20 × 40 ft pool volume
A 20 × 40 ft pool holds
32,900gal 125,000LAt an average water depth of 66 in.
Gallons at every fill
| Average depth | Holds |
|---|---|
| 48 in this page |
23,900 gal 90,500 L |
| 54 in this page |
26,900 gal 102,000 L |
| 60 in this page |
29,900 gal 113,000 L |
| 66 in this page |
32,900 gal 125,000 L |
What to add
| Fixes | Product | Add |
|---|---|---|
| Lower pH −0.5 pH |
HASA Dry Acid | 4.11 lb |
| Raise total alkalinity +40 ppm |
HASA Alkalinity Up | 18.44 lb |
| Raise pH +0.3 pH |
HASA Soda Ash | 9.87 lb |
| Raise free chlorine +2.5 ppm |
HASA CHLOR | 2.63 qt |
| Shock the pool +9.5 ppm |
HASA CHLOR | 10.01 qt |
Not quite your pool?
Change any measurement and every figure on this page is worked again: the gallons, the drawing, the fill table and each dose.
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Updated October 2026
Sources and dates
Ranges are quoted from the code named beside them, product strengths from the manufacturer's own product page, each retrieved on the date shown.
- COMAR 10.17.01.45 A(1) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- HASA · https://hasa.com/pool-chemical-calculator · 2026-09-17
- COMAR 10.17.01.45 A(2) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- Florida 64E-9.004 (1)(d)2 · http://flrules.elaws.us/fac/64e-9.004 · 2026-09-17
- HASA Dry Acid · https://hasa.com/product/dry-acid · 2026-09-17
- HASA Alkalinity Up · https://hasa.com/product/alkalinity-up · 2026-09-17
- HASA Soda Ash · https://hasa.com/product/soda-ash · 2026-09-17
- HASA CHLOR · https://hasa.com/product/hasachlor · 2026-09-17
This site publishes calculated water volumes and chemical quantities for home pool and spa owners. It is not a health, safety or professional service, and it does not replace the instructions printed on the product you are holding. Not affiliated with, endorsed by or sponsored by HASA, Pyrock Chemical, Pentair, Hayward, Sonoma Hot Tubs, the Centers for Disease Control and Prevention, or any state health department. Product names are the trademarks of their owners and appear here only to identify the strength of what is in the container.