When determining the number of gallons needed to fill a swimming pool, there are a few key factors to consider: the shape of the pool, the dimensions of the pool, and the average depth. For a basic rectangular pool like yours with dimensions of 16 feet by 32 feet, we can use a simple formula to calculate the volume and then convert that to gallons.
Step 1: Calculate the Volume of the Pool
To find the volume, we multiply the length x width x average depth. For a 16×32 rectangular pool, the calculations would be:
- Length = 16 feet
- Width = 32 feet
- Average Depth = Let’s assume 4 feet
Volume = Length x Width x Average Depth
Volume = 16 x 32 x 4
Volume = 2048 cubic feet
Step 2: Convert Volume into Gallons
Now that we know the volume of the pool in cubic feet, we need to convert that into gallons. One cubic foot holds approximately 7.48 gallons of water. To convert cubic feet to gallons, we simply multiply the volume by 7.48.
2048 cubic feet x 7.48 gallons per cubic foot = 15,318 gallons
Conclusion
For a rectangular pool with dimensions of 16 feet long by 32 feet wide, with an estimated average depth of 4 feet, the total number of gallons needed to fill the pool is approximately 15,318 gallons.
This calculation can vary slightly depending on the actual average depth of your pool, any rounded corners or variations in shape from a perfect rectangle, and margin of error in measurements. But it provides a reasonable estimate to use when planning for a new pool fill.
Factors That Impact Volume Calculations
When calculating the amount of water needed to fill a pool, there are a few important factors to keep in mind that can impact the final volume and gallons:
- Shape of the pool – Rectangular or square pools are the simplest calculations. Pools with rounded corners, oval shapes or other designs need more complex formulas.
- Dimensions – The length, width and average depth all factor into the volume. Small measurement errors can change the final gallon amount.
- Depth variations – Many pools have shallow and deep ends or other depth differences. This needs to be accounted for in the average depth used.
- Displacement – The volume of the pool itself and any stairs or benches displace water and should be subtracted from the total volume.
- Slope – For in-ground pools, the slope of the surrounding ground can affect how much volume is needed for the outer edges.
Knowing the exact dimensions and depths along each point of the pool will provide the most accurate final gallon amount. Rounding too much or using estimates can throw the calculation off.
Tips for Measuring Your Pool Accurately
Here are some tips to get precise measurements of your swimming pool to use for volume and gallon calculations:
- Use a long tape measure stretched across the length and width. Take multiple measurements and average them.
- For curved pools, break the shape down into smaller rectangles and triangles to get total area.
- Measure depth at several points – the shallow end, deep end, and a few places in between. Average them.
- Account for stairs, benches, swimouts or other areas that displace water.
- For sloped pools, take depth measurements at the outer edges to factor in the slope.
- Use a pool calculator or formula online to do the cubic feet to gallon conversions.
- Remeasure if something seems off compared to the pool’s designed shape and size.
Taking the time to carefully measure and calculate the pool volume will give you an accurate gallon amount and help you plan and budget for chemicals, water delivery, and other pool maintenance needs.
Standard Pool Shapes and Sizes
There are a few very common pool shapes and dimensions that many homeowners use for their designs:
Kidney-Shaped Pools
- Length: 28-34 feet
- Width: 14-18 feet
- Average depth: 3.5-5 feet
- Volume: 15,000 – 30,000 gallons
Rectangular Pools
- Length: 20-40 feet
- Width: 10-20 feet
- Average depth: 4-6 feet
- Volume: 15,000 – 40,000 gallons
Oval Pools
- Length: 24-40 feet
- Width: 12-20 feet
- Average depth: 4-6 feet
- Volume: 15,000 – 35,000 gallons
Of course pools can be customized to any shape and size, but these examples give you an idea of typical backyard pool dimensions.
How Pool Volume Impacts Maintenance
The volume of water in your pool affects several aspects of regular maintenance and care. Here are some things to consider with pool volume:
- Chemical dosing – Most chemicals are added based on gallons of water. A larger pool requires more chemicals added.
- Filtration – Bigger pools need more filter capacity to properly turnover the water volume.
- Heating – It takes more energy to heat larger volumes of water for a pool.
- Filling – More water gallons means longer fill times from a garden hose or requiring a water truck.
- Draining – Larger volumes take more time and pumps to drain out old water for maintenance.
- Cleaning – More surface area in the pool itself requires extra time cleaning and scrubbing.
A good rule of thumb is allow 1-2 hours of maintenance per 10,000 gallons of water in your pool each week. Keep the pool’s volume in mind when budgeting your time and supplies.
Formulas for Different Pool Shapes
The volume formula to use depends on the shape of your pool. Here are some of the most common pool shape formulas:
Rectangle/Square Pool Volume
Volume = Length x Width x Average Depth
Oval Pool Volume
Volume = Length x Width x Average Depth x 0.8
Kidney-Shaped Pool Volume
Volume = 0.57 x Length x Width x Average Depth
Custom Pool Volume
Break the shape down into smaller rectangles and triangles. Calculate each individually then add together for total volume.
Having the right formula for your pool shape ensures your volume and gallon calculations are accurate when planning for water needs, chemicals, and maintenance.
How Pool Volume Affects Costs
The overall volume of water in your pool impacts several costs for maintenance and operation:
- Filling costs – Requires more water to fill up a bigger pool, which adds to your water bill.
- Chemical costs – More gallons require larger amounts of chemicals to properly treat and balance.
- Heating costs – It takes more energy to heat larger volumes of water from a pool heater.
- Pump costs – Bigger pools need more powerful pump and filter systems to circulate the water.
- Labor costs – More time and work is needed to properly clean larger pools.
For a very small pool, maintenance costs may be $50-100 per month. For very large backyard pools, monthly costs can run over $200. Keep operating expenses in mind when selecting your desired pool size.
Estimating Volume Costs
Here is a quick guide on how to estimate costs based on pool volume:
- Filling: $3-5 per 1,000 gallons
- Chemicals: $0.50-$1 per 1,000 gallons monthly
- Heating: $100-$300 per 10,000 gallons monthly
- Pumps: $200-$500 per 10,000 gallon system
- Labor: $50-$100 per 10,000 gallons monthly
Multiply your pool’s volume by these factors to calculate how much you’ll spend on ongoing operation based on size.
Choosing the Right Pool Size
When planning a new pool installation, here are some things to think about in choosing the right size:
- How much space do you have available in your yard?
- What pool shapes do you like the aesthetic of?
- Will it be used for swimming laps, fitness or just leisurely use?
- Do you plan to use it for entertaining large groups?
- What features do you want – spa, slide, water features?
- How much time do you have for upkeep and maintenance?
- What is your budget for construction and operation costs?
Take all these factors into account as you select dimensions and volume. An experienced pool contractor can also provide guidance on recommended sizes and shapes for your property and needs.
Key Takeaways
- Calculate pool volume by multiplying length x width x average depth.
- Convert cubic feet measurements to gallons based on 7.48 gallons per cubic foot.
- Carefully measure all dimensions to get accurate volume calculations.
- Bigger pool volumes impact maintenance time, chemical costs, water use and heating.
- Factor in size, shape, features and budget when planning your ideal pool.
