What Is the Reorder Point Formula?
The reorder point formula tells you the exact stock level at which to place your next order: (average daily sales × lead time) + safety stock. Here's how to find your reorder point — and how AI keeps it accurate as demand shifts.
Reorder too late and you stock out; reorder too early and you tie up cash. The reorder point formula is the simple math that gets the timing right — if the numbers feeding it stay fresh.
Key Takeaways
- Reorder point = (average daily sales × lead time) + safety stock.
- Use real, current inputs: recent sales velocity and true end-to-end lead time.
- A static reorder point goes stale fast — demand and lead times drift constantly.
- AI agents recompute reorder points per SKU daily and draft the purchase orders, so you scale without spreadsheet work.
The reorder point formula, explained
The reorder point (ROP) is the inventory level at which you should place a new purchase order so replenishment arrives before you run out. The formula is: Reorder point = (average daily sales × supplier lead time in days) + safety stock.
Worked example
You sell 12 units a day, your supplier takes 14 days to deliver, and you hold 50 units of safety stock. Your reorder point is (12 × 14) + 50 = 218 units. The moment stock on hand drops to 218, you order — the 168 units you'll sell during the lead time are covered, and the 50-unit buffer absorbs surprises.
How to find your reorder point step by step
Each input comes from data you already have — the discipline is keeping it current:
- Average daily sales: units sold over the last 30–90 days ÷ days in the period. Use a window long enough to smooth spikes but short enough to reflect current demand.
- Lead time: the real elapsed days from placing a purchase order to stock being sellable — including production, shipping, and receiving, not just the supplier's quoted time.
- Safety stock: the buffer against demand spikes and late deliveries. A practical starting point is (maximum daily sales × maximum lead time) − (average daily sales × average lead time).
- Recalculate regularly: a reorder point set in January is wrong by June. Sales velocity and lead times drift, and the formula is only as good as its inputs.
Where the static formula breaks down
The formula assumes steady demand and reliable lead times — and real stores have neither. Seasonality, promotions, viral spikes, and supplier delays all move the true reorder point week by week. A spreadsheet ROP calculated quarterly is often stale the day after you set it.
This is why fast-growing stores pair the formula with safety stock and reorder point automation and inventory forecasting: the math stays the same, but the inputs update continuously from live sales data instead of a snapshot.
How to use an AI agent to scale your operation
Recalculating reorder points across hundreds of SKUs is exactly the kind of high-frequency, low-glamour work an AI agent does better than any human. The AI CEO Autopilot connects to your live store data and recomputes every product's daily velocity, lead time, and safety stock continuously — so each SKU's reorder point is always current, not a quarterly estimate.
It then acts on the math: days-to-stockout countdowns per product, urgency-ranked reorder alerts, revenue-at-risk totals so you fix the most expensive gaps first, and draft purchase orders raised at the right moment for you to approve. That's how ecommerce businesses scale operations without scaling headcount — the AI handles the relentless recalculation and monitoring, and you make the final call on every order.
Let the AI COO handle it for you
AI CEO runs the operational side of your store — stock, fulfilment, and the daily decisions that keep orders moving — so the problems in this article get caught before they cost you.
- Monitors inventory, orders, and supplier timing in real time and reorders before you run out.
- Surfaces a daily briefing of what needs attention, ranked by impact on revenue.
- Handles the routine calls automatically and escalates the judgement calls to you.
Frequently Asked Questions
What is the reorder point formula?
Reorder point = (average daily sales × supplier lead time in days) + safety stock. It's the stock level at which you should place your next purchase order so replenishment arrives before you sell out.
How do I find my reorder point?
Calculate your average daily unit sales over the last 30–90 days, multiply by your real lead time in days, then add safety stock. Example: 12 units/day × 14-day lead time + 50 safety stock = a reorder point of 218 units.
What's the difference between reorder point and safety stock?
Safety stock is the buffer quantity you hold against surprises; the reorder point is the trigger level that includes that buffer plus the stock you expect to sell during the lead time. Safety stock is one input to the reorder point formula.
Can the reorder point be automated?
Yes. AI inventory tools recalculate each SKU's reorder point continuously from live sales and lead-time data, then alert you or draft a purchase order when stock hits the trigger — removing the manual spreadsheet cycle entirely.
Keep Reading
Safety Stock & Reorder Points
How the buffer and the trigger work together in practice.
Inventory Forecasting Guide
Forecast demand so your reorder inputs stay accurate.
Inventory Forecasting Software
Days-to-stockout and reorder timing from your live store data.
AI COO for Shopify
The operations brain that watches stock and reorders for you.
Put Your Store on Autopilot
AI CEO runs marketing, operations, and finance for your Shopify store — from the same live data, with you in control.