The reorder point is the stock level that triggers your next purchase order: (average daily sales x supplier lead time) + safety stock. When on-hand inventory touches that number, you order, so the replenishment lands just before you would have run out. It is the simplest piece of inventory math with the highest payoff, and the most common one to compute correctly and then forget to watch.
The formula, worked through
A SKU sells 6 units a day on average. Your supplier takes 15 days from order to sellable stock. You hold 20 units of safety stock for surprises.
Reorder point = (6 x 15) + 20 = 110 units.
At 110 units you place the order; during the 15-day wait you expect to sell 90, landing you at ~20 (your buffer) when new stock arrives. Demand spike or supplier delay eats into the 20 instead of into your listings.
The three inputs deserve honesty:
- Average daily sales: use a window that reflects now (30 days for steady SKUs, shorter and weighted for trending ones). Include ALL channels, more below.
- Lead time: measured reality, not the supplier’s brochure. Include your own receiving time, stock in a box in the corridor is not sellable.
- Safety stock: sized deliberately, the full method here, not a vibes number.
The multichannel correction
Selling from one pool on several channels changes the arithmetic in one important way: daily sales means combined velocity. A SKU doing 2/day on your store, 3/day on Amazon, and 1/day on eBay is a 6/day SKU. Computing reorder points per channel triples your math and understates every number.
The channel mix also shifts, a SKU that goes viral on one marketplace changes its combined velocity overnight, which silently moves the correct reorder point. This is why static spreadsheet reorder points decay: the formula stays right while its inputs walk away.
From formula to system
A reorder point nobody watches is a stockout with paperwork. The operational version:
- Compute per SKU from live cross-channel sales, refreshed continuously.
- Alert when touched: the SKU crossing its trigger should come to you, not wait to be found.
- Sanity-check with days of cover: reorder point in units and days of cover in time are the same decision from two angles; when they disagree, an input is stale.
- Order to a target, not just “some more”: enough to restore your intended cover (often 30-60 days for steady SKUs) without parking cash on the shelf, turnover tells you if you overshoot chronically.
Unifystock supplies the inputs and the watching: per-SKU velocity across every connected channel, days-of-cover and stockout forecasts, and low-stock alerts at thresholds you set, so the trigger fires itself.
Common questions
How is reorder point different from safety stock?
Safety stock is a quantity you hold for surprises; the reorder point is the trigger level that incorporates it. Safety stock answers “how much cushion”; reorder point answers “when to order”.
What if my supplier’s lead time varies a lot?
Use the longer realistic lead time in the formula or move the variance into safety stock, one place or the other must absorb it. Measured lead times per supplier beat promises.
Should seasonal products use the same formula?
Same formula, forward-looking inputs: entering the season, use expected in-season velocity, not the off-season trailing average, or the trigger fires far too late.
Can I set reorder points for made-to-order goods?
Yes, on components and production slots rather than finished goods. The formula is the same; the “stock” is capacity.
Let the trigger watch itself
Live counts across every channel from $49/month with unlimited orders, and per-SKU velocity with reorder signals and their alerts on the plans above. See pricing.