Tank Volume Calculator gives full capacity and liquid volume at any fill depth for 13 tank shapes, plus weight, floor pressure, pump time and a dipstick chart in gallons or liters.
Enter inside diameter and height; fill depth is from the bottom.
Liquid, Pump, Walls & Chart
Tank Fill Level Diagram
Dipstick Chart (Depth to Volume)
| Dipstick Depth | % of Height | Liquid Volume | % of Volume | Liquid Weight |
|---|---|---|---|---|
| 3.2 in | 10% | 6.27 US gal | 10% | 52.3 lb |
| 6.4 in | 20% | 12.5 US gal | 20% | 105 lb |
| 9.6 in | 30% | 18.8 US gal | 30% | 157 lb |
| 12.8 in | 40% | 25.1 US gal | 40% | 209 lb |
| 16 in | 50% | 31.3 US gal | 50% | 261 lb |
| Yours: 18 in | 56.3% | 35.3 US gal | 56.3% | 294 lb |
| 19.2 in | 60% | 37.6 US gal | 60% | 314 lb |
| 22.4 in | 70% | 43.9 US gal | 70% | 366 lb |
| 25.6 in | 80% | 50.1 US gal | 80% | 418 lb |
| 28.8 in | 90% | 56.4 US gal | 90% | 471 lb |
| 32 in | 100% | 62.7 US gal | 100% | 523 lb |
Surface Area, Footprint & Load
| Tank Property | Value |
|---|---|
| Inside Height (Bottom to Top) | 32 in (81.3 cm) |
| Inside Surface Area (Coating, Lining) | 23 sq ft (2.14 m²) |
| Plan Area (Outline Seen from Above) | 3.14 sq ft (0.292 m²) |
| Full Weight Spread over Plan Area | 166 lb/sq ft (7.97 kPa) |
| Bottom Pressure When Full | 1.16 psi (7.97 kPa) |
| Volume per Inch at Mid-Height | 1.96 US gal/in (2.92 L/cm) |
Step-by-Step Math
- Total volume: V = π × r² × H = π × 12² × 32 = 14,476 in³.
- Liquid at depth f = 18 in: the fill is the same footprint times depth, giving 8,143 in³ (56.25% of the volume at 56.25% of the height).
- Gallons: 14,476 in³ ÷ 231 in³/gal = 62.7 US gal total, 35.3 US gal of liquid.
- Weight: 35.3 gal × 8.3454 lb/gal × SG 1 = 294 lb; bottom pressure = 18 in × 0.036127 psi/in × 1 = 0.65 psi.
- Result: 62.7 US gal Tank Volume, 35.3 US gal Filled (56.3%).
How the Tank Volume Calculator Works
Tank volume is the space inside a tank, found from its inside measurements and shape. Measure the inside diameter, length or height, pick the matching shape, and the calculator returns the full capacity and the liquid volume at the depth you read on a dipstick.
For a vertical cylinder the math is the circle area times the height. A tank 24 in across and 32 in tall holds 14,476 cubic inches. Divide by 231 cubic inches per US gallon and the full tank holds 62.7 gallons.
Many tank calculators stop at total and fill volume. The Tank Volume Calculator also works backward from a target volume to the fill depth, so you can mark a dipstick or set a float switch. It gives the liquid weight for water, diesel, gasoline and other liquids, the pressure on the tank floor, and how long a pump of a given flow takes to fill or drain it.
If you only have outside measurements, set Dimensions Measured in the Tank Volume Calculator to the outside option and enter the wall thickness. The calculator removes the wall from each side before it works out the inside volume.
Tank Volume Formulas by Shape
Each shape has its own total-volume formula, and the partly full volume needs more care in any tank whose cross-section changes with height. This table shows the formula behind each of the 13 shapes in the tool, with r for radius and L for straight length.
| Tank Shape | Total Volume | Partly Full |
|---|---|---|
| Vertical cylinder | πr2H | Same area times fill depth |
| Horizontal cylinder | πr2L | Circular segment times length |
| Rectangular or square | L × W × H | Same area times fill depth |
| Vertical capsule | πr2L + 4/3 πr3 | Spherical caps in the domes |
| Horizontal capsule | πr2L + 4/3 πr3 | Segment plus spherical cap |
| 2:1 elliptical heads | πr2L + πD3/12 | Segment plus half a cap |
| Dished F&D or Klöpper heads | πr2L + 2 × head volume | Segment plus crown and knuckle slices |
| Oval (obround) | (end area) × L | Segment plus flat-side band |
| Elliptical | π(W/2)(H/2)L | Scaled circular segment |
| Cone bottom | πR2H + cone frustum | Frustum, then cylinder |
| Cone top | πR2H + cone frustum | Cylinder, then frustum |
| Frustum | πH/3 (R2 + Rr + r2) | Frustum to the liquid line |
| Sphere | 4/3 πr3 | Spherical cap |
In a vertical cylinder or a box, volume rises evenly with depth, so 50% of the height is 50% of the volume. In a horizontal cylinder, sphere or cone, it does not. That is where most dipstick readings go wrong.
