Reorder point and reorder quantity calculator
Enter one product's sales and stock. You'll get how many days it has left, when to reorder, and how many to order.
Order 45 now
It runs out in about 9 days, before a new order could arrive in 14.
- Sales per day
- 1.29
- Days left
- 9
- Reorder point
- 18 units
- Reorder amount
- 45 units
1.29 × (14 + 30) − 12 − 0 = 45
The same rules StockDigest runs for every product, every morning.
How the calculator works
Sales per day
Half the 28-day average plus half the 7-day average. Leave the 7-day box blank and it uses the 28-day pace alone.
Days left
In stock ÷ sales per day. If it's shorter than the lead time, the product sells out before a new order could arrive.
Reorder point
Sales per day × lead time, plus safety stock. When stock falls to this level, it's time to order.
Reorder amount
Sales per day × (lead time + days the order should last) + safety stock − in stock − on the way, rounded up.
Questions
What's the difference between the reorder point and the reorder amount?
The reorder point is the stock level that tells you to order: sales per day × lead time, plus any safety stock. The reorder amount is how many to order: enough to cover the lead time and the days the order should last, minus what you have and what's on the way.
Why blend the 28-day and 7-day averages?
The 28-day average is steady but slow to notice change. The 7-day average notices change fast but swings on one big order. Half of each catches a product that's speeding up without overreacting.
Should I add safety stock?
If a supplier is often late, or one big order can wipe you out, a small buffer helps. Raising the lead time a few days does the same job with one less number to track.
Does StockDigest use this formula?
Yes, the same rules, run for every product each morning, with 14 days of lead time and 30 days of cover to start. StockDigest doesn't add safety stock; give slow suppliers a longer lead time instead. How forecasts work