The Hesapstan reorder point calculator is designed to calculate the inventory level at which a new replenishment order should be triggered, from average daily demand, supplier lead time and safety stock, more clearly. It is built for a business that wants to know when to reorder without running out of stock or holding too much of it: the inputs are average daily demand, lead time and safety stock, and the outputs are the expected demand during lead time, the exact and whole-unit trigger level, safety stock's share of that level, and its coverage in days. The tool's main limitation is that it assumes the average demand and lead time you enter remain realistic and representative — it does not forecast demand or compute a statistical safety buffer. The result is a replenishment TRIGGER, not an answer to how much to order.
What this calculator computes
The reorder point is the on-hand inventory level that should trigger a new replenishment order. It covers both the demand expected during the supplier lead time and the safety stock held against demand or delivery variability.
- Expected demand during lead time (average daily demand × lead time).
- The safety stock quantity used.
- The exact theoretical reorder point, which may be fractional.
- A whole-unit reorder trigger for indivisible inventory items, rounded up.
- Safety stock’s share of the trigger level and its coverage in days.
- No supplier API, no live stock integration, no demand forecast, no economic order quantity (EOQ).
Reorder point and economic order quantity (EOQ) are different concepts. This tool computes only the inventory level at which to reorder (when); it does not compute how many units to order at a time (how much) — that is EOQ.
What is lead-time demand?
Lead-time demand is the amount expected to sell between the moment you place an order and the moment the goods reach you. Your on-hand stock has to cover demand throughout that window until the new order arrives.
The larger the average daily demand and the longer the lead time, the larger the quantity expected to be consumed during that window — which is why both are the reorder point's core components.
What is safety stock, and why hold it?
Safety stock is the extra buffer you want on hand in case actual demand runs higher than average, or a supplier delivery is delayed. This tool takes safety stock as YOUR OWN input; it does not estimate it with any statistical method.
A business that wants to derive safety stock from a service-level probability or a normal-distribution method can run that calculation separately and bring the result here as an input.
How the reorder point is calculated
Expected demand during lead time is average daily demand multiplied by the lead time: Lead-Time Demand = Average Daily Demand × Lead Time.
The reorder point is that demand plus safety stock: Reorder Point = Lead-Time Demand + Safety Stock. Safety stock coverage in days is safety stock divided by average daily demand.
Worked example
Average daily demand 20 units, lead time 5 days, safety stock 30 units. Lead-time demand = 20 × 5 = 100. Reorder point = 100 + 30 = 130 — a whole number here, so the exact and whole-unit figures coincide. Safety stock coverage = 30 / 20 = 1.5 days.
Now take average daily demand 7, lead time 2.3 days, safety stock 5: lead-time demand = 7 × 2.3 = 16.1; reorder point = 16.1 + 5 = 21.1. For an indivisible product, this means reordering when stock falls to 22 units; at 21 units, part of the safety buffer is already uncovered.
Reorder point versus order quantity (EOQ)
The reorder point answers "when"; economic order quantity (EOQ) answers "how much". EOQ balances the cost of placing an order against the cost of holding stock to determine how many units to order at a time.
This calculator returns only the trigger inventory level. How many units to order at a time is outside its scope — EOQ is a separate calculation.
Why the result is a trigger, not an order amount
The reorder point only signals "place an order now"; it does not determine how many units to order. That decision depends on separate factors — supplier minimum order quantities, volume discounts, warehouse capacity, or EOQ.
Divisible versus indivisible inventory items
For items sold by the unit (boxes, parts, packs), the whole-unit trigger, rounded up, is the meaningful figure. For divisible items measured by weight or volume (kilograms, liters), the exact theoretical value can be used directly — no rounding is needed.
What happens if lead time or average demand changes?
As lead time lengthens or average daily demand rises, lead-time demand — and with it the reorder point — rises too. If a supplier changes, a season shifts, or demand changes on a lasting basis, recalculate with the updated figures.
This tool performs a point-in-time calculation; it does not update automatically when average daily demand or lead time changes.
The limitation of using an average
This tool uses a single average daily demand figure; real demand fluctuates day to day above and below that average. Safety stock exists to absorb that fluctuation, but this tool does not size the fluctuation itself (standard deviation, service-level probability) — you determine the safety stock quantity directly.
What this tool does not include: forecasting and service-level methods
Producing a demand forecast from historical sales data, computing a statistical safety stock under a normal-distribution assumption, or sizing safety stock to hit a specific service level (e.g. 95% in-stock probability) are outside this tool's scope. A business using those methods can carry the result here as the safety stock input.
Use in Turkey and internationally
You may enter demand and stock quantities consistently in any unit (units, boxes, kilograms); the formula is universal and not specific to any country. What matters is that average demand, lead time and safety stock all use the same unit.
The tool adds no Turkey-specific or country-specific inventory accounting, customs process, or import lead-time assumption; you enter the real lead time — domestic or from an overseas supplier — yourself. When sourcing internationally, customs and shipping time should be included in the lead time you enter.
Which inputs are rejected
- Average daily demand of zero or below is rejected — coverage days are undefined at zero demand.
- A lead time of zero or below is rejected — it would not represent a real delivery delay.
- Negative safety stock is rejected; zero is valid (no buffer held).
- A non-numeric or non-finite value is rejected and clears any previous result.
- Average demand and lead time may be entered as decimals whenever that is operationally realistic.
Frequently Asked Questions
Is the reorder point the same as the economic order quantity (EOQ)?
No. The reorder point is the inventory level at which to place an order. Economic order quantity is how many units to order at a time. This tool computes only the former.
Does this calculator estimate my safety stock for me?
No. You enter the safety stock quantity yourself; the tool does not estimate it from a statistical model such as a service-level probability or a normal-distribution method.
Why is the whole-unit result always rounded up?
Rounding down would leave part of the safety buffer uncovered. Rounding up gives the first whole unit that fully covers both the expected lead-time demand and the safety stock.
Does the result stay valid if demand or lead time change?
The result assumes the average demand and lead time you entered remain representative. If either changes materially, recalculate with the updated figures.
Should I use the whole-unit result for divisible stock like kilograms or liters?
Not necessarily. The whole-unit rounding is for unit-based, indivisible products. For weight- or volume-based divisible inventory, you can use the exact theoretical value directly.
Does this tool forecast demand?
No. It uses the average daily demand and lead time you enter as given; it does not project future demand from historical sales data.