Free Slow Moving Inventory Calculator
Calculate sales velocity, months of supply, and possible excess inventory for one item — free, instant.
That's one SKU. What about the rest of your inventory?
Inventory Assassin analyzes your entire inventory file, identifies the products tying up the most cash, ranks what deserves attention first, and recommends what to do next.
Analyze My Entire Inventory →What this calculator tells you
How fast one item is actually selling, how many months its current on-hand quantity represents at that pace, and how many units (and how much cash) sit above what your target supply level calls for.
How the calculation works
Daily Velocity = Units Sold ÷ Period (days)
Monthly Velocity = Daily Velocity × 30
Months of Supply = Units on Hand ÷ Monthly Velocity
Possible Excess Units = Units on Hand − (Desired Months of Supply × Monthly Velocity)
If nothing has sold in the period, months of supply is undefined and the full on-hand quantity is treated as excess.
Example
100 units on hand, 30 units sold in the last 90 days, unit cost $10, desired 2 months of supply:
- Daily velocity = 30 ÷ 90 = 0.33/day → Monthly velocity ≈ 10/month
- Months of supply = 100 ÷ 10 = 10 months
- Target supply = 2 × 10 = 20 units → Possible excess = 80 units ($800)
How to interpret the result
Months of supply well beyond your target suggests either overbuying or a real slowdown in demand. A moderate markdown, bundling with a faster-moving item, or a multi-buy promotion can often restore a healthy pace without giving up much margin — see the guide below.
When this metric can be misleading
A short sales window can overstate or understate true velocity — a single large order in a 90-day window can make a genuinely slow item look fine, and a seasonal lull can make a healthy item look slow. Use a period long enough to smooth out one-off spikes.
What to do next
Read Slow-Moving Inventory: How to Spot It and What to Do for the fuller picture, including how slow movers differ from dead stock and when the right response changes.
Analyze your entire inventory
Slow movers are easiest to catch with a portfolio-wide view, not one SKU at a time. Inventory Assassin sorts your entire catalog by cash tied up and sell-through together. See the full inventory health guide →