What is SKU velocity and why does it matter?
SKU velocity is the average units sold per day for a specific SKU, usually measured over a rolling 30-day window. It drives every downstream inventory decision: PO size, safety stock, days of cover targets, and IPI score. A SKU whose velocity drops 30% for two weeks is either losing search rank or facing seasonality.
Jul 26, 2026 · 3 min read
How to measure it
Use a 30-day rolling window for stable SKUs. Use 14 days for launches or seasonal SKUs. Exclude days with stockouts to avoid biasing the average downward.
Velocity and category rank move together, so it helps to read units per day against best sellers rank on the same chart.
Why 30% is the alert threshold
Small daily variation is normal. A sustained 30% drop over 14 days almost always signals a real issue: lost keyword rank, a new competitor, a price change, or seasonality. It is worth investigating within the week.
How velocity feeds decisions
PO size = velocity x lead time x safety factor. Days of cover = current inventory / velocity. Restock alerts fire at velocity x reorder-lead-time.
Frequently asked questions
Should I use 30-day or 90-day velocity?
30-day for planning, 90-day for benchmarking. 90-day misses recent trend changes.
How does velocity relate to sell-through?
Sell-through is a 90-day inventory turn ratio. Velocity is a daily unit rate. Both matter but for different decisions.
What causes velocity to drop?
Lost search rank, competitor launches, price increases, listing suppression, review score dropping below 4.0, or seasonality.
Does Nova track SKU velocity?
Yes. Nova shows daily and 30-day velocity per SKU in inventory monitoring.
See this in Nova
Nova surfaces this metric per SKU so you can act before your next monthly close catches it.
Try Nova free for 14 daysRelated questions
What is days of cover and how do I calculate it?
Days of cover = current on-hand inventory / average daily units sold. If you have 600 units on hand and sell 20/day, you have 30 days of cover. Set a target from lead time, demand variability, safety stock, and storage costs.
What is a good sell-through rate on Amazon?
Amazon's sell-through rate is units shipped in the last 90 days divided by average inventory over the same period. Above 3.0 is strong (inventory turns 12x/year). 2.0 to 3.0 is healthy. Below 1.0 usually means overordered units and forecasts long-term storage fees within a quarter.