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Consumables reorder calculator

Plan a reorder trigger and whole-pack purchase quantity from actual usage, lead time, reserve stock and incoming orders.

Calculator

Sources, assumptions & review

User input Values you provide

Check units, basis and local values before relying on the output.

Calculated Transparent model output

Metricon applies the displayed formula to the inputs on this page.

Assumption Model boundary

Scenario inputs and defaults are not measured facts unless you supplied them from a controlled source.

Review Human decision

Compare the result with approved product directions, actual operating conditions and accountable judgement.

FormulaReorder point = daily usage × lead time + reserve · Target = usage × (lead time + review interval) + reserve

Quantity unit

Name the unit used for every stock quantity, such as litres, rolls or pieces. It is included in your memo.

Average daily usage

Use the same quantity unit throughout: litres, rolls, pieces or another chosen unit.

Supplier lead time

Days from ordering to usable receipt; use your actual supplier experience.

days

Replenishment review interval

Days between planned stock reviews. This determines the target stock horizon.

days

Reserve stock

Reserve in your chosen unit. It is an explicit assumption, not a calculated service-level buffer.

Usable stock on hand

Exclude expired, damaged or unavailable stock.

Confirmed incoming quantity

Same unit; include only orders expected within the planning horizon.

Quantity per purchasable pack

Same unit, such as 5 litres, 6 rolls or 100 pieces per pack.

Stock review —

How it works

Choose one stock unit

Keep daily usage, reserve, usable stock, on-order quantity and pack size in the same unit. Use measured consumption for the relevant item.

Enter the replenishment timing

Enter delivery lead days and review days. Add your chosen reserve quantity rather than treating it as a percentage.

Review trigger and target

Compare stock plus on-order quantity with the reorder point. The target also covers the review period; the model rounds any target shortfall up to whole packs.

Check before ordering

Review demand changes, supplier dates and whether incoming stock will arrive in time. Use the result to plan a purchase rather than treating it as an automatic order.

Frequently asked questions

How do the reorder point and target differ?

The reorder point covers daily usage during lead time plus reserve. The target covers lead time and the review period plus reserve. Review is due when stock position is at or below the reorder point.

What does stock position include?

Usable stock plus the on-order quantity you enter. The model does not schedule individual deliveries or confirm availability, so check arrival dates and exclude unusable stock.

Why is the purchase quantity rounded up?

A positive target shortfall is divided by pack size and rounded up to whole packs. Zero daily usage is flagged for demand review; reserve and incoming-stock assumptions still need checking.