Inventory Calculator

Know what your stock is worth and when to restock. Enter how many units you hold, what they cost and sell for, and how fast they move — you will see your inventory value at cost and at retail, how many weeks of stock you have left, and the reorder point to hit before you run dry.

Units in stock
Cost / unit ($)
Retail / unit ($)
Units sold / week
Restock lead time (weeks)

Your inventory

$240.00
Value at cost
$600.00
Value at retail
8
Weeks of stock
10
Reorder point

Your 40 units are worth $240.00 at cost and $600.00 at retail — about $360.00 of potential profit. At 5 sold per week you have roughly 8 weeks left; reorder once you drop to 10 units to cover the 2-week restock.

Reorder point by sales speed

Units sold / weekReorder point (2-week lead)
24 units
510 units
1020 units
2040 units

Reorder point = how fast you sell multiplied by how long restocking takes. Add a little extra if your supplier is slow or unpredictable.

Stock smarts

  • Track value at cost for taxes and at retail for sales potential.
  • Reorder at the reorder point, not when you hit zero.
  • Watch slow movers — cash tied up in dead stock cannot buy what sells.
  • Keep a small safety buffer for popular items and busy seasons.

Frequently asked questions

How do I value my inventory?

Multiply the units you hold by their cost for the value at cost, and by their selling price for the value at retail. The gap is your potential profit if it all sells.

What is a reorder point?

The stock level where you should reorder. It equals how many you sell per week times how many weeks restocking takes, so new stock arrives before you run out.

Should I value inventory at cost or retail?

Both. Cost value matters for taxes and cash tied up; retail value shows the sales still sitting on your shelf. Tracking both keeps decisions grounded.

How much stock should I keep?

Enough to cover sales through your restock lead time plus a small safety buffer. Too much ties up cash; too little risks stockouts during busy spells.

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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.