Pool Fill Time Calculator for 18x18 ft Above-Ground Pool
Common 18-foot round above-ground pool approximated as square dimensions, filled with a slower garden hose.
Estimate how long it will take to fill a rectangular swimming pool based on dimensions and water flow rate. Enter your Pool Length, Pool Width, Average Depth, Hose/Water Flow Rate to get an instant estimated fill time. Formula: (length * width * averageDepth * 7.48052) / flowRate.
Estimated Fill Time
Fill in the fields above and click Calculate
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Formula
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How It Works
How It Works
This calculator estimates how long it will take to fill a rectangular swimming pool based on its size and your hose’s water flow rate. It first calculates the pool’s total water volume, then determines how many minutes are needed to fill that volume at your given flow rate.
- Multiply length × width × average depth to get volume in cubic feet.
- Convert cubic feet to gallons using 7.48052 gallons per cubic foot.
- Divide total gallons by the hose flow rate (gallons per minute).
- The result is the total fill time in minutes.
Understanding the Results
The result shows the estimated number of minutes required to completely fill your pool. This assumes a steady water flow with no interruptions or pressure changes.
- The output is given in total minutes.
- Higher flow rates reduce the fill time.
- Larger pools increase the fill time.
- For hours, divide the result by 60.
Frequently Asked Questions
How does the Pool Fill Time Calculator work?
The calculator first determines the pool’s volume in cubic feet by multiplying the length, width, and average depth. It then converts that volume to gallons using the standard conversion factor of 7.48052 gallons per cubic foot. Finally, it divides the total gallons by your hose’s flow rate (in gallons per minute) to estimate the total fill time in minutes.
When should I use this calculator?
Use this calculator when filling a new pool, refilling after maintenance, or estimating water delivery times. It helps you plan ahead for water usage and scheduling. It’s especially useful for homeowners who want to avoid overflows or manage water costs.
How do I find my hose or water flow rate?
You can measure flow rate by timing how long it takes to fill a container of known volume, such as a 5-gallon bucket. Divide the number of gallons by the time in minutes to calculate gallons per minute (GPM). Many outdoor hoses typically deliver between 5 and 12 gallons per minute, depending on water pressure.
What does average depth mean and how do I calculate it?
Average depth is the mean depth of your pool from shallow end to deep end. To calculate it, add the shallow depth and deep depth together, then divide by two. This provides a reasonable estimate for rectangular pools with a gradual slope.
Why is my actual fill time different from the estimate?
Actual fill time may vary due to changes in water pressure, hose diameter, or interruptions in flow. The calculator assumes a constant flow rate throughout the entire filling process. Minor differences are normal, especially if water pressure fluctuates during the day.
Can I use this calculator for irregularly shaped pools?
This calculator is designed specifically for rectangular pools. For irregular shapes, you would need to estimate the equivalent rectangular volume or break the pool into sections and calculate each separately. Using accurate dimensions will provide the most reliable estimate.
Disclaimer
This calculator provides estimates for informational purposes only. It is not professional advice. Verify results with a qualified professional. Disclaimer.