Tank Heads and Domed Ends
Many fuel and pressure tanks are a cylinder closed with curved heads, and the heads can add a large share of the volume. The flatter the head, the less it holds. The Tank Volume Calculator offers four head styles, so pick the one stamped on the tank or shown on its drawing.
| Head Type | Volume per Head | One Head on a 48 in Tank |
|---|---|---|
| Hemispherical (capsule) | 0.2618 D3 | 125 US gal |
| 2:1 elliptical | 0.1309 D3 | 62.7 US gal |
| Klöpper (DIN 28011) | 0.0990 D3 | 47.4 US gal |
| ASME flanged and dished | 0.0810 D3 | 38.8 US gal |
A flanged and dished head has a crown radius equal to the tank diameter and a knuckle radius of 6% of it. A Klöpper head uses the same crown with a 10% knuckle, following DIN 28011. On a 48 in tank, two ASME heads add about 78 gallons, while two hemispherical ends would add about 250.
Enter the straight shell length only, measured between the head seams. The tool adds each head on top and works out the partly full volume through the crown and knuckle, which a simple cylinder formula cannot do.
Partly Full Horizontal Tank Volume
A horizontal cylinder holds less per inch near the bottom and top and more through the middle. The liquid is a circular segment, with an angle set by how far the level sits from the center.
Multiply that segment area by the tank length for the liquid volume. The table below holds for any flat-ended horizontal cylinder, whatever its size.
| Fill Depth (% of Diameter) | Volume (% of Capacity) | Fill Depth (% of Diameter) | Volume (% of Capacity) |
|---|---|---|---|
| 10% | 5.2% | 60% | 62.6% |
| 20% | 14.2% | 70% | 74.8% |
| 25% | 19.6% | 75% | 80.4% |
| 30% | 25.2% | 80% | 85.8% |
| 40% | 37.4% | 90% | 94.8% |
| 50% | 50.0% | 100% | 100% |
A reading of one quarter of the diameter means only 19.6% of the tank is full, not 25%. Above the middle the effect flips, so a tank read at 75% depth holds 80.4%. The Tank Volume Calculator builds a full dipstick chart for your tank at 10%, 5%, 1 in or 2 in steps.
Gallons and Liters per Inch of Depth
For a vertical round tank, every inch of depth holds the same amount, so one number turns a dipstick reading into gallons. This table gives that number for common inside diameters.
| Inside Diameter | US Gallons per Inch | Liters per Centimeter |
|---|---|---|
| 24 in (61 cm) | 1.96 | 2.92 |
| 36 in (91 cm) | 4.41 | 6.57 |
| 48 in (122 cm) | 7.83 | 11.7 |
| 60 in (152 cm) | 12.2 | 18.2 |
| 72 in (183 cm) | 17.6 | 26.3 |
| 96 in (244 cm) | 31.3 | 46.7 |
| 120 in (305 cm) | 49.0 | 73.0 |
A 72 in diameter tank with 30 in of water holds about 30 × 17.6 = 529 gallons. For a horizontal tank, use the calculator, since gallons per inch change with every reading.
Water Tank Volume in Liters and Gallons
For a box-shaped tank, multiply length by width by height. Measured in centimeters, divide the result by 1,000 for liters. Measured in meters, multiply by 1,000. In feet, multiply cubic feet by 28.32 for liters or by 7.48 for US gallons.
| Tank Size | Unit | Cubic Volume | Liters | US Gallons |
|---|---|---|---|---|
| 60 × 30 × 30 | cm | 54,000 cm3 | 54 | 14.3 |
| 1 × 1 × 1 | m | 1 m3 | 1,000 | 264 |
| 8 × 6 × 6 | ft | 288 ft3 | 8,155 | 2,154 |
| 10 × 10 × 10 | ft | 1,000 ft3 | 28,317 | 7,481 |
| 15 × 15 × 15 | ft | 3,375 ft3 | 95,569 | 25,247 |
A 60 × 30 × 30 cm tank holds 54 liters. An 8 × 6 × 6 ft water tank holds 288 cubic feet, about 8,155 liters, and a 15 × 15 × 15 ft tank holds about 95,570 liters. If those last sizes are in meters instead, the 15 m cube holds 3,375,000 liters.
A US gallon is 231 cubic inches, or 3.785 liters, while a UK gallon is 4.546 liters, per the conversion factors in NIST Special Publication 811. A UK gallon is about 20% larger, so 100 US gallons is about 83 UK gallons. The calculator shows US gallons, UK gallons, liters, cubic meters and 42 gallon oil barrels together.
