Calculators

Free inventory calculators. The first three plan a reorder, in order; the last two check whether your stock pays its way. Each explains the idea, shows the formula, and lets you try your own numbers.

1. 1

   Lead time

   How long do my orders really take?

   You're deciding when to order and need the real wait, not the supplier's quote.

   Formula: Days from placing the order to the stock being ready to sell.

   Example: The planned stages add up to 51 days. Across 4 past orders it really took 41 days on average, 44 at the longest.

   Try it with your numbers
2. 2

   Safety stock

   How much buffer should I hold?

   Sales or deliveries vary, and you want a cushion so a busy week or a late ship doesn't empty the shelf.

   Formula: Service-level factor × how much daily sales vary × √ lead time.

   Example: At a 95% service level: 1.65 × 4 × √30 = 37 units, rounded up.

   Try it with your numbers
3. 3

   Reorder point

   When should I reorder?

   You want the stock level that should trigger the next purchase order.

   Formula: Daily sales × lead time + safety stock.

   Example: 12 a day × 30 days + 90 safety stock = 450 units.

   Built from steps 1 and 2.

   Try it with your numbers

Also check

• Inventory turnover

  Am I holding too much stock?

  You want to see how quickly the money tied up in stock comes back as sales.

  Formula: Cost of goods sold ÷ average inventory value.

  Example: $240,000 ÷ $60,000 = 4× a year, about 91 days on the shelf.

  Try it with your numbers

• Profit margin

  What does one order really earn?

  You're choosing which products deserve more stock and more ad spend.

  Formula: Price − product cost − shipping − fees − ads.

  Example: $40.00 − $12.00 − $7.00 − $2.40 − $10.00 = $8.60 per order.

  Try it with your numbers