Pool Volume Calculator
Calculate the water volume of a swimming pool in gallons and liters based on pool dimensions and shape to properly dose chemicals, size equipment, and estimate fill costs.
This free online pool volume calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
Range: 5 – 100
Length of the pool.
Range: 3 – 50
Width of the pool.
Range: 1 – 15
Average depth. For sloped pools, average the shallow and deep ends.
Non-rectangular pools hold less water than L x W x D suggests.
Results
Volume
2250 cu ft
Volume
16832 gallons
Volume
63710 liters
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Pool Volume Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Pool Volume Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
When to Use This Calculator
- •Use the Pool Volume Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
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About Pool Volume Calculator
Knowing the exact volume of water in your swimming pool is essential for proper chemical dosing, equipment sizing, heating calculations, and estimating water fill costs. Over-dosing chemicals wastes money and can make the water uncomfortable, while under-dosing leads to algae growth and unsafe bacteria levels. This calculator converts your pool dimensions into gallons using shape-specific multipliers: rectangular pools use the full length-times-width-times-depth formula, while oval and circular pools apply correction factors that account for their curved geometry. The average depth is the most critical input for pools with sloped bottoms: measure the shallow end depth and deep end depth, then average them. For pools with a distinct breakpoint between shallow and deep sections, treat each section as a separate rectangular volume and add them together for more accuracy.
The Math Behind It
Formula Reference
Pool Volume Formula
Volume = L x W x Avg Depth x Shape Factor x 7.481 gal/cu ft
Variables: L, W, Depth in feet; Shape Factor: 1.0 for rectangle, 0.89 for oval, 0.785 for round.
Worked Examples
Example 1: Standard rectangular pool
30 ft long, 15 ft wide, average depth 5 ft, rectangular shape.
The pool holds approximately 16,832 gallons (63,711 liters) of water.
Example 2: Kidney-shaped pool
25 ft long, 12 ft wide at widest, average depth 4.5 ft, oval/kidney shape.
The kidney pool holds approximately 8,988 gallons.
Common Mistakes & Tips
- !Using the deep end depth instead of the average depth, which overestimates volume by 30-50 percent for pools that slope from shallow to deep.
- !Forgetting the shape correction factor for oval and circular pools, which overestimates volume by 11-22 percent.
- !Not accounting for the coping and tile line -- the pool is not filled to the absolute top, so subtract 4-6 inches from the wall height for the usable water depth.
Related Concepts
Frequently Asked Questions
How much does it cost to fill a pool?
Municipal water costs $5-15 per 1,000 gallons in most US cities, so filling a 20,000-gallon pool costs $100-300 from a garden hose. Water delivery by tanker truck costs $200-600 for a full pool, depending on distance and local rates. Well water is free (minus electricity for the pump) but filling a pool can temporarily deplete the well, especially in summer. A garden hose typically delivers 5-10 gallons per minute, meaning a 20,000-gallon pool takes 33-67 hours to fill.
Why do I need to know my pool volume?
Pool volume is required for every chemical calculation: chlorine, pH adjustment, algaecide, calcium hardness, and stabilizer are all dosed based on gallons. Using the wrong volume leads to incorrect chemical levels that are either ineffective or dangerous. Volume is also needed for sizing filtration pumps (the pump should turn over the entire pool volume every 6-8 hours), selecting heaters (BTU requirements depend on gallons), and calculating evaporation and water loss rates.
How do I measure the average depth of my pool?
For a uniformly sloped pool, measure the depth at the shallowest point and the deepest point, then average them: (shallow + deep) / 2. For pools with a distinct shallow end and deep end separated by a breakpoint, calculate each section separately and add the volumes. Use a pool pole with depth markings or a weighted measuring tape lowered to the bottom at several points to get accurate depth readings.
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