How to use this sell-through calculator
Sell-through rate is the share of available stock you actually sold in a period: units sold divided by units available, times 100. Enter three numbers and you get the rate, your daily run rate, and how many days the remaining units will last at the current pace.
- Units available = stock at the start of the period plus anything that arrived during it.
- 30 days is the standard window; shorter periods swing too hard to read.
- Watch the days-to-sell-out number: it is the bridge to your next reorder.
The sell-through formula
Sell-through rate = units sold ÷ units available × 100, measured over a fixed period, usually 30 days. Retailers built the metric to grade buying decisions: it asks whether the stock you committed to actually moves. A 100% rate is not the goal; it usually means you ran out and left sales on the table.
Reading the number: pace and runway
There is no universal good sell-through rate, so this calculator grades runway instead. Stock projected to sit past 180 days is heading into aged-inventory surcharge territory. A sell-out inside 30 days means the reorder should already be in motion, because a 35-day lead time will outlast your stock.
The healthy middle is wide on purpose. Fast sell-through with stockouts costs rank and reviews; slow sell-through costs storage and cash. Judge the number against your lead time on one side and the 181-day fee line on the other.
Worked example: 480 units sold from 1,400 available
Say you started the month with 1,400 units available and sold 480. Sell-through is 34.3%, the run rate is 16 units a day, and the remaining 920 units last about 58 more days. With a 35-day lead time, the reorder point arrives in roughly three weeks, not today.
- If pace doubles to 32 a day, the same 920 units last 29 days and the reorder is late.
- If pace halves to 8 a day, stock stretches 115 days: watch the 181-day fee line.
- Feed the daily rate into the reorder point calculator to time the next PO properly.
Sell-through vs inventory turnover
Sell-through is a period snapshot in units; turnover is an annual ratio in dollars. A 34.3% monthly sell-through and a 5.2× yearly turnover can describe the same product. Use sell-through to steer weeks, turnover to grade the year, and the same discipline drives both numbers up.
Frequently Asked Questions
What is sell-through rate?
Sell-through rate is the share of available stock sold in a period: sold ÷ available × 100. A 30-day window is the standard way to measure it.
What is a good sell-through rate?
There is no universal number; grade the runway instead. Stock lasting past