Calculate your pool's water volume for accurate chemical dosing, fill time estimates, and heating costs. Select your pool shape and enter dimensions to get instant results.
Pool Dimensions
Pool Shape Preview
Cost Settings
Fill Time Estimate
Heating Cost Estimate
Chemical Dosing Guide
Chemical Dosing Reference for Your Pool
Based on your pool volume, here are approximate chemical amounts. Always test water first and follow manufacturer instructions.
| Chemical | Purpose | Amount Needed | Frequency |
|---|
Water Volume for Common Pool Sizes
Reference table showing approximate gallons for standard residential pool sizes at an average depth of 5 feet.
| Pool Shape | Dimensions | Avg Depth | Gallons | Liters |
|---|---|---|---|---|
| Rectangular | 12 x 24 ft | 5 ft | 10,800 | 40,880 |
| Rectangular | 14 x 28 ft | 5 ft | 14,700 | 55,640 |
| Rectangular | 16 x 32 ft | 5 ft | 19,200 | 72,670 |
| Rectangular | 18 x 36 ft | 5 ft | 24,300 | 91,960 |
| Rectangular | 20 x 40 ft | 5 ft | 30,000 | 113,560 |
| Round | 15 ft diameter | 4 ft | 5,300 | 20,060 |
| Round | 18 ft diameter | 4 ft | 7,630 | 28,880 |
| Round | 21 ft diameter | 4 ft | 10,380 | 39,290 |
| Round | 24 ft diameter | 4 ft | 13,560 | 51,330 |
| Oval | 12 x 24 ft | 4 ft | 6,790 | 25,700 |
| Oval | 15 x 30 ft | 4 ft | 10,600 | 40,120 |
| Kidney | 16 x 32 ft | 5 ft | 14,400 | 54,500 |
Pool Water Management Tips
Test Before Treating
Always test your pool water with a reliable kit or test strips before adding chemicals. Test at least 2-3 times per week during swim season and after heavy rain or high bather loads.
Use a Pool Cover
A pool cover reduces evaporation by up to 95%, cuts heating costs by 50-70%, and keeps debris out. Solar covers can warm your pool by 5-15 degrees for free using sunlight.
Maintain Proper Chemistry
Keep free chlorine at 1-3 ppm, pH between 7.2-7.6, alkalinity at 80-120 ppm, and calcium hardness at 200-400 ppm. Balanced water extends equipment life and keeps swimmers comfortable.
Account for Evaporation
Pools lose 1/4 to 1/2 inch of water per day to evaporation. In hot, dry climates, that can mean 25,000+ gallons per year. A pool cover is the most effective way to reduce water loss.
Know Your Fill Rate
Measure your actual hose flow rate by timing how long it takes to fill a 5-gallon bucket. Standard garden hoses deliver 6-12 GPM depending on hose diameter and water pressure.
Optimize Heating
Heat your pool during off-peak electricity hours. A heat pump is 3-5x more energy efficient than a gas heater for maintaining temperature. Gas heaters are better for quick heat-ups.
How Pool Volume is Calculated
Pool volume is calculated using geometric formulas based on the pool shape and dimensions. The average depth is the midpoint between the shallow and deep ends, accounting for the sloped floor.
Rectangular pools: Length × Width × Average Depth × 7.48 = gallons. The multiplier 7.48 converts cubic feet to US gallons (1 cubic foot = 7.48052 gallons).
Round pools: π × Radius² × Average Depth × 7.48 = gallons. The radius is half the diameter. This is the standard formula for the volume of a cylinder.
Oval pools: π × (Length/2) × (Width/2) × Average Depth × 7.48 = gallons. An oval is treated as an ellipse, so we use half the length and half the width as the two radii.
Kidney / Irregular pools: Length × Width × Average Depth × 0.45 × 7.48 = gallons. The 0.45 multiplier approximates the curved, irregular shape. This provides a reasonable estimate, but actual volume may vary by 5-15% depending on the exact shape.
Fill time is calculated by dividing the total gallons by the hose flow rate in gallons per minute. Fill cost uses your local water rate per 1,000 gallons. Heating cost uses the formula: gallons × 8.33 lbs/gal × temperature rise ÷ 100,000 BTU/therm × cost per therm ÷ heater efficiency (80%).
