Pool Fill Time Calculator — How Long to Fill a Pool?
Enter your pool size and hose flow rate to see how many hours (or days) it takes to fill, plus an optional water-cost estimate. No sign-up, no data stored.
Fill time
How pool fill time is estimated
- Gallons = pool volume entered directly, or length x width x average depth x 7.5 (rectangular pool).
- Minutes = gallons ÷ flow rate (GPM).
- Hours = minutes ÷ 60; shown as days when over 24 hours.
- Cost = gallons ÷ 1,000 x water rate per 1,000 gallons (optional).
The 7.5 is the number of gallons in one cubic foot of water. Average depth is usually the midpoint between the shallow end and the deep end - for a 3-ft to 6-ft pool, that is 4.5 ft.
Pool size → fill time reference
Standard 5/8-in garden hose at 10 GPM.
| Pool size | Gallons | Time (10 GPM) | Two hoses (20 GPM) |
|---|---|---|---|
| 10 ft round, 48 in | 3,500 | 5.8 h | 2.9 h |
| 12x24 above ground | 8,000 | 13.3 h | 6.7 h |
| 16x32 in-ground | 15,000 | 25 h | 12.5 h |
| 18x36 in-ground | 21,000 | 35 h | 17.5 h |
| 20x40 in-ground | 30,000 | 50 h | 25 h |
Last updated: October 2026 · Flow rates vary with hose length, diameter and spigot pressure. Measure your actual rate once by timing a 5-gallon bucket fill.
Pool fill time FAQ
A typical garden hose delivers 5-10 gallons per minute; a 50-ft hose with kinks can drop to 3-4. A 5/8-in hose with short runs and no sprinkler nozzle fills noticeably faster than a 1/2-in hose.
Use two hoses at once - you roughly halve the time. Keep the hose straight (no coils or kinks), run it from an outdoor spigot with good pressure, and avoid sprinklers or spray attachments that restrict flow.
No - pool surfaces are built to handle water weight. What matters is flow rate on the finish: avoid a high-pressure hose on new plaster for the first week, and always fill to the middle of the skimmer.
For a rectangular pool: length x width x average depth x 7.5 = gallons. Round and irregular pools need more complex math - use the pool volume calculator, or check your pool's sticker or paperwork.
Many municipalities restrict pool filling during drought or charge higher rates. Check local watering rules first - a large pool can take 20,000+ gallons and show up loudly on your bill.
Related calculators & guides
How Long Does It Take to Fill a Pool?
Real-world fill times, hose flow rates and how to speed things up safely.
Read the guide →Pool Volume Calculator
Get exact gallons for round, rectangular and irregular pools.
Use the calculator →