Reorder point: how to know when to reorder each item

A reorder point is the stock level that tells you “order this now”, set so the new delivery arrives before you run out. Get it right and an item sits quietly until it hits its number, then it lands on the next order, no memory required.

This applies to any stock you reorder regularly — packaging, cleaning supplies, spare parts, office basics. Below: the formula, a worked example, how reorder point relates to par level and minimum stock level, and how to set and revisit the numbers.

The reorder point formula

A reorder point has two parts: what you will use while waiting for the next delivery, plus a safety buffer for a slow delivery or a busy spell.

Reorder point = (usage rate × resupply wait time) + safety stock

• Usage rate: how much of the item you typically use per day or week.
• Resupply wait time: how long it takes from placing an order to having stock in hand.
• Safety stock: the cushion for delays or a busier-than-usual stretch.

No statistics needed. Rough numbers from recent weeks are good enough; adjust once you see how they behave.

A small worked example

Say your team uses 2 boxes of a packaging material a week, and the supplier takes 5 days to deliver.

Usage during the wait: 2 boxes ÷ 7 days × 5 days ≈ 1.4, rounded up to 2. Add a safety stock of 1 box for a late delivery.

Reorder point = 2 + 1 = 3 boxes. When stock drops to 3, place the order — nothing more than the two numbers added together.

Par level, reorder point and minimum stock level

The three terms get mixed up constantly. Here is what each one answers:

Term	Question it answers	In the example above
Reorder point	When do I place the next order?	3 boxes
Par level	How much should be on the shelf after restocking?	e.g. 10 boxes: order par minus what is left
Minimum stock level	What is the floor I never want to go below?	Usually the safety stock alone, e.g. 1 box

Many teams use “reorder point” and “minimum stock level” as the same number, which is fine as long as everyone means the same thing by it. The useful distinction: the minimum is the floor, and the reorder point sits a little above it on purpose, so there is time to order before you hit the floor.

Build a par level inventory sheet

A par level inventory sheet is just a list, one row per item you reorder, with the numbers above next to it:

• Item name and the unit you count in (box, case, bag)
• Usage rate, resupply wait time, safety stock
• Reorder point and par level
• Where it’s stored

Start with the items that hurt most when they run out or that you reorder often. A shelf of rarely used spares can stay informal.

Setting and revisiting your thresholds

Set the first numbers from a normal recent week, not a busy one, then watch what happens:

• Reordering earlier than planned? Usage rose or the wait grew — raise the reorder point.
• Stock still high when the next delivery lands? The numbers are too generous — lower them.
• Revisit after a supplier’s lead time changes, a season or promotion shifts usage, or any stockout.

Treat thresholds as a setting you tune a few times a year, not a constant.

When the simple way is still fine

If you reorder a handful of items, one person always orders, and they already have a feel for when something is running low, a mental reorder point works fine. Writing it down earns its keep once more than one person restocks, once an item has caught you out, or once someone else needs to place the order without asking around first.

Where Tana fits

Tana is a shared inventory app for teams, and it covers the “tell me when to reorder” part of this.

Set a low-stock threshold per item — your reorder point — plus a team default for items you haven’t set individually. When stock reaches it, Tana raises a low-stock alert on every plan: home page, email, push, and optionally a Slack channel. A filter shows only what’s running low. Each item has a “how to reorder” note for the supplier, usual order quantity or par level, plus shop links to search online stores. Record usage with a tap, and the history of who took what and when is most of what you need to judge a usage rate.

Tana doesn’t calculate a reorder point or place orders automatically; you set the threshold, and the alert tells you when you’ve reached it.

Frequently asked questions

What is the formula for a reorder point?

Reorder point = (usage rate × resupply wait time) + safety stock. Multiply how much you use per day by how many days delivery takes, then add a buffer for delays or busy spells.

What’s the difference between a reorder point and a par level?

The reorder point is when you order; the par level is the amount you top back up to. When an item hits its reorder point, order the par level minus what is still on the shelf.

Is minimum stock level the same as reorder point?

Often used that way, but it’s cleaner to treat the minimum as the floor you never want to drop below, with the reorder point set slightly above it so there’s time to order first.

How do I know if my reorder point is set correctly?

If you’re placing rush orders or running out before delivery arrives, raise it. If stock is still high when the next delivery lands, lower it. Check again whenever lead times or usage change.