Free Tool
Free pool volume calculator
Enter your pool size and average depth to get the volume in gallons, for a rectangle or a round pool. Free, no signup.
Shallow plus deep end, divided by two
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Gallons drive everything else
The volume in gallons is the number behind almost every pool decision: the pump and filter size, the heater, the turnover rate, and every dose of chemicals. Get it wrong and the water is either under-treated or you are pouring money in the pool.
The math is the surface area times the average depth times 7.48 gallons per cubic foot. Pick rectangle or round and enter the dimensions, and the calculator returns the area, the volume, and the gallons.
Average depth is the piece people miss on a pool that is not flat-bottomed. Take the shallow end depth plus the deep end depth and divide by two. A pool that slopes from 3 feet to 8 feet has an average depth of about 5.5 feet, not 8.
This is a close estimate for a simple rectangle or round pool. A kidney or freeform shape holds a bit less than the box around it, so treat the number as a slightly high starting point and trim it for the curves.
Pool Volume Calculator questions
How do I calculate pool gallons?
Surface area times average depth times 7.48. The calculator does it for a rectangle or a round pool.
What is average depth?
The shallow end depth plus the deep end depth, divided by two. Use it, not the deep end, for a sloped pool.
Why does volume matter?
It sizes the pump, filter, and heater, and it sets every chemical dose. It is the most important number for a pool.
Is this really free?
Yes. No email, no signup, and nothing you type leaves your browser.
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Disclaimer: These free tools and templates are provided for general information and estimating purposes only. All results — including quantities, material and cost estimates, load, sizing, and span figures, scores, and any guidance or warnings — are rough approximations that may not fit your specific project, site conditions, local building codes, or current prices. They are not engineering, architectural, structural, legal, financial, or other professional advice, and are not a substitute for a licensed engineer, architect, contractor, or other qualified professional. Always confirm quantities, sizing, and structural, electrical, mechanical, and code requirements with a licensed professional and your local authority having jurisdiction before purchasing materials or performing any work. Werx makes no warranty as to accuracy and accepts no liability for any decision made using these tools. Use at your own risk. See our Terms of Service.