Reorder Point and Safety Stock Planner

You run out of the fast sellers while the slow ones pile up. Reordering by feel works until a supplier is late or a busy week hits, and then the shelf is empty on the day it matters.

For each item the app turns your average daily sales, how much they vary and how long the supplier really takes into two numbers: safety stock and the reorder point. Enter a daily demand figure and its variation, or enter weekly or daily sales totals (or import a CSV) and let the app work out the average and the variation. The Plan tab shows what to order today and how much, which items are out of stock, and which are above their maximum. Quantities are rounded up to the pack multiple and are never below the supplier minimum. The Order list groups the suggestions by supplier for printing or export. The Service level tab shows how much extra stock a higher service level needs.

The formulas are stated in the app: safety stock is z times the square root of ((lead time plus review period) times the daily variation squared, plus average daily demand squared times the lead time variation squared), where z is the normal quantile for your service level; the reorder point is average daily demand times lead time plus safety stock.

What is inside:

• Items, Sales history, Plan, Order list, Service level, Settings and Start here tabs
• Continuous review (order when stock plus on order reaches the reorder point) or periodic review (order up to a level at each review)
• CSV import of items and sales history, CSV export, JSON backup, print
• A worked example with invented figures

Who it is for: cafes, groceries and shops with tens to a few hundred items.

What it is not: the formula assumes demand is roughly normal and independent from day to day. Promotions, seasons (Ramadan, Eid, summer) and bulk orders break that, so use a history of normal trading or adjust by hand. A service level is a target, not a guarantee. It does not model cash or financing.

How it differs: the Reorder Point and Cash Conversion Planner App in the catalogue also covers cash cycle and growth funding and takes demand variation as a figure you enter. This app stays on stock, calculates variation from your sales history, handles lead time variation and review periods and groups orders by supplier. The Stock Count Sheets and Reorder Planner is an Excel file.

Tested: z values, safety stock, reorder points, order-up-to levels, order quantities with pack and minimum rounding and plan statuses were compared with a separate Python implementation on randomised items and histories, 9,897 values, with no differences. 99 scripted browser checks cover every tab, validation, CSV import, backup restore, print and the 375 and 1280 pixel layouts, with no console errors. Browser tests ran in Chromium and WebKit; Firefox, a real phone, a real printer and a real scanner were not available, so they were not tested.