Pool calculators
Pool Refill Time Calculator
Time how long your hose takes to fill a bucket, enter how much water you need, and see how long the fill or top-up takes and how fast the level rises. No guessing about your tap: you measure your own flow.
Your hose and your pool
Based on your own bucket timing, not on an assumed tap flow. Water pressure can change during the day, so treat the result as an estimate (our note).
Time to fill = gallons to add ÷ your hose flow in gallons per minute. Measure the flow yourself: if a 5-gallon bucket fills in 60 seconds, your hose gives 5 GPM. At 5 GPM, topping up 2 inches in a 16 × 32 ft pool (about 640 gallons) takes a little over 2 hours, and filling a 24 ft round pool with 4 ft of water (about 13,540 gallons) takes about 45 hours.
How to measure your hose flow with a bucket
Garden hose flow depends on your water pressure, the tap, the hose length and its diameter (our explanation), so a number from someone else's garden says little about yours. A bucket and a stopwatch are all you need:
- Use a bucket you know the size of, for example a 5-gallon bucket.
- Open the tap fully, or the way you will use it for the pool, with the hose you will use.
- Time how many seconds it takes to fill the bucket to the 5-gallon mark.
- Enter the bucket size and the seconds in the calculator. Flow (GPM) = gallons ÷ (seconds ÷ 60).
Screws onto the hose and counts the gallons that go into the pool, so you can see exactly how much you added instead of watching the level.
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See hose flow meters on AmazonHow long does it take to fill a pool with a garden hose?
| Pool volume | 5 GPM | 8 GPM | 10 GPM | 12 GPM |
|---|---|---|---|---|
| 5,000 gal | 16.7 h | 10.4 h | 8.3 h | 6.9 h |
| 10,000 gal | 33.3 h | 20.8 h | 16.7 h | 13.9 h |
| 15,000 gal | 50.0 h | 31.3 h | 25.0 h | 20.8 h |
| 20,000 gal | 66.7 h | 41.7 h | 33.3 h | 27.8 h |
| 25,000 gal | 83.3 h | 52.1 h | 41.7 h | 34.7 h |
Hours = gallons ÷ GPM ÷ 60. Our calculation. Not sure of your gallons? Use the pool volume calculator.
Topping up after evaporation, splash-out or backwashing
For a top-up you do not need the whole volume, just the inches. The volume calculator gives "water per inch of level" for your pool; this calculator multiplies it by the inches you want to add. It also shows how fast the level rises with your hose, so you know when to come back and turn it off.
Level dropped fast?
If you top up a lot every week, check whether it is evaporation or a leak with our water loss calculator.
Watch the skimmer
UF/IFAS Extension gives about halfway up the skimmer (or mid-way up the tile line) as the normal level to come back to, so the skimmer can pull the surface water (our explanation).
Set a timer
A forgotten hose overflows the pool and washes chemistry down the drain. The level rise in the calculator tells you when to check (our advice).
After a big fill: test the water
New water changes your chemistry. A big top-up dilutes chlorine and stabilizer, and a fresh fill starts from whatever your tap water contains. Test chlorine and pH before anyone swims (the CDC's home pool range is pH 7.0 to 7.8 and at least 1 ppm free chlorine, 2 ppm with stabilizer), then check alkalinity and calcium hardness and the overall balance in our LSI calculator. The order to fix things in is on pool chemistry essentials.
Filling a whole pool takes a lot of water at once. Some areas have watering rules or offer bulk water delivery; check with your water supplier before a full fill (our advice).
Tips to fill faster
- Use a shorter, wider hose. A long, narrow hose delivers less water than a short, wide one at the same pressure (our explanation). Time your bucket again after you change the hose.
- Use two separate taps. Two hoses on one tap share the same flow; two taps on different lines usually add up (our explanation). Time each one.
- Do not leave a draining or filling pool alone. UF/IFAS warns never to turn your back on a draining pool; a filling one can overflow too (our advice). Check it at the times the calculator gives you.
Pool refill FAQ
How long does it take to fill a pool with a garden hose?
Divide the gallons by your hose flow. At 5 GPM, a 10,000-gallon pool takes about 33 hours; at 10 GPM, about 17 hours. Measure your own flow with a bucket for a real answer.
How many gallons per minute does a garden hose give?
It depends on your pressure, tap and hose. Time a 5-gallon bucket: 60 seconds is 5 GPM, 30 seconds is 10 GPM.
How long does it take to raise the pool level by one inch?
Gallons per inch ÷ GPM. A 16 × 32 ft pool has about 319 gallons per inch, so at 5 GPM that is about 64 minutes.
Do two hoses fill a pool twice as fast?
Only if they run from separate taps with their own flow. Two hoses on one tap split the same water (our explanation). In the calculator, only count hoses on separate taps.
Should I add chemicals right after filling?
Test first, then adjust in Taylor Technologies' order: alkalinity, then pH, then calcium hardness; balance before you shock (HTH label). Our pool chemistry pages walk through each step.
Sources
- CDC: Home pool and hot tub water treatment and testing (pH and chlorine targets)
- UF/IFAS Extension: Pools and hurricanes (water level halfway up the skimmer, never leave a draining pool)
- Taylor Technologies: LSI calculator (order of adjustments)
Flow and fill-time figures are our own calculations from the formulas on this page.