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WELLFLINT GUIDES
Oil tank barrels per inch calculator
Updated October 28, 2026 · By Ben Tremblay, founder of WellFlint
Short answer: a 10 foot wide tank (the usual 210 barrel tank) holds about 1.17 barrels per inch. A 12 foot wide tank (the usual 300 and 400 barrel tanks) holds about 1.68 barrels per inch. One barrel is 5.6146 cubic feet.
Calculator
Leave the closing gauge at zero to get the barrels in the tank at the opening gauge. To keep one in the truck, print an inch-by-inch chart for this tank.
WellFlint runs this same math on every gauge your pumper records, so the office sees barrels without retyping tickets. See how it works.
Barrels per inch for common oil tanks
| Nominal tank | Size (wide × tall) | bbl per inch | bbl per ¼ inch | bbl per foot |
|---|---|---|---|---|
| 90 bbl | 7 ft 11 in × 10 ft | 0.73 | 0.18 | 8.8 |
| 100 bbl | 9 ft 6 in × 8 ft | 1.05 | 0.26 | 12.6 |
| 150 bbl | 9 ft 6 in × 12 ft | 1.05 | 0.26 | 12.6 |
| 200 bbl | 12 ft × 10 ft | 1.68 | 0.42 | 20.1 |
| 210 bbl | 10 ft × 15 ft | 1.17 | 0.29 | 14.0 |
| 250 bbl | 11 ft × 15 ft | 1.41 | 0.35 | 16.9 |
| 300 bbl | 12 ft × 15 ft | 1.68 | 0.42 | 20.1 |
| 400 bbl | 12 ft × 20 ft | 1.68 | 0.42 | 20.1 |
| 500 bbl | 15 ft 6 in × 16 ft | 2.80 | 0.70 | 33.6 |
| 750 bbl | 15 ft 6 in × 24 ft | 2.80 | 0.70 | 33.6 |
| 1,000 bbl | 15 ft 6 in × 30 ft | 2.80 | 0.70 | 33.6 |
Sizes follow API 12F, the standard for welded lease tanks. Many builders make the 500, 750 and 1,000 bbl tanks 15 ft 3 in wide instead of 15 ft 6 in, which is 2.71 bbl per inch, and some 1,000 bbl tanks are 32 ft tall. A 500 bbl tank also comes 12 ft wide and 25 ft tall. Measure the diameter of your own tanks, or better, use the strapping table that came with them.
Oil tank chart by the foot
Gross barrels in an upright tank at each foot of gauge. For a gauge between feet, add the inches times the barrels per inch above.
| Gauge | 210 bbl (10 ft wide) | 300 or 400 bbl (12 ft wide) | 500 bbl (15 ft 6 in wide) |
|---|---|---|---|
| 1 ft | 14.0 | 20.1 | 33.6 |
| 2 ft | 28.0 | 40.3 | 67.2 |
| 3 ft | 42.0 | 60.4 | 100.8 |
| 4 ft | 56.0 | 80.6 | 134.4 |
| 5 ft | 69.9 | 100.7 | 168.0 |
| 6 ft | 83.9 | 120.9 | 201.6 |
| 7 ft | 97.9 | 141.0 | 235.3 |
| 8 ft | 111.9 | 161.1 | 268.9 |
| 9 ft | 125.9 | 181.3 | 302.5 |
| 10 ft | 139.9 | 201.4 | 336.1 |
| 11 ft | 153.9 | 221.6 | 369.7 |
| 12 ft | 167.9 | 241.7 | 403.3 |
| 13 ft | 181.9 | 261.9 | 436.9 |
| 14 ft | 195.8 | 282.0 | 470.5 |
| 15 ft | 209.8 | 302.2 | 504.1 |
| 16 ft | 223.8 | 322.3 | 537.7 |
| 17 ft | 237.8 | 342.4 | 571.3 |
| 18 ft | 251.8 | 362.6 | 604.9 |
| 19 ft | 265.8 | 382.7 | 638.5 |
| 20 ft | 279.8 | 402.9 | 672.1 |
A 210 bbl tank is usually 15 feet tall and a 300 bbl tank 15 or 16 feet, so stop reading those columns at the top of your tank.
Make an inch-by-inch chart for the tank picked in the calculator
Standard oil tank dimensions
- 90 bbl: 7 ft 11 in wide × 10 ft tall.
- 100 and 150 bbl: 9 ft 6 in wide × 8 ft and 12 ft tall.
- 200 bbl: 12 ft wide × 10 ft tall.
- 210 bbl: 10 ft wide × 15 ft tall.
- 300 bbl: 12 ft wide × 15 ft tall.
- 400 bbl: 12 ft wide × 20 ft tall.
- 500 bbl: 15 ft 6 in wide × 16 ft tall, or 12 ft wide × 25 ft tall.
- 750 bbl: 15 ft 6 in wide × 24 ft tall.
- 1,000 bbl: 15 ft 6 in wide × 30 ft tall.
These are the API 12F sizes for welded lease tanks, and bolted tanks come close to them. Builders vary, so check the nameplate or measure around the tank and divide by 3.1416 to get the diameter.
The formula
Barrels per inch = π × (diameter in feet ÷ 2)² ÷ 12 ÷ 5.6146
Gauge in inches = feet × 12 + inches + quarters ÷ 4
Gross barrels = (opening gauge − closing gauge) × barrels per inch
Why a quarter inch matters
On a 12 foot tank, a quarter inch is about 0.42 barrels. Misread one gauge by a quarter inch on 20 tanks every round, and the error adds up to whole loads over a month. Write gauges down at the tank, and photograph the run ticket before the truck leaves. More on that in our run ticket reconciliation guide. The last gauge of the month is also your ending stock on the Texas Form PR, due the last day of the following month.
Common questions
How many barrels per inch is a 210 barrel tank?
A standard 210 barrel tank is 10 feet across, which holds about 1.17 barrels per inch, or about 14.0 barrels per foot.
How many barrels per inch is a 400 barrel tank?
A 400 barrel tank that is 12 feet across holds about 1.68 barrels per inch. A 300 barrel tank is usually also 12 feet across, so it has the same barrels per inch, just less height.
What are the dimensions of a 400 barrel tank?
A standard 400 barrel oil tank is 12 feet wide and 20 feet tall. At 1.68 barrels per inch it holds about 403 barrels when full to the top.
How many barrels per inch is a 500 barrel tank?
A 500 barrel tank built to API 12F is 15 feet 6 inches across, about 2.80 barrels per inch. Many are built 15 feet 3 inches across, about 2.71 barrels per inch. The taller 12 foot wide version holds 1.68 barrels per inch.
What are the dimensions of a 750 barrel tank?
API 12F sizes a 750 barrel tank at 15 feet 6 inches wide and 24 feet tall, about 2.80 barrels per inch. Many builders make it 15 feet 3 inches wide, which is about 2.71 barrels per inch.
How do I work out barrels from a tank gauge?
Convert the gauge to inches (feet × 12 + inches + quarters ÷ 4), then multiply by the tank's barrels per inch. For a load, subtract the closing gauge from the opening gauge first.
Is this the same as my strapping table?
No. This calculator treats the tank as a perfect upright cylinder. Real tanks have bottoms, dents and fittings, so your tank's strapping table is the number to use for sales and reporting.
Why are gross barrels different from net barrels?
Gross barrels come straight from the gauges. Net barrels are corrected to 60°F and have BS&W deducted, which is what the purchaser pays on. The net oil calculator does that step.