Frequently Asked Questions
How do I calculate the volume of my pool?
Multiply length × width × average depth to get cubic feet, then multiply by 7.48 to convert to gallons. For round pools, use π × radius² × average depth. Average depth is calculated as (shallow end + deep end) ÷ 2 for pools with a sloped floor. For irregularly shaped pools like kidney shapes, multiply the rectangular volume by 0.45 to approximate the curved area.
How many gallons of water does a typical pool hold?
A typical residential pool holds 10,000 to 30,000 gallons. A small 12×24 ft pool with 5 ft average depth holds about 10,800 gallons. A mid-size 16×32 ft pool holds about 19,200 gallons. A large 20×40 ft pool holds about 30,000 gallons. Above-ground round pools are typically 5,000-15,000 gallons depending on diameter and depth.
How long does it take to fill a pool with a garden hose?
A standard 5/8-inch garden hose delivers about 9 gallons per minute (540 GPH). At this rate, a 15,000-gallon pool takes about 28 hours to fill. Using two hoses cuts the time in half. A larger 1-inch hose can deliver 15+ GPM. Actual flow rate depends on your water pressure, hose length, and diameter.
How much does it cost to fill a pool with water?
Water costs vary by region but average $4-$10 per 1,000 gallons. A 20,000-gallon pool costs roughly $80-$200 to fill. Some water utilities offer pool fill rate discounts or sewer exemptions since pool fill water does not enter the sewer system. Contact your local utility to ask about special rates.
How much chlorine do I need for my pool?
To raise free chlorine by 1 ppm, you need about 2 fluid ounces of liquid chlorine (12.5% sodium hypochlorite) per 1,000 gallons. Most pools should maintain 1-3 ppm free chlorine. For shock treatment (raising to 10+ ppm), use about 1 pound of calcium hypochlorite (cal-hypo) granular shock per 10,000 gallons. Always test before and after adding chemicals.
How much does it cost to heat a swimming pool?
Heating costs depend on pool size, desired temperature rise, and heater type. A gas heater costs roughly $3-$7 per hour for a 400,000 BTU unit. To raise a 20,000-gallon pool by 10 degrees F costs approximately $25-$50 in natural gas. Heat pumps are 3-5x more efficient but heat more slowly. A solar pool cover can reduce heating costs by 50-70%.
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Pool Volume Calculator FAQ
How do I calculate the volume of my pool?
Multiply length x width x average depth to get cubic feet, then multiply by 7.48 to convert to gallons. For round pools, use the formula: pi x radius squared x average depth. Average depth is calculated as (shallow end + deep end) / 2 for pools with a slope.
How many gallons of water does a typical pool hold?
A typical residential pool holds 10,000 to 30,000 gallons. A small 12x24 ft pool averages about 8,600 gallons, a mid-size 16x32 ft pool holds about 19,200 gallons, and a large 20x40 ft pool holds about 30,000 gallons. The exact volume depends on the pool shape and depth.
How long does it take to fill a pool with a garden hose?
A standard garden hose delivers about 9 gallons per minute (540 gallons per hour). At this rate, a 15,000-gallon pool takes about 28 hours to fill. A larger 1-inch hose can deliver 12-15 GPM, cutting fill time significantly. Some homeowners use a fire hydrant permit for much faster filling.
How much does it cost to fill a pool with water?
The average cost to fill a pool is $4 to $10 per 1,000 gallons of water, depending on your local water rates. A 20,000-gallon pool costs roughly $80 to $200 to fill. Some areas charge additional sewer fees on water usage, so check with your utility company about pool fill exemptions.
How much chlorine do I need for my pool?
As a general rule, you need about 2 ounces of liquid chlorine (sodium hypochlorite 12.5%) or 0.5 ounces of granular chlorine per 1,000 gallons to raise the chlorine level by 1 ppm. Most pools should maintain 1-3 ppm free chlorine. Always test your water before adding chemicals and follow manufacturer directions.
How much does it cost to heat a swimming pool?
Heating a pool costs $3 to $7 per hour for a gas heater or $1 to $3 per hour for a heat pump, depending on pool size and desired temperature. Monthly heating costs range from $100 to $600. Solar pool covers can reduce heating costs by 50-70% by preventing overnight heat loss.