Calculate volume of liquid for a given area and depth
Updated March 2025
Total Gallons
623.38
Total Liters
2,359.74
Cubic Volume
83.33 ft³
Volume calculation determines how much liquid or material a three-dimensional space can hold. For a rectangular area with uniform depth, volume is calculated as Area × Depth. This is essential for applications like calculating water volume in pools, raindrop collection, irrigation requirements, paint coverage, flooring materials, and chemical treatment dosages.
Important: Despite its name, this calculator computes total volume from area and depth—not a per-unit rate. The historical "gallons per square foot" refers to the volume of 1 inch of liquid spread uniformly (≈ 0.62 gallons). This tool calculates how many gallons or liters fill a space of specified area and depth.
This calculator converts between multiple volume units: gallons, liters, and cubic feet or meters. It's commonly used by contractors for concrete/paint coverage, landscapers for water requirements, pool builders for capacity, and engineers for storage tank sizing or fluid management calculations. Metric mode correctly uses cubic meters to liters conversion.
Step 1: Measure the Area
Determine the base area in square feet or square meters. For rectangular areas: width × length. For irregular shapes, divide into rectangles and sum. For circular areas: π × r².
Step 2: Measure the Depth
Measure the uniform depth or height in inches (imperial) or centimeters (metric). For varying depths (like sloped pools), use the average depth: (shallow end + deep end) ÷ 2.
Step 3: Calculate Cubic Volume
Cubic Volume = Area × Depth. This gives you cubic feet (imperial) or cubic meters (metric). This is the universal volume unit before converting to gallons or liters.
Step 4: Convert to Desired Units
Multiply cubic volume by conversion factors: cubic feet × 7.48 = gallons, cubic meters × 264 = gallons, or cubic meters × 1000 = liters. Use this for purchasing, planning, or specification purposes.
Step 5: Account for Actual Capacity
Real containers rarely hold 100% of calculated volume due to rim height, slope, or settling. Multiply calculated total by 0.85-0.95 for actual usable capacity. Always round up for ordering materials.
Conversion Reference
Scenario: You want to install a rectangular above-ground pool measuring 20 ft long, 15 ft wide, and 4 ft deep. Calculate total volume in gallons and liters.
Given:
Calculation:
Practical Application:
How many gallons per inch of depth?
For any area, multiply square footage by 0.62. For 1,000 sq ft, 1 inch depth = 623 gallons. This is why rain falls so quickly into buckets and pools fill from rainfall!
What about irregular shaped areas?
Divide the irregular shape into smaller rectangles, calculate each volume separately, and add them together. For circular areas, use Area = π × r². For triangular: Area = ½ × base × height.
Why can't my container hold the calculated volume?
Containers have rim, sloped sides, or settling factors. Real capacity is typically 85-95% of calculated. For safety, always order 5-10% extra materials. Also account for soil settling in landscaping applications.
How is this used for concrete coverage?
Concrete is ordered by cubic yards (27 cubic feet = 1 yard). Height is typically measured in inches. For a 4-inch slab: cubic feet ÷ 27 = cubic yards needed. Most concrete bags cover ~0.5 sq ft at 4" depth.
What about water tank sizing?
Tanks hold specific volumes (55 gallons per cubic foot). Calculate your volume need, divide by tank size, and round up. A 1,000 gallon tank stores ~133 cubic feet. Most residential tanks are 500-1000 gallons.
How do I calculate for sloped areas?
Use the average depth across the slope. For a floor sloping from 1 inch to 3 inches deep: average = 2 inches. Calculate total volume using this average depth. For complex slopes, divide into sections with uniform slope.
What's the difference between gallons and liters?
1 gallon = 3.785 liters (US gallon). 1 cubic foot = 7.48 gallons. 1 cubic meter = 1,000 liters. Always check which measurement system your materials/resources use (US vs. metric).
How do I estimate gravel or mulch coverage?
Gravel/mulch is sold by cubic yard. Calculate total cubic feet, divide by 27 for cubic yards, then round up. Typical coverage: 3-4" depth of mulch per cubic yard covers 75-100 sq ft. Gravel density varies 1.3-1.5 tons/yard.
Disclaimer: Volume calculations assume flat, uniform surfaces. Actual surface slopes, irregularities, and settling affect material needs. This calculator provides estimates for planning purposes. Order 10-15% extra material to account for waste, spillage, and settling. Always verify project requirements with your supplier before ordering. Actual coverage varies by material type, density, and application method.
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