Pool Sand Calculator
A pool sand calculator looks up filter sand by tank diameter: a 24 in sand filter takes about 300 lb, which is six 50 lb bags, using typical maker capacities.
Pool sand calculator
A pool sand calculator tells you how many pounds of filter sand go into a sand filter. It takes the tank diameter, matches it to the closest size in a table of typical manufacturer capacities, and returns the weight. A 24 inch tank takes about 300 lb, which is six 50 lb bags.
The pool’s size does not enter the calculation. The sand sits in the filter tank next to the pump, and the tank holds a fixed amount.
The lookup in plain words
The calculator compares your tank diameter to six common sizes and picks the closest.
| Tank diameter | Sand | 50 lb bags | 25 lb bags |
|---|---|---|---|
| 16 in | 100 lb | 2 | 4 |
| 19 in | 150 lb | 3 | 6 |
| 21 in | 200 lb | 4 | 8 |
| 24 in | 300 lb | 6 | 12 |
| 27 in | 400 lb | 8 | 16 |
| 30 in | 500 lb | 10 | 20 |
If your diameter sits exactly halfway between two entries, the calculator picks the smaller one. When in doubt, use the amount printed in your filter’s manual.
Worked examples
A 24 in tank, the default:
- Match: 24 in is a listed size
- Sand: 300 lb
- Bags: 300 ÷ 50 = 6 bags of 50 lb
A 22 in tank:
- Distance to 21 in: 1 in
- Distance to 24 in: 2 in
- Closest is 21 in, so the sand is 200 lb, or 4 bags of 50 lb
A 30 in tank:
- Match: 30 in is a listed size
- Sand: 500 lb, or 10 bags of 50 lb
Why the manual wins
The table holds typical capacities. Filter makers set sand weights from the tank volume, the lateral design and the freeboard, which is the empty space above the sand. Two 24 inch tanks from different brands may hold different amounts. If the manual lists a number, use it.
How to measure the tank
- Turn the pump off and let the system depressurize.
- Measure across the widest part of the tank with a tape.
- Do not include the valve or any ring at the top.
- Compare to the model number in the manual.
Which sand to buy
Use the sand grade the manufacturer lists, usually a silica sand in a fine, uniform grain size. Avoid play sand, mason sand or beach sand. Uneven grains compact into a hard layer, and fine dust can pass through the laterals into the pool. Filter glass or zeolite media are alternatives that some manufacturers allow, but their quantities differ from sand, so follow the product instructions.
Changing the sand
- Shut off the pump and breaker.
- Open the drain and release pressure.
- Remove the multiport valve and cover the standpipe so sand stays out of it.
- Scoop out the old sand. A shop vacuum helps with the last bit.
- Inspect the laterals and standpipe for cracks, and replace damaged parts.
- Fill the tank partway with water to cushion the laterals.
- Pour in the new sand to the amount listed.
- Reassemble, backwash and rinse.
Follow your manual’s order of steps. If anything about the electrical side or the pressure vessel concerns you, hire a pool professional.
Common mistakes
- Sizing the sand from the pool volume. It depends on the tank.
- Pouring new sand onto old, dirty sand.
- Overfilling past the manufacturer’s fill line, which restricts flow.
- Using the wrong grade of sand.
- Skipping the backwash and rinse after the change, so dust clouds the pool.
Related tools
The pump has to match the filter. Use the pool pump size calculator to check flow, and the pool gallons calculator to find the water volume the system serves. For chemicals, see the pool chlorine calculator.
Frequently asked questions
Where do I find my sand filter's tank diameter?
Measure straight across the tank at its widest point with a tape, or read the model number and label on the tank. The size is often stamped or printed on the side. The manual lists the sand weight, and that figure overrides this calculator.
Why doesn't the calculator use my pool's size?
Filter sand fills the filter tank. It does not go into the pool. The amount depends on the tank's size, so a 24 in tank takes the same sand whether it serves a small pool or a large one. Pool volume matters for choosing the pump and filter size, not for the sand quantity.
What type of sand goes in a pool filter?
Filter makers usually specify a graded silica sand, often sold as number 20 grade, with a narrow range of grain sizes. Regular play sand or construction sand is the wrong size and can clog or pass through. Follow your filter manual.
How often does filter sand need replacing?
Many manufacturers suggest changing it every few years, often in the range of three to five, or sooner if pressure stays high after a backwash or water stays cloudy. Check your manual, since the interval depends on water chemistry and use.
What if my tank size falls between two in the table?
The calculator picks the nearest listed diameter. A 22 in tank is closer to 21 in than 24 in, so it returns 200 lb. When your tank is between sizes, look up the exact capacity in the manual or on the label.
Estimates only. Verify quantities with your supplier before purchasing.