Sell-Through Rate Explained: The Shopify Metric You're Probably Ignoring

If you had to pick one number that reveals how healthy your inventory is, sell-through rate would be a strong candidate.

Sell-through rate (STR) measures the percentage of your inventory that you sold during a given period. It is a simple ratio, but it answers one of the most important questions in retail: am I actually selling what I bought?

Shopify includes a basic version of this metric in its "Percentage of inventory sold" report, but most merchants either do not look at it or do not understand how to use it. That is a missed opportunity.

What sell-through rate is

The formula is:

Sell-Through Rate = (Units Sold / Units Available at Start of Period) x 100

If you started the month with 500 units of a product and sold 150, your sell-through rate is 30%.

A high STR means you are moving inventory efficiently. A low STR means stock is sitting. The metric is most useful when tracked over consistent periods (weekly, monthly) and compared across products.

What good sell-through looks like

Benchmarks vary by product type and industry, but some general guidelines:

Above 80% monthly is excellent. You are selling through most of what you stock. The risk here is actually too high: you may be frequently stocking out and losing potential sales. If your STR is this high, you probably need more inventory.

40-80% monthly is healthy for most product categories. You are moving stock at a reasonable pace without excessive overstock.

Below 40% monthly is a warning sign. You have more stock than demand justifies. Some of this inventory may be heading toward dead stock territory.

Below 20% monthly is a problem. Either you dramatically over-ordered, demand has dropped, or the product is not connecting with customers. Action is needed: discounts, bundles, or discontinuation.

Remember that these are monthly benchmarks. Seasonal products will have wildly different STRs depending on the time of year. A winter coat with a 10% STR in July is not necessarily a problem.

Why STR matters more than raw sales numbers

Raw sales numbers tell you what sold. Sell-through rate tells you how efficient your inventory investment was.

Consider two products:

Product A sold 1,000 units last month from an opening stock of 1,200. STR: 83%. Product B also sold 1,000 units last month, but from an opening stock of 5,000. STR: 20%.

Both had identical unit sales, but Product B has 4,000 units of excess inventory consuming warehouse space and cash. STR makes this visible in a way that raw sales figures do not.

STR also helps with purchasing decisions. If a product consistently shows 90%+ sell-through, you are probably under-ordering and should increase your next purchase quantity. If it consistently shows 25% sell-through, you are over-ordering and should cut back.

How to calculate STR in Shopify

Shopify's "Percentage of inventory sold" report does something similar to STR but has some quirks. It uses the starting quantity for the selected period and shows what percentage was sold. Restocking during the period can produce odd numbers (over 100% sell-through if you restocked and sold through the restock).

For a cleaner calculation:

Step 1: Note your beginning inventory for each product at the start of the period (export the inventory list on the first day of the month).

Step 2: At the end of the period, pull your sales data for units sold by product.

Step 3: Divide units sold by beginning inventory and multiply by 100.

If you restocked during the period, you have two choices: use only the beginning inventory as your denominator (simplest), or add the restocked units to the denominator (more accurate but more complex).

For ongoing tracking without manual exports, Stockful calculates sell-through rates automatically at the product and location level, using the daily inventory snapshots it captures.

How to use STR in practice

Identify under-performers before they become dead stock. Any product with a sell-through rate below 20% for two consecutive months deserves investigation. Is it priced too high? Is it not getting visibility on your site? Is demand simply gone?

Validate purchasing decisions. After you receive a new shipment, track the sell-through rate over the next 30-60 days. If it is lower than expected, adjust your next order quantity downward.

Compare products within categories. If you sell 20 different t-shirt designs, STR tells you which designs are resonating and which are not. Double down on the winners and phase out the losers.

Measure promotional effectiveness. Run a sale on a slow-moving product and watch how STR changes. If a 20% discount moves STR from 15% to 60%, the promotion worked. If it barely moves, the product has a deeper problem than pricing.

Track seasonal patterns. By measuring STR monthly for a full year, you build a picture of when each product peaks and valleys. This is invaluable for planning next year's purchasing.

STR and your other inventory metrics

Sell-through rate works best alongside a few other metrics:

ABC analysis tells you which products matter most. STR tells you how efficiently you are stocking them.

Inventory velocity (turnover) gives you the annual view. STR gives you the granular period-by-period view.

Days of supply tells you how long current stock will last at the current sales rate. STR tells you what percentage of stock moved in a past period.

Together, these metrics give you a complete picture of inventory health. Individually, each one tells only part of the story.

Start tracking it this week

If you are not measuring sell-through rate today, start with a simple monthly calculation for your top 20 products. You will almost certainly discover products you are over-stocking and products you are under-stocking.

That discovery alone is worth the ten minutes it takes to set up the calculation.

A note on restocking and STR accuracy

One nuance that trips merchants up: restocking during the measurement period skews the numbers. If you started the month with 200 units, received 300 more mid-month, and sold 350, your STR calculation depends on how you define "units available."

The simplest approach is to use beginning inventory only. Your STR would be 350/200 = 175%, which tells you that you sold more than your starting stock (good velocity, but hard to compare against other products).

A more useful approach is to use beginning inventory plus any units received: 350/500 = 70%. This gives you a cleaner picture of how much of all available stock moved.

Pick one method and use it consistently. The trend over time matters more than the absolute number.

Stockful calculates sell-through rates automatically for every product and location in your Shopify store. Get started free at [stockful.app](https://stockful.app).