Order Quantity Calculator

Work out how much of a stock item to order for the next period, from the consumption of the last period, the days the item was out of stock and the stock you hold now.

Quantities are in your own stock unit (pieces, boxes, kilograms, litres).

Your figures

Everything is calculated in your browser. Nothing is sent to us or stored.

Period length (days)

The period that the consumption below refers to.

Consumption in the period

Quantity issued or used during the period.

Days out of stock

Days in the period with no stock to issue. Must be less than the period length.

Stock on hand

I know it: enter it

Calculate it from stock movements

Stock on hand (E)

Quantity in stock now.

Maximum stock method

Months of average consumption

Maximum stock = average monthly consumption × months of stock you want to hold.

Twice the adjusted consumption

Maximum stock = adjusted consumption × 2.

Months of maximum stock (M)

How many months of average consumption you want to hold at most. Decimals are allowed, for example 1.5.

Requested quantity (J) (optional)

Requested quantity (J)

Only if you want to order a different quantity from the calculated one.

Result

Fill in the period length, consumption, days out of stock, stock on hand and, for the first method, the months of maximum stock. The result appears here.

This calculation does not model safety stock or lead time separately; the choice of maximum stock months should be made to cover them.

The calculation logic is inspired by the definitions in the OpenLMIS requisition template; the code was written independently.

Many items at once

The Excel template does the same calculation for a list of items, row by row, with live formulas. It gives the same results as this page.

Download the Excel template