Fish Tank Volume and Water Weight
Aquarium sizes are sold by outside dimensions, but glass walls and an open top take up space. Choose Rectangular in the Tank Volume Calculator, set Dimensions Measured to Outside, Open Top, and enter the glass thickness to see the water a tank really holds.
| Tank | Outside Size (in) | Gross Gallons | Net Gallons, 1/4 in Glass | Water Weight |
|---|---|---|---|---|
| 10 gallon | 20 × 10 × 12 | 10.4 | 9.4 | 79 lb |
| 20 gallon long | 30 × 12 × 12 | 18.7 | 17.3 | 144 lb |
| 20 gallon high | 24 × 12 × 16 | 19.9 | 18.4 | 154 lb |
| 29 gallon | 30 × 12 × 18 | 28.1 | 26.1 | 218 lb |
| 55 gallon | 48 × 13 × 21 | 56.7 | 53.3 | 445 lb |
| 75 gallon | 48 × 18 × 21 | 78.5 | 74.7 | 623 lb |
A 55 gallon tank holds about 53 gallons of water with 1/4 in glass, which weighs about 445 lb before gravel, rock and the tank itself. Fresh water weighs 8.345 lb per gallon. The weight and floor-load rows in the tool help when the tank sits on an upper floor.
Oil and Fuel Tank Volume
Heating oil tanks are often oval, with flat sides and round ends. In the Tank Volume Calculator, use the Oval (Obround) shape. A common oval tank about 27 in wide, 44 in tall and 60 in long holds about 268 US gallons (1,014 liters) brim full, a little under the 275 gallons such tanks are often sold as.
Fuel weighs less than water. With diesel at a specific gravity of 0.833, a gallon weighs about 6.95 lb, so 250 gallons is about 1,740 lb. The calculator lists common fuels and also takes a custom specific gravity.
Never fill a fuel tank to the brim. Liquids expand as they warm, so the tool warns when less than 5% of the volume is left as headspace. Follow the fill limit on the tank label.
For water held in pipes rather than a tank, the pipe volume calculator works out the volume from size and length. For pump flow rates, the gallons per minute calculator and the liters per minute calculator give the rate to enter in the pump field.
Tank Volume for Common Jobs
Homeowners checking a water tank, fish keepers buying a stand and fuel buyers reading a gauge all need a different figure from the same tank. The figure each of them needs comes from the same few measurements, worked through here for the most common sizes.
How do you calculate tank volume?
Measure the inside of the tank, then use the formula for its shape. For a box, multiply length, width and height. For a round tank standing up, multiply 3.1416 by the radius squared and by the height. Convert cubic inches to US gallons by dividing by 231, or cubic centimeters to liters by dividing by 1,000.
How many litres is a 60x30x30 tank?
A tank 60 cm long, 30 cm wide and 30 cm tall holds 60 × 30 × 30 = 54,000 cm3, which is 54 liters or 14.3 US gallons. With 4 mm glass the inside drops to about 59.2 × 29.2 × 29.6 cm, or about 51 liters.
What is the water capacity of a 15*15*15 water tank?
In feet, a 15 × 15 × 15 tank holds 3,375 cubic feet. That is about 95,570 liters or 25,250 US gallons. Leave a few inches of freeboard below an overflow, so the usable volume is a little lower.
What is the water tank capacity of an 8*6*6 water tank?
An 8 × 6 × 6 ft tank holds 288 cubic feet, about 8,155 liters or 2,154 US gallons. If the 6 ft is the height and you keep 6 in of freeboard, the usable water is about 7,475 liters.
How do you calculate the volume of a cylinder tank?
Square the inside radius, multiply by 3.1416 and then by the height or length. A 4 ft diameter tank 6 ft tall holds 3.1416 × 22 × 6 = 75.4 cubic feet, or about 564 US gallons. Lying on its side, the full volume is the same, but partial readings need the segment table above.
How do you find the volume of liquid in a partly full tank?
Measure the liquid depth from the inside bottom. In a vertical cylinder or box, multiply the floor area by that depth. For any other shape, enter the depth in the Tank Volume Calculator, which applies the segment, cap or cone formula and shows the result in gallons and liters.
How many gallons are in a cubic foot?
One cubic foot holds 7.48 US gallons, or 28.32 liters. One cubic meter holds 1,000 liters, which is about 264.2 US gallons or 35.3 cubic feet.
How do you work out the fill depth for a set volume?
Switch Solve For to Fill Depth from Volume and enter the target. For a 62.7 gallon vertical tank 32 in tall, 20 gallons sits at 10.2 in. In a horizontal or domed tank the depth is found by trial on the shape formula, which the calculator does in one step.
How long does it take to fill a tank?
Divide the tank volume by the flow rate. A 500 gallon tank on a 10 GPM hose takes 50 minutes, while a 5,000 liter tank on a 30 L/min pump takes about 2 hours 47 minutes. The calculator gives fill time from empty, top-up time from the current level and drain time.
Is there a tank volume calculator app?
The Tank Volume Calculator runs in any phone browser, with no install, and works in both US and metric units. Save the page to your home screen to open it like an app at the tank site.