What is a reorder point?

The reorder point is the stock level at which the next purchase order should be placed. It combines the demand you expect during supplier lead time with any safety stock you want to keep in reserve.

Why is safety stock added on top of lead-time demand?

Lead-time demand estimates what you expect to use while waiting for delivery. Safety stock is the extra buffer you choose to carry in case demand runs hotter than normal or the supplier takes longer than usual.

How does weekly usage work here?

If you enter weekly usage, the calculator divides that figure by 7 to get a daily rate for lead-time demand and all day-based timing outputs. The page keeps the weekly label visible so the conversion is easy to audit.

What does “Reorder now” mean?

It means current stock is already at or below the calculated reorder point. That does not mean you are out of stock today; it means the remaining stock is no longer above the threshold you set for covering lead time plus safety stock.

What does this calculator not do?

It does not choose an order quantity, optimize carrying cost, forecast seasonality, or guarantee zero stockouts. It is a straight-line timing estimate from the usage, lead time, safety stock, and stock-on-hand assumptions you enter.

BUSBusiness

Reorder Point Calculator

Estimate when to place the next inventory order from your average usage, supplier lead time, safety stock, and current stock on hand. See the reorder threshold, whether you should reorder now, and how many days remain before you hit that threshold or stock out.

Average usage

Usage entered per

Supplier lead time

Safety stock

Current stock on hand

Try an example

Reorder status

Reorder in 1.3 days

Current stock is still above the threshold. The timing estimate assumes usage stays steady until the next order is placed.

Reorder point

80 units

Days until reorder

1.3 days

Days until stockout

7.9 days

Buffer above reorder point

15 units

This is an estimate from the assumptions you enter. Real demand spikes, supplier delays, and stock inaccuracies can still cause earlier or later stockouts.

Stock position barScale max: 109.25

Reorder zoneSafe buffer

Current stock

Reorder point

Safety stock

How It Works

Formula

D_{\text{lead}} = u_d \times L

ROP = D_{\text{lead}} + S

t_{\text{reorder}} = \frac{C - ROP}{u_d}

t_{\text{stockout}} = \frac{C}{u_d}

Where

$u_d$: Average usage per day after any weekly-to-daily conversion(units/day)
$L$: Supplier lead time in days(days)
$D_{\text{lead}}$: Units expected to be used during lead time(units)
$S$: Extra buffer you want left after covering lead-time demand(units)
$ROP$: Lead-time demand plus safety stock(units)
$C$: Units currently on hand(units)

First convert usage to a daily rate when needed. Lead-time demand is that daily rate multiplied by lead time in days. Add safety stock to lead-time demand to get the reorder point.

Frequently Asked Questions

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