About

Miscalculating a cylindrical tank's capacity leads to overfilling, material waste, or undersized storage. This calculator computes the exact volume of any right circular cylinder using the standard geometric formula V = π ⋅ r² ⋅ h, then converts the result into US gallons (231 in³ per gallon), Imperial gallons (277.42 in³ per gallon), and liters. It handles partial fill percentages and estimates the weight of water at standard density of 8.345 lb/US gal. Results assume a perfect right circular cylinder. Real tanks with dished heads, baffles, or irregular geometry will deviate. For pressurized vessels or ASME-rated tanks, consult engineering drawings for true internal volume.

Formulas

The volume of a right circular cylinder is derived from the area of its circular cross-section multiplied by its height.

V = π ⋅ r² ⋅ h

Since inputs commonly use diameter rather than radius:

V = π ⋅ d²4 ⋅ h

Conversion to US gallons uses the exact legal definition:

V_gal(US) = V_in³231

For Imperial gallons:

V_gal(Imp) = V_in³277.42

For liters:

V_L = V_in³61.024

Partial fill volume scales linearly for a vertical cylinder:

V_fill = V_total × F100

Water weight estimate at 60°F:

W_lb = V_gal(US) × 8.345 lb/gal

Where d = diameter, r = radius (d ÷ 2), h = height/length of the cylinder, F = fill percentage (0 - 100), and all linear measurements are normalized to inches before calculation.

Reference Data

Tank Diameter	Tank Height	Volume (US gal)	Volume (Imp gal)	Volume (L)	Water Weight (lb)
12 in	24 in	11.76	9.79	44.52	98.14
18 in	36 in	39.69	33.05	150.24	331.21
24 in	48 in	94.07	78.32	356.12	784.90
30 in	48 in	146.98	122.38	556.44	1226.39
36 in	60 in	264.57	220.29	1001.58	2207.84
48 in	72 in	564.08	469.66	2135.50	4706.23
1 ft	2 ft	11.76	9.79	44.52	98.14
2 ft	4 ft	94.07	78.32	356.12	784.90
3 ft	5 ft	264.57	220.29	1001.58	2207.84
4 ft	6 ft	564.08	469.66	2135.50	4706.23
5 ft	8 ft	1175.17	978.46	4449.00	9806.04
6 ft	10 ft	2116.56	1762.31	8012.64	17,658.68
30 cm	60 cm	11.12	9.26	42.41	92.82
50 cm	100 cm	51.85	43.16	196.35	432.68
1 m	2 m	414.80	345.32	1570.80	3461.44

Frequently Asked Questions

A US liquid gallon equals exactly 231 cubic inches (3.78541 liters), while an Imperial gallon equals approximately 277.42 cubic inches (4.54609 liters). The Imperial gallon is about 20% larger. This calculator reports both to prevent errors when sourcing tanks from different markets. Always verify which gallon standard your tank manufacturer uses.

No. This calculator assumes a vertical (upright) cylinder where partial fill scales linearly with height. For a horizontal cylinder, the filled volume involves a circular segment integral and is nonlinear - a 50% height fill does not equal 50% volume. Use a dedicated horizontal tank calculator for that geometry.

The weight uses a density of 8.345 lb per US gallon, which corresponds to water at approximately 60°F (15.6°C). Water density varies with temperature: at 40°F it is about 8.345 lb/gal, at 100°F about 8.288 lb/gal, and at 200°F about 8.04 lb/gal. For hot water tanks or industrial processes at elevated temperatures, apply a correction factor of roughly −0.03 lb/gal per 10°F above 60°F.

This tool calculates geometric volume based on the dimensions you enter. If you enter the outer diameter, you will overestimate internal capacity. For steel tanks, subtract twice the wall thickness from the outer diameter to get the inner diameter. Common steel tank walls range from 3/16 inch (4.8 mm) to 1/2 inch (12.7 mm) depending on pressure rating.

The volume results (gallons, liters) apply to any liquid since volume is geometry-dependent, not substance-dependent. However, the weight output assumes water density. For other liquids, multiply the volume by the liquid's specific gravity. Diesel fuel has a specific gravity of approximately 0.85, gasoline about 0.74, and milk about 1.03.

For tanks measured in feet, select the feet unit. The calculator handles all conversions internally. A common industrial tank of 10 ft diameter × 20 ft height holds approximately 11,752 US gallons. For metric installations, use meters. Avoid mixing units between diameter and height - both must use the same unit selection.