How Much Does Your Pool Need?
Start with your pool’s measurements and fresh water tests. Work out a dose, then compare bags and bottles.
Formulas, sources and limits: see our methodology
Step 1: pool volume
Estimate gallons from your pool dimensions.
Save your measured volume in a Pool Card so you can use it in the chemistry calculators. If the water level or dimensions change, work out the gallons again.
Calculate my pool's volume →Already know your gallons? Skip to all calculators →
Why volume first?
- A larger pool needs more salt for the same change in ppm.
- Your chlorine dose also scales with the gallons you’re treating.
- You can save a Pool Card in this browser without signing up.
Choose the task you need help with
See all calculators →Just opened my pool
Equipment and water checks after winter
Pool is green or cloudy
Water tests and treatment steps
Salt cell says low salt
Test salt before adding more
My test results need attention
Work out what to add from a fresh test
I'm a new pool owner
Start with the basics
I have an above-ground pool
Use the water depth and pool dimensions
Salt and Chlorine Calculators
Test first, then work out how much to add.
Salt Calculator
Use a fresh salt test and your generator’s limits to plan a first addition. Pool gallons set the amount; the bag count helps you shop.
Chlorine Calculator
Start with fresh free chlorine, pH and CYA tests. Your CYA reading helps set the minimum FC target. Use the label’s application directions, circulate and retest before adding more.
Fall closing season
Getting ready to close your pool?
Choose closing targets for your pool finish and expected coldest water temperature. Test before adjusting the water, and follow the closing guide and your equipment manuals for freeze protection.
Supplies for the Job Ahead
Choose supplies after testing the water and deciding what needs attention.
Affiliate disclosure: We may earn a commission when you buy through links on this page. Our recommendations are independent and this costs you nothing extra. Learn more›
A bigger pack can leave you with chemicals you can’t use or store safely. Compare the package size with your dose estimate, then check the current price and storage instructions before buying.
Opening your pool
Before buying opening supplies, check your equipment and test the water. Work through the guide to decide what needs adjusting.
- Check price on Amazon →
1. Pool shock
In The Swim
12 x 1 lb bags
- Check price on Amazon →
2. Pool salt
Morton
40 lb bag
Treating a green pool
Green water? Test first. Use the guide to find a treatment target from your stabilizer reading and work through the completion checks.
- Check price on Amazon →
1. Pool shock
In The Swim
12 x 1 lb bags
- Check price on Amazon →
2. Liquid chlorine
Champion
1 gallon jug (12.5%)
- Check price on Amazon →
3. CYA / stabilizer
In The Swim
5 lb bag
Supplies for Routine Care
Use a fresh water test to decide what needs adjusting. Once you have a dose estimate, compare it with the bags or bottles you can buy.
- Check price on Amazon →
1. Liquid chlorine
Champion
1 gallon jug (12.5%)
- Check price on Amazon →
2. Baking soda (alkalinity up)
In The Swim
25 lb bag
Guides for Your Next Pool Task
Work through the next job, from opening after winter to treating green water.
How to Open a Pool
SpringTest the water before choosing your opening chemicals.
How to Fix a Green Pool
SummerFind an algae-treatment target from your tests, then keep checking until treatment is complete.
How to Close a Pool
FallGet your water balance and winterization plan ready before freezing weather arrives.
Pool Chemistry Basics
Year-roundUnderstand free chlorine, pH, alkalinity, stabilizer and calcium hardness.
Start with Your Pool’s Shape
How the calculators work
Documented methods
You can read the formula behind your result and where it comes from. Use your own measurements and product strength, and read the tool’s assumptions before adding anything.
Compare Bags and Bottles
See how your dose estimate compares with a bag or bottle. Measure the first addition, follow the staged instructions and retest before adding more.
Free to use
No login or payment is needed to use the calculators. We may earn a commission when you buy through product links.
What to Look For in Your Test Results
Use these ranges as a starting point. Choose your target using your pool-surface instructions, measured stabilizer and exact equipment manual.
Free Chlorine (FC)
Use measured CYA to set the minimum
FC must meet the minimum for measured CYA and the chlorine label’s re-entry range. CDC minimums are 1 ppm without stabilizer and 2 ppm with it; CYA can require more. Test FC and pH at least twice daily. Before swimming, check that the water is clear, the bottom is visible and there is no visible algae.
Chlorine calculator →pH
7.2–7.8
High chlorine can distort a color-based pH test. Use a valid reading alongside sanitizer tests and the other water-balance checks.
pH calculator →Total Alkalinity (TA)
80–120 ppm
Alkalinity helps buffer pH. Take fresh pH and TA readings together before choosing an adjustment.
Alkalinity calculator →Cyanuric Acid (CYA)
30–50 ppm
Stabilizer helps chlorine last in sunlight, but higher CYA calls for a higher FC target. For a salt pool, use your exact generator manual to choose CYA.
CYA calculator →Calcium Hardness
Choose for your surface and water balance
Calcium hardness and LSI don’t diagnose metal corrosion. Choose calcium hardness from your surface and equipment instructions and a full water-balance assessment, including temperature. Have suspected metal corrosion assessed separately.
Calcium calculator →Salt (SWG pools)
Check your exact cell manual
Choose your exact generator model before estimating salt or water exchange. For a custom model, copy the target and operating limits from its manual.
Salt calculator →