How does the fill depth work?

The tank is a cylinder on its side, and the fill depth is how high the liquid stands, measured up from the bottom of the tank. 0 is empty, and the full diameter is a full tank; a depth greater than the diameter is refused with a message saying what the tank's depth is. The tool works out the area of the circular segment the liquid covers, r² acos((r − f)/r) − (r − f) √(2rf − f²), and multiplies it by the length.

Why is a quarter of the depth not a quarter of the volume?

Because a circle is narrow at the bottom and widest in the middle. A tank of radius 1 m and length 2 m holds 6.283 m³ full and exactly half that, 3.142 m³, at 1 m of depth; at 0.5 m, a quarter of the way up, it holds 1.228 m³, which is 19.6% of the tank, not 25%. The stage says what percentage of the full tank the fill depth holds, and the When full row gives the capacity.

What about a vertical tank, standing on its end?

Pick Cylinder instead. A vertical tank's liquid is a shorter cylinder, so type the tank's radius or diameter and the depth of the liquid as the height, and the answer is the liquid's volume. Type the tank's full height for its capacity.

Should I measure the radius or the diameter?

Whichever is easier. The diameter is the full width across the end, which is what a tape measure gives you; the switch beside the field takes either and halves a diameter before it goes into the formula, and the formula line says r = d/2 when it did. Use the inside measurement for the liquid, since the wall takes up space.

How many litres or gallons is that?

The rows under the answer give litres, US gallons and UK gallons every time, whichever unit you measured in, plus cubic units for the scale you used. A US gallon is 231 cubic inches, which is 3.785411784 litres, and a UK gallon is 4.54609 litres; a 1,000 litre tank is 264 US gallons or 220 UK gallons.

How are measurements, units and saved work handled?

Choose the measured unit before typing; changing it reinterprets bare numbers rather than converting them. Decimal and scientific numbers, complete comma groups such as 1,200, numeric fractions such as 3/4 and mixed numbers such as 2 1/2 are accepted; written unit suffixes and expressions are not. Switching radius and diameter converts the current measurement to preserve the shape. Saved strings restore without writing defaults. Deliberate edits preserve independent newer saved fields, and malformed records are left intact. Results, full tank capacity and conversions must fit the supported numeric range. The visible result summary is selectable if the clipboard is unavailable.

Tank Volume Calculator

Type a horizontal tank's radius or diameter, its length and the liquid's depth, and read how much it holds in litres and gallons, plus its full capacity. The partial fill uses the circular-segment model, with stable arithmetic near empty and full, and the formula is shown with the working under it.

Cylinder · π r² h0.942478m³942.478 L · 248.976 US gal · 207.316 UK gal

Shape

Measure

Radius (m)

Height (m)

Unit

A drum, can or straight pipe: use the inner radius or diameter for capacity. Height is perpendicular to the circular end, including for an oblique cylinder; it is not a slanted axis length. The drawing is schematic. Choose the measured unit before typing; changing it reinterprets the numbers.

Result summary

Cylinder, radius 0.5 m, height 1.2 m
0.942477796077 m³
The working: π × 0.5² × 1.2 = 0.942477796077 volume, in m³
Litres: 942.477796077 L
US gallons: 248.976293692 US gal
UK gallons: 207.316132342 UK gal
Cubic feet: 33.2832892609 ft³
Cubic yards: 1.23271441707 yd³
Cubic inches: 57,513.5238428 in³

The workingvolume, in m³
π × 0.5² × 1.2 = 0.942477796077
LitresL
942.477796077
US gallonsUS gal
248.976293692
UK gallonsUK gal
207.316132342
Cubic feetft³
33.2832892609
Cubic yardsyd³
1.23271441707
Cubic inchesin³
57,513.5238428

The formula is on the stage, and the working is the first row. Every answer here is one textbook formula with your numbers put in, printed so you can check it: a cylinder is π r² h, a sphere is (4/3) π r³, a pool is length times width times the average of its two depths. The horizontal tank uses the circular-segment model with stable arithmetic for a partial fill, so half way up is exactly half and a quarter of the way up is less than a quarter, because the bottom of a circle is narrow. Conversions use exact definitions: a litre is 1,000 cm³, a US gallon is 231 cubic inches and a UK gallon is 4.54609 litres. Results are rounded; drawings are schematic. No arbitrary outlines, end caps, tapered tanks, pressure, chemical dosing, reverse dimensions, subtraction or shared surface-area result is computed here.

Common questions

How does the fill depth work?: The tank is a cylinder on its side, and the fill depth is how high the liquid stands, measured up from the bottom of the tank. 0 is empty, and the full diameter is a full tank; a depth greater than the diameter is refused with a message saying what the tank's depth is. The tool works out the area of the circular segment the liquid covers, r² acos((r − f)/r) − (r − f) √(2rf − f²), and multiplies it by the length.
Why is a quarter of the depth not a quarter of the volume?: Because a circle is narrow at the bottom and widest in the middle. A tank of radius 1 m and length 2 m holds 6.283 m³ full and exactly half that, 3.142 m³, at 1 m of depth; at 0.5 m, a quarter of the way up, it holds 1.228 m³, which is 19.6% of the tank, not 25%. The stage says what percentage of the full tank the fill depth holds, and the When full row gives the capacity.
What about a vertical tank, standing on its end?: Pick Cylinder instead. A vertical tank's liquid is a shorter cylinder, so type the tank's radius or diameter and the depth of the liquid as the height, and the answer is the liquid's volume. Type the tank's full height for its capacity.
Should I measure the radius or the diameter?: Whichever is easier. The diameter is the full width across the end, which is what a tape measure gives you; the switch beside the field takes either and halves a diameter before it goes into the formula, and the formula line says r = d/2 when it did. Use the inside measurement for the liquid, since the wall takes up space.
How many litres or gallons is that?: The rows under the answer give litres, US gallons and UK gallons every time, whichever unit you measured in, plus cubic units for the scale you used. A US gallon is 231 cubic inches, which is 3.785411784 litres, and a UK gallon is 4.54609 litres; a 1,000 litre tank is 264 US gallons or 220 UK gallons.
How are measurements, units and saved work handled?: Choose the measured unit before typing; changing it reinterprets bare numbers rather than converting them. Decimal and scientific numbers, complete comma groups such as 1,200, numeric fractions such as 3/4 and mixed numbers such as 2 1/2 are accepted; written unit suffixes and expressions are not. Switching radius and diameter converts the current measurement to preserve the shape. Saved strings restore without writing defaults. Deliberate edits preserve independent newer saved fields, and malformed records are left intact. Results, full tank capacity and conversions must fit the supported numeric range. The visible result summary is selectable if the clipboard is unavailable.

Rounded browser arithmetic for the dimensions and ideal shapes shown; pools assume a uniform or linear depth profile. Drawings are schematic. A US gallon is 231 cubic inches and a UK gallon is 4.54609 litres.