Pool Fill Time Calculator
Estimation Results
Total Estimated Volume: Gallons
Total Fill Time:
*Estimates are based on consistent water pressure and standard cubic foot to gallon conversions.
How to Calculate Pool Fill Time
Filling a pool is a test of patience, but knowing exactly how long it will take helps you plan your maintenance and chemical balancing schedule. The calculation involves two primary steps: determining the total volume of the pool in gallons and measuring the flow rate of your water source.
1. Calculating Pool Volume
The math changes slightly based on the shape of your pool. We use the multiplier 7.48, which is the number of gallons in one cubic foot of water.
- Rectangular: Length × Width × Average Depth × 7.48
- Round: π × Radius² × Average Depth × 7.48
- Oval: Length × Width × Average Depth × 5.9 (A simplified constant for oval volume)
2. Determining Flow Rate
Most residential garden hoses deliver between 5 and 12 gallons per minute (GPM). To find your exact flow rate, time how long it takes to fill a 5-gallon bucket with your hose at full blast. Divide 5 by the number of minutes it took. For example, if it takes 30 seconds (0.5 minutes), your flow rate is 10 GPM.
Realistic Examples
Example 1: Standard Backyard Pool
A 15ft x 30ft rectangular pool with an average depth of 4.5ft holds approximately 15,147 gallons. With a standard 9 GPM hose, it will take roughly 28 hours to fill.
Example 2: Small Above-Ground Round Pool
An 18ft diameter round pool with a 4ft depth holds about 7,600 gallons. At 9 GPM, this takes about 14 hours.
Tips to Speed Up the Process
If you find that your fill time is stretching into multiple days, consider these options:
- Use Multiple Hoses: If you have multiple outdoor spigots on different lines, using two hoses will cut your fill time in half.
- Water Delivery Service: For very large pools, hiring a water truck is much faster, though significantly more expensive.
- Check Pressure: Ensure no other major water appliances (washing machine, irrigation) are running during the fill to maintain maximum flow.