The two components that make up your trigger, computed from the inputs above. Lead-time demand carries you through the supplier wait; safety stock is the cushion left when the order lands. Order the moment on-hand stock hits the total.
Component
How it is found
Units
Demand during lead time
10/day × 7 days
70
Safety stock buffer
Held against demand and lead-time variability
20
Reorder point ◀
Lead-time demand + safety stock
90
Estimates only — not financial, tax, or professional advice.
Calculated in your browser — the numbers you enter are never sent to our servers.
What it calculates: Reorder Point, Demand During Lead Time, Safety Stock.
Order when stock falls to this number, whenever that happens
A reorder point triggers on quantity rather than on the calendar. When stock drops to the level computed here, the replenishment order goes out — which is why it adapts automatically to a week of unusually strong sales, and a fixed monthly ordering schedule does not.
Reorder point = (average daily demand × lead time) + safety stock
The level is demand during lead time plus safety stock. Sell 40 a day with a 10-day lead time and you need 400 units just to survive the wait, before any buffer for the days that go wrong.
It ends when stock is sellable, not when the supplier ships
Lead time is the full cycle: placing the order, the supplier producing it, transit, customs where relevant, and receiving and putting away at your end. Counting only the supplier’s stated production time routinely understates it by a week or more.
It is also variable, and the variation matters more than the average. A supplier averaging 14 days but occasionally taking 25 needs a reorder point built around the bad case, which is what safety stock is for.
Demand during lead time is an average, and averages are exceeded
If you set the reorder point to exactly average demand during lead time and carry no safety stock, you will run out on roughly half of all cycles — every time demand or lead time lands above its mean.
The safety stock calculator sizes that buffer from how much demand and lead time actually vary. Feeding its answer in here is what turns a theoretical reorder point into one that holds up.
Steady demand, one supplier, and stock you can actually see
The calculation assumes demand is reasonably steady through the lead time. Sharply seasonal products need the reorder point recomputed for the season rather than set once from an annual average.
It also assumes your stock figure is accurate. A reorder point is only as good as the inventory count behind it, and shrinkage, miscounts and stock committed to unshipped orders all mean the system thinks you have more than you can sell.
Frequently Asked Questions
What is the difference between reorder point and safety stock?
Safety stock is the buffer you hold to cover surprises in demand or delivery. The reorder point is the broader trigger: it equals the demand expected during the lead time plus that safety-stock buffer. Safety stock is one input to the reorder point, not the same thing.
Should safety stock be included in the reorder point?
Yes. Without it, the trigger only covers average demand during the lead time, leaving nothing to absorb a busy week or a late shipment. Including safety stock is what protects you against running out during normal variability.
How do I find my average daily demand?
Take the units sold over a recent representative period and divide by the number of days. Selling 300 units in 30 days is an average of 10 units a day. Use a window that reflects current demand rather than an unusually slow or busy stretch.
What lead time should I use?
Use the realistic time from placing an order to having sellable stock on the shelf, including supplier processing, transit, and any receiving or inspection. If lead times swing, use a longer figure or raise safety stock to stay protected.
Does a higher reorder point mean more inventory cost?
It can. A higher trigger means you reorder sooner and tend to carry more stock, which raises carrying cost. The aim is a point high enough to avoid stockouts but not so high that capital sits idle on the shelf.
How often should I update the reorder point?
Review it whenever demand trends shift, a supplier changes its lead time, or you adjust your safety-stock policy. Seasonal businesses often recalculate before each peak so the trigger matches the demand they actually expect.
Sources & References
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
Results are estimates for planning and analysis based on the figures you enter. They are not accounting, tax, or financial advice — verify with your own records and a qualified professional before making decisions.
Built and maintained by Jay Sudha, who runs a rice mill and trading business in Kashipur, India, and works with pricing, margins, working capital and bank credit as part of it.
Published the calculator with its formula, worked example, assumptions, limitations and a bespoke guide, and added an automated formula test suite covering it.
Tested the reorder point as demand during lead time plus safety stock, recomputed independently from the rate and the lead time.
Tested that a zero lead time leaves only the safety buffer, and that the point scales linearly with both demand and lead time.
Frequently Asked Questions now show on the page: 6 answers, checked in a page-by-page audit.
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