Pool Volume Calculator — Gallons, Liters & Fill Time

    Calculate your swimming pool volume in gallons and liters. Supports rectangular, round, and oval pools. Get fill time estimates and water cost based on average garden hose flow rates and municipal water prices.

    Average depth = (shallow + deep) / 2 = 5.5 ft

    Tips

    • Measure the actual water line dimensions, not the outer shell or decking dimensions
    • For pools with a flat bottom, use the same depth for both shallow and deep end
    • Chemical dosing is based on gallons — an accurate volume prevents over- or under-treating
    • Using two garden hoses at once roughly doubles your fill rate
    • Call your water utility before filling — some offer discounted pool fill rates or sewer credits
    Estimates only — actual volume varies by pool shape irregularities, ledges, and benches. Always confirm with your pool builder.

    Example Calculation

    Have a 16x32 foot rectangular pool with a 4-foot shallow end and 8-foot deep end? The average depth is 6 feet, giving you about 22,979 gallons (86,969 liters). At a typical garden hose flow rate of 9 gallons per minute, filling takes roughly 43 hours.

    Rectangular Pool Volume Reference

    Gallons for common rectangular pool sizes at uniform depth (length x width x depth x 7.48).

    Pool Size4 ft Depth5 ft Depth6 ft Depth
    12 x 248,61710,77112,926
    15 x 3013,46416,83020,196
    16 x 3215,31919,14922,979
    18 x 3619,38824,23629,083
    20 x 4023,93629,92035,904

    Frequently Asked Questions

    How many gallons of water does a typical pool hold?

    A typical residential pool holds 10,000 to 30,000 gallons. A 12x24-foot pool at 5 feet average depth holds about 10,771 gallons. A larger 20x40-foot pool at 6 feet average depth holds about 35,904 gallons.

    How do I calculate pool volume for chemical dosing?

    Pool chemical dosing is based on gallons. Calculate your pool volume using length x width x average depth x 7.48 (for rectangular pools). Most chemical labels provide dosing per 10,000 gallons. Accurate volume prevents over- or under-treating your water.

    How long does it take to fill a pool with a garden hose?

    A standard garden hose flows about 9 gallons per minute (540 gallons per hour). A 15,000-gallon pool takes roughly 28 hours to fill. A 25,000-gallon pool takes about 46 hours. Using two hoses cuts the time in half.

    How much does it cost to fill a pool with water?

    At the national average of about $4 per 1,000 gallons, filling a 20,000-gallon pool costs roughly $80. Rates vary by location — some utilities charge $2-$8 per 1,000 gallons. Many water utilities offer a one-time pool fill rate if you call ahead.

    What is average depth and why does it matter?

    Average depth is the midpoint between your shallow end and deep end: (shallow + deep) / 2. A pool with a 3-foot shallow end and an 8-foot deep end has a 5.5-foot average depth. Using average depth gives an accurate volume estimate for pools with sloped bottoms.

    How do I calculate the volume of a round or oval pool?

    For round pools, use pi x radius squared x average depth x 7.48. For oval pools, use pi x (long radius) x (short radius) x average depth x 7.48. The calculator handles these formulas automatically — just enter your pool dimensions.