Volume for an 18-Foot Round Pool
Free calculator with pre-filled dimensions • Updated March 2026
An 18-foot round pool at 4 feet deep holds approximately 7,614 gallons.
Open calculator with these dimensions →18-Foot Round Pool: Volume & Chemical Guide
The 18-foot round above-ground pool is the most popular residential pool size in America. At a standard 48–52 inch wall height (4 ft average water depth), it holds approximately 7,614 gallons — manageable for standard residential water supply and chemical maintenance.
Quick Facts
| Metric | Value |
|---|---|
| Volume | 7,614 gallons |
| Surface area | 254 sq ft |
| Fill time (garden hose) | 15–19 hours |
| Recommended pump | 1/2 HP (min 16 GPM) |
| Sand for filter | 150 lbs |
Startup Chemical Dosing
- Chlorine: 1 cup of liquid chlorine (12.5%) to raise 1 ppm
- pH adjustment: ~2 oz soda ash to raise pH by 0.1
- Alkalinity: ~1 lb baking soda to raise TA by 10 ppm
- Stabilizer (CYA): ~1 lb to raise 10 ppm (target 30–50 ppm)
Pro Tips
- Level the ground to within 1 inch. An 18-foot pool that is 2 inches off level has a visible water line difference and puts uneven stress on the walls. Rent a laser level ($40/day) for precision.
- Use a sand base, not grass. 2 inches of mason sand under the liner prevents rocks from poking through and provides a comfortable bottom. You need about 2 tons of sand.
- A solar cover reduces chemical costs by 50%. Sun breaks down chlorine rapidly. A $50 solar cover for an 18-foot pool pays for itself in 2–3 weeks of chemical savings.
Frequently Asked Questions
How many gallons in an 18-foot round pool?
At 4 feet of water depth, an 18-foot round pool holds approximately 7,614 gallons. The formula is: π × radius² × depth × 7.48. That is 3.14159 × 9² × 4 × 7.48 = 7,614 gallons.
How long to fill an 18-foot pool?
With a standard garden hose (400–500 GPH), filling 7,614 gallons takes 15–19 hours. Start filling in the morning and it should be full by the next morning.