How do I calculate the volume of a cylindrical tank?

Multiply the circle area of the end by the tank length. For a vertical tank that end is the base and the length is the height; for a horizontal tank the end is the circular face and the length runs along the ground. A tank 4 feet across and 6 feet long holds about 564 gallons. This tool does both orientations in gallons and litres.

How do I work out a part-full horizontal tank?

A lying-down cylinder is the hard one, because the fluid makes a circular segment, not a neat fraction of the circle. Enter a fill depth and the tool uses the segment-area formula to find exactly how much is in there — that is why a horizontal tank half full by depth really is half full, but a third full by depth is not a third of the volume.

Does this handle tank ends and dished heads?

No — it treats the tank as a plain cylinder. Real tanks often have domed or dished ends that add a little capacity, and a stand or sump changes the usable amount. Take the cylinder figure as the body volume and add or trust the maker for the ends.

Tank volume calculator

Orientación

Diámetro

Altura / largo

Nivel de llenado (opcional)

Déjelo en blanco para el tanque lleno.

— gal, tanque lleno

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This models the tank as a plain cylinder. Dished ends, internal baffles, a sloped base or a standpipe all shift the true capacity, so use the figure for planning a fill or a haul and trust the tank's own gauge for anything that must be exact.

Pick whether the tank stands up or lies on its side, enter the diameter and the length, and read the full volume in gallons and litres. Add a fill depth and the tool works out how much is actually in a part-full tank — the tricky case when it is lying down.

Ejemplo resuelto

A tank 4 ft across is π × 2² ≈ 12.57 sq ft on the end. Six feet long that is 75.4 cubic feet, about 564 gallons or 2135 litres. Lay it down and fill it to 1 foot deep and the segment maths gives roughly 110 gallons — under a fifth, because the bottom of a round tank is narrow.

In metric: a tank 1.2 m across is π × 0.6² ≈ 1.131 m² on the end. Two metres long that is 2.262 m³, or 2,262 litres (598 US gallons). On its side and dipped at 0.3 m — a quarter of the diameter — it holds 19.6% of that, about 442 litres.

En la obra

Dipping a fuel tank. A horizontal tank 48 in across and 130 in long is 1,020 gallons full. The stick comes out wet to 12 in — a quarter of the diameter, but not a quarter of the fuel. The segment under a 12 in chord in a 48 in circle is 19.6% of the end, so the tank holds about 200 gallons, and the delivery you can take is 820, not 765. At 24 in it really is half; at 36 in it is 80.4%. Put the tank in as horizontal with a 1 ft fill depth and the tool does the segment.

Sizing a pump-out. A 3 ft round sump 4 ft deep is π × 1.5² × 4 = 28.3 ft³ = 211 gallons. Upright tanks are simple: the volume is proportional to the depth, so at 2 ft of water it holds 106. A pump rated 20 GPM at the head you have empties it in about ten minutes; the pump tool works the other direction.

Rain totes. An IBC is 1,000 L, which is 264 US gallons — or 220 imperial, and that distinction has cost more than one person a tank of the wrong size. This page reports US gallons and litres; if the spec is imperial, divide the US figure by 1.2.

What went wrong?

Quick referencefor tanks

Gallons per foot of length, by diameter: 1 ft 5.9 · 2 ft 23.5 · 3 ft 52.9 · 4 ft 94 · 5 ft 147 · 6 ft 211 · 8 ft 376
Shortcut: gal per ft = 5.87 × D² (D in feet)
Litres per metre of length, by diameter: 1 m 785 · 1.5 m 1,767 · 2 m 3,142 · 2.5 m 4,909 · 3 m 7,069
Metric shortcut: L per m = 785 × D² (D in metres)
Horizontal tank, by stick: ¼ depth = 19.6% · ½ = 50% · ¾ = 80.4%
Unidades: 1 ft³ = 7.48 US gal · 1 m³ = 1,000 L = 264 US gal · 1 imperial gal = 1.2 US gal
An IBC tote: 1,000 L · 264 US gal · 220 imperial gal

Mistakes to catchbefore you trust the number

Typing the outside diameter of an insulated or double-walled tank — capacity is the inside diameter.
Reading the stick on a horizontal tank as a straight percentage of height: half the height is half the volume, but a quarter of the height is well under a quarter of the volume; the tool does the segment maths.
Forgetting the dished ends on a pressure vessel, which add capacity the straight cylinder misses.

La fórmula

full = π × (D ÷ 2)² × L · segment = [r²·acos((r−h)/r) − (r−h)·√(2rh − h²)] × L

The full volume is the end circle times the length either way up. A part-full horizontal tank holds a circular segment of fluid, so the second formula finds that segment's cross-section from the fill depth h and radius r, then multiplies by the length. A vertical tank is easier — the fill is just a shorter cylinder.

Preguntas

How do I calculate the volume of a cylindrical tank?: Multiply the circle area of the end by the tank length. For a vertical tank that end is the base and the length is the height; for a horizontal tank the end is the circular face and the length runs along the ground. A tank 4 feet across and 6 feet long holds about 564 gallons. This tool does both orientations in gallons and litres.
How do I work out a part-full horizontal tank?: A lying-down cylinder is the hard one, because the fluid makes a circular segment, not a neat fraction of the circle. Enter a fill depth and the tool uses the segment-area formula to find exactly how much is in there — that is why a horizontal tank half full by depth really is half full, but a third full by depth is not a third of the volume.
Does this handle tank ends and dished heads?: No — it treats the tank as a plain cylinder. Real tanks often have domed or dished ends that add a little capacity, and a stand or sump changes the usable amount. Take the cylinder figure as the body volume and add or trust the maker for the ends.

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