | 8 | 15″ | 185 |
| 2″ | 17 | 16″ | 199 |
| 3″ | 27 | 17″ | 213 |
| 4″ | 39 | 18″ | 227 |
| 5″ | 50 | 19″ | 240 |
| 6″ | 63 | 20″ | 253 |
| 7″ | 75 | 21″ | 266 |
| 8″ | 89 | 22″ | 278 |
| 9″ | 102 | 23″ | 290 |
| 10″ | 116 | 24″ | 301 |
| 11″ | 129 | 25″ | 312 |
| 12″ | 143 | 26″ | 321 |
| 13″ | 157 | 27″ | 329 |
| 14″ | 171 |
Generated 2026-06-12. Computed from nominal tank geometry at 231 cubic inches per gallon, with a 2.2 percent dished-head allowance calibrated to the manufacturer’s published capacity chart. Matches the chart books oil dealers use within about a gallon.
Reading the numbers
- Full is about 329 gallons, the same oil a 330 vertical holds, read on a 27 inch scale instead of 44.
- Half is 13.5 inches, 164 gallons. A quarter (about 82 gallons) sits at about 8 inches.
- The middle band runs about 14 gallons per inch, the steepest of the household ovals. The 330 vertical moves about 8.6 in its middle, the 275 horizontal about 11.7.
- At 5 inches you are near 50 gallons. That is order-today territory in the heating season.
- Confirm the length before trusting any oval chart. 72 inches end to end is a 330; 60 inches is a 275.
Common questions
Which horizontal chart do I need, 275 or 330?
Both lie 44 inches wide and 27 inches tall, so the end profile cannot tell you. Measure end to end: 60 inches is a 275, 72 inches is a 330. Then confirm against the data plate if it is legible.
How far off is the 275 horizontal chart on this tank?
About 20 percent low at any depth. At 15 inches the 275 horizontal chart shows 154 gallons; this tank actually holds about 185 at the same reading.
How many gallons per inch?
About 14 through the straight middle of the tank, tapering in the rounded top and bottom. Use the chart for the conversion rather than multiplying, especially near the curves.
Is my 330 vertical or horizontal?
Stand at the oval end. Wider than tall means horizontal, and this chart applies. Taller than wide means you want the 330 vertical chart, where the same oil reads across 44 inches.
Related
- 330 gallon vertical chart (same tank stood on end)
- 275 gallon horizontal chart (same height, one foot shorter)
- How to stick an oil tank
- How long will my oil last?