Using the Pool Volume Calculator
Build the water footprint from measured sections, assign representative depths, and review the geometry before using the volume for treatment calculations.
Measure The Water, Not The Shell
Measure the inside water dimensions and the actual water depth. Divide an irregular pool into rectangles and circles that can each be represented by one depth. Use more sections where the floor changes quickly, such as steps, benches, transitions, or a sloped deep end.
A number without a unit is treated as feet. The measurement fields also accept feet, inches, yards, and meters, including entries such as 12 ft 6 in, 12' 6", or 3.8 m. Enter positive width, length, diameter, and depth values; the section form applies a one-inch minimum when a section is added or updated.
Understand The Calculation
Each section has a horizontal footprint and one representative depth.
PoolKit converts section volumes using 7.48052 U.S. gallons per cubic foot, consistent with the NIST U.S.-gallon definition.[1] Gallons and liters are displayed as whole units; a tilde marks a rounded display value.
The depth of a section is not a floor profile. For a sloped section, enter a representative average depth or divide the slope into smaller sections. A volume error carries into every later dose calculation that uses that volume, which is why CDC pool-chemical training guidance specifically includes calculating venue volume and matching chemical quantity to that volume.[2]
Resolve Overlaps Before Relying On The Total
Separate sections that overlap can count the shared water twice. PoolKit reports “Review overlapping sections” when it detects that condition. Select overlapping or touching sections with the same add/subtract operation and use Merge to create one static footprint.
When sections are merged, PoolKit assigns an area-weighted average of their entered depths. Review that depth after the merge; it is a starting estimate and may not describe a complex floor. The merged outline is static and replaces its source sections, so correct measurements before merging or recreate the source sections when the footprint is wrong.
A merged circle is stored as a 72-sided outline. Its area is about 0.13% smaller than the original circle calculation. This is a drawing approximation, not a claim about measurement accuracy; leave a circle unmerged when that small difference matters.
Use Subtract volume for a dry feature contained inside a water section, such as an island footprint. Keep the subtracting shape inside the surrounding section. PoolKit removes that footprint at the surrounding section’s depth; the contained subtracting shape’s own depth does not change the total. It is not intended to describe a separate negative pool.
The Sections list shows each shape’s footprint multiplied by its own depth. Contained sections are combined using the surrounding section’s depth, so the listed section values do not always add directly to the calculated total. Review the drawing and use the combined total.
Review, Save, And Verify
Compare the result with construction drawings, fill-meter records, or a previous trusted estimate when available. Recheck unusually large differences before using the volume for dosing, turnover, or water-replacement work.
The drawing remains local unless it is saved. When signed in, Save Geometry stores the drawing for the selected pool or spa. Sync Volume is a separate action that copies the calculated gallons to that profile. The Geometry Data text can be copied for backup or imported into PoolKit later.
References
- National Institute of Standards and Technology. NIST Guide to the SI, Appendix B.8. Used for the U.S.-gallon-to-liter conversion.
- CDC. Pool Chemical Safety. Used for the operational importance of venue volume and volume-based chemical calculation.