A reorder point that survives a real parts bin

A reorder point is three numbers

Average usage per week, lead time in weeks, and a buffer. Multiply the first two and add the third. That is the whole calculation, and it beats memory because memory reorders after the stockout.

The buffer is where judgment goes. A consumable from a supplier two hours away with steady usage barely needs one. A bar size with one supplier and a six-week lead time needs a real cushion, and you should be able to say out loud why you picked the number you picked.

Usage has to come from entries, not estimates

Nobody guesses weekly usage accurately. You get it from an issues log: item, quantity, date, and the job it went to. Six weeks of entries gives you a usable average, and it also tells you whether usage is steady or lumpy — which matters more than the average itself.

Lumpy usage does not want a bigger buffer as a first response. It wants the reorder point tied to the job that consumes it, which usually means buying to the job and holding a small floor quantity rather than carrying a large safety stock.

On-hand accuracy is the actual constraint

A perfect reorder point on a wrong on-hand quantity produces a stockout with paperwork. Receipts in, issues out, entered the day they happen. No barcodes required — a shared workbook and a rule about entering before the material moves is enough for most shops.

Then cycle count. Print a count sheet for one location, count it, record the variance, correct the balance. Rotate through locations so the whole stockroom gets counted over a quarter without ever shutting down for a physical inventory.

• Count the fastest-moving and highest-value items more often than the rest
• Record variances, do not silently overwrite — variances show you where the process leaks
• Correct the balance the same day you count, or the count was wasted

Review the numbers quarterly

Lead times move, usage moves, suppliers change. Reorder points set once and never revisited are the reason shops carry the wrong inventory: too much of what stopped selling and too little of what picked up. A quarterly pass over the items that stocked out or sat untouched is enough.

Also watch value on hand by category. It is the number that tells an owner how much cash is sitting on the racks, and it is the reason a reorder-point discipline pays for itself in something other than avoided expedite fees.

Where a system helps

The Inventory Control System keeps the item master, receipts and issues logs, cycle count sheets, and a filtered reorder report that does the comparison for you, so the buy list is a view rather than a weekly rebuild.