Calculator · 4 min

Pick-location refill calculator

For one product, estimate when to refill its pick location and how often refills may be needed.

No sign-in · Results are not sent to Voodoo · Assumptions shownNot sure about a term? Open the plain-English glossary

Your numbers

Describe your operation

Example values are already filled in so you can see how the tool works. Replace them with measurements from your operation. Results update immediately.

Open the plain-English glossary

What the main answer means

If the result says 42 units, release a refill when available stock falls to about 42. That is the trigger—not the refill quantity.

Average daily demandAverage units picked per operating day for this one product.

units

Example: 96 units/dayDaily demand standard deviationHow much daily demand normally varies. In a spreadsheet, use STDEV.S on at least 20 representative daily totals.

units

Example: 22 unitsReplenishment lead timeWorking days from noticing a refill need until stock reaches the pick location.

days

Example: 0.25 day = one quarter of the staffed dayService factor (z)Protection level used in the stock formula. 1.28≈90%, 1.65≈95%, 2.05≈98%, 2.33≈99%.

Example: 1.65 for a 95% targetCase packUnits contained in one full case.

units

Example: 24 units/casePhysical face capacityMaximum units that physically fit in this pick bin or shelf position.

units

Example: 144 unitsUsable capacityPercent of physical space normally usable after allowing for imperfect fit and operating room.

Example: 85% of physical capacity

Show the math and assumptions

Refill trigger = average demand during lead time + extra stock for ordinary demand variation.

Approximate refills/day = daily demand ÷ (usable capacity − refill trigger).

How to read this

The yellow result is the main planning answer. Change any uncertain input to see whether the answer is stable. Treat this as a starting point for a small real-world test, not a promise.

Reorder point42 unitsTrigger a refill when available units fall to about this level; it is not the refill quantity.

Cases at reorder point2The reorder-point stock expressed as full cases.

Usable face capacity122 unitsMaximum planned units after the usable-space adjustment.

Approx. replenishments / day1.2Daily demand divided by the expected refill quantity (usable capacity minus the refill trigger).

Demand during lead time24Average units expected before a requested refill arrives.

Safety stock component18Extra stock allowed for ordinary demand variation.

Use the staffed operating clock. A quarter-day refill lead time during working hours is not the same as overnight or weekend exposure.

What to check nextThis models one product at one pick location. Highly seasonal or intermittent demand needs a more careful model than this simple normal-demand formula.

After the calculation

Test the answer on a small piece of real work.

Measure today’s result first. Write down what success means, what can go wrong, and how workers will continue if the new method fails.

Plan a small trial Build a go-live test