How to use the pool shock calculator
Prepare the values for this calculation
Calculate chlorine product mass from pool volume, desired free-chlorine increase and product active-chlorine percentage. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Pool volume (L): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Current free chlorine (ppm): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Target free chlorine (ppm): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Product available chlorine (%): enter a value at least 1e-06 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Chlorine product required first. With the unchanged example inputs, it is 0.30769231 kg. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Pool volume (L) from 50000 to 55000. The resulting Chlorine product required is 0.33846154 kg. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Pool Shock Calculator formula
Pure chlorine mass=volume(L)×Δppm mg/L; product mass=pure mass/active fraction.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Pool volume (L) | minimum 0 | 50000 |
| Current free chlorine (ppm) | minimum 0 | 1 |
| Target free chlorine (ppm) | minimum 0 | 5 |
| Product available chlorine (%) | minimum 1e-06; maximum 100 | 65 |
Worked example
Using the example inputs above, the chlorine product required is 0.30769231 kg.
- Chlorine product required
- 0.30769231 kg
- Required chlorine increase
- 4 ppm
- Pure available chlorine mass
- 0.2 kg
Results and assumptions
Stoichiometric concentration arithmetic only; product labels, pool chemistry, cyanuric acid, pH and local safety instructions can change the appropriate treatment.
Fix an input or unexpected result
Pool volume (L) is required. Enter pool volume (l) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.