Pool Volume Calculator & Sizing Guide
Pool volume influences water chemistry, circulation, filtration, heating and sanitizer sizing. For a manufactured fiberglass pool, the manufacturer's published water capacity is normally a better starting point than estimating from exterior dimensions.
Rectangular approximation
Length × width × average water depth × 7.48 = approximate gallons.
Average depth is generally the shallow water depth plus deep water depth divided by two when the floor changes gradually.
Why fiberglass pools are different
Benches, steps, tanning ledges, spas and curved walls displace water. That means a simple rectangular calculation can overstate actual capacity. Use the current manufacturer capacity for the exact shell when available.
Why volume matters
- Chemical dosing
- Salt-chlorinator sizing
- Heating calculations
- Circulation planning
- Filter and equipment selection
Example
A simple 30 ft × 14 ft pool with an estimated 4.5 ft average water depth would calculate to roughly 14,137 gallons before accounting for benches, steps or other displacement.
For a new fiberglass pool, browse Fiberglass Pool Packages and use the manufacturer's model data whenever available.