Pool, Spa & Water Treatment Chemistry worked example

Chemical Inventory Days with usable stock above reserve of 16 gal or lb: a worked example in pool, spa & water treatment chemistry

This worked example runs the chemical inventory days numbers for a tougher week than the baseline: usable stock above reserve of 16 gal or lb instead of the typical 32 gal or lb. Estimate days of chemical inventory from on-hand volume, daily use, and reserve stock.

The inputs for this scenario

  • Usable stock above reserve: 16 gal or lb (the input this scenario stresses; the baseline uses 32)
  • Average daily chemical use: 2.5 gal or lb / day (held at the documented default)
  • Inventory efficiency factor: 0.98 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Inventory days = usable stock above reserve / average daily use x efficiency factor.
  • Ratio works out to 6.27 days at these inputs, and this is the headline figure for the scenario.
  • Raw ratio works out to 6.4 value at these inputs.
  • Shrink factor works out to 0.98 x at these inputs.
  • Daily use works out to 2.5 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where usable stock above reserve sits at 32 gal or lb and the headline result is 12.54 days, this scenario comes in 50% below the baseline at 6.27 days.
  • Use it to set reorder timing on a service route or at a facility, especially heading into peak-demand summer weeks. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Ratio: 6.27 days (headline result)
  • Raw ratio: 6.4 value
  • Shrink factor: 0.98 x
  • Daily use: 2.5 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Chemical Inventory Days calculator, set usable stock above reserve to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.