Cylinder Volume in Gallons Calculator
Calculate liquid storage capacity for cylindrical tanks in US gallons. One US liquid gallon equals exactly 231 cubic inches or approximately 0.13368 cubic feet. This tool is designed for sizing water heaters, livestock waterers, rainwater cisterns, agricultural fertilizer tanks, and chemical holding drums. Enter tank radius or diameter and height below to calculate total fluid gallons.
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Calculating cylindrical tank liquid capacity in US gallons
In North America, liquid holding vessels and fluid dispensing systems are universally sized and sold by their gallon capacity. Whether ordering a domestic hot water tank, installing a vertical farm cistern, or calculating swimming pool chemical dosage, gallon volume is the primary metric required.
Because liquids conform perfectly to the interior envelope of a container, calculating gallon capacity depends solely on the internal diameter and depth of the cylinder.
The cubic inch to US gallon formula explained
In the United States legal measurement system, one liquid gallon is defined as exactly 231 cubic inches. Use these mathematical equations to calculate liquid capacity in gallons:
From Inches (Radius): Gallons = (π × r² × h) ÷ 231 (where radius r and height h are in inches).
From Inches (Diameter): Gallons = (π × d² × h) ÷ 924 ≈ 0.003401 × d² × h (where diameter d and height h are in inches).
From Feet (Radius): Gallons = (π × r² × h) × 7.48052 (where radius r and height h are in feet).
From Feet (Diameter): Gallons = (π / 4) × d² × h × 7.48052 ≈ 5.875 × d² × h (where diameter d and height h are in feet).
Standard residential and commercial tank sizes reference table
The reference table below shows common residential, agricultural, and industrial cylindrical storage tank dimensions alongside their holding volume in US gallons and filled water weight:
| Tank Application Description | Diameter (in) | Height (in) | Volume (cu inches) | Total US Gallons | Filled Water Weight (lbs) |
|---|---|---|---|---|---|
| Standard 40-Gal Water Heater | 18.0 in | 36.0 in | 9,160.9 in³ | 39.66 gal | 330.8 lbs |
| Standard 50-Gal Water Heater | 20.0 in | 38.0 in | 11,938.1 in³ | 51.68 gal | 431.0 lbs |
| 55-Gallon Heavy Steel Drum | 22.5 in | 33.5 in | 13,319.4 in³ | 57.66 gal | 480.9 lbs |
| 100-Gallon Round Stock Tank | 36.0 in | 24.0 in | 24,429.0 in³ | 105.75 gal | 882.0 lbs |
| 250-Gallon Vertical Water Cistern | 36.0 in | 58.0 in | 59,036.8 in³ | 255.57 gal | 2,131.5 lbs |
| 500-Gallon Farm Fertilizer Tank | 48.0 in | 66.0 in | 119,428.2 in³ | 517.00 gal | 4,311.8 lbs |
| 1,000-Gallon Rainwater Cistern | 64.0 in | 72.0 in | 231,623.5 in³ | 1,002.70 gal | 8,362.5 lbs |
| 2,500-Gallon Heavy Storage Tank | 90.0 in | 92.0 in | 585,278.7 in³ | 2,533.67 gal | 21,130.8 lbs |
Estimating liquid weight and slab load requirements
When installing large cylindrical water tanks or chemical vessels, calculating structural foundation loading is essential. Pure water weighs exactly 8.34 pounds per US gallon (1.0 kg per liter).
A 500-gallon water storage tank holds 4,170 pounds (over two tons) of water when filled. Concrete slabs, wooden decks, and tank support stands must be engineered to carry this concentrated downward point load safely.
Cross unit decision guidance and solid material tools
If your project involves solid materials, concrete columns, soil excavation, or grain storage, use our specialized Cylinder Volume in Cubic Feet Calculator. For an industry comparison of when to specify tanks in gallons versus cubic feet, read our Cylinder Capacity Gallons and Cubic Feet Guide.
Rainwater harvesting cistern sizing in gallons
Residential and agricultural rainwater collection systems are sized based on roof catchment area and cylindrical cistern holding capacity in US gallons.
As a general rule, one inch of rainfall on a 1,000 square foot roof yields approximately 623 gallons of harvestable water. A cylindrical cistern measuring 8 feet in diameter (96 inches) and 8 feet in height (96 inches) holds: V = (π × 48² × 96) ÷ 231 = 3,008.2 US gallons.
Sizing your cylindrical holding tank to match local seasonal rainfall patterns ensures sufficient water reserve throughout dry summer months.
For multi-unit liquid conversions across US gallons, imperial gallons, barrels, and liters, consult our volume unit conversion guide.
Frequently Asked Questions
How do I calculate gallons in a cylinder from inches?
Calculate volume in cubic inches with V = π × r² × h, then divide the result by 231. There are exactly 231 cubic inches in 1 US liquid gallon.
How do I calculate gallons in a cylinder from feet?
Calculate volume in cubic feet with V = π × r² × h, then multiply by 7.48052. One cubic foot holds approximately 7.48 US liquid gallons.
How much does a 55-gallon drum of water weigh?
A filled 55-gallon water drum contains approximately 459 pounds (208 kg) of water, plus the 40 to 50 pound tare weight of the steel drum.
What is the difference between US liquid gallons and UK gallons?
A US liquid gallon equals 231 cubic inches (3.785 L). A UK imperial gallon equals 277.42 cubic inches (4.546 L), making it 20.09% larger than a US gallon.
How do I calculate gallons for a partially filled horizontal cylinder?
Use our dedicated horizontal tank calculator to compute the circular segment area of the fluid depth and multiply by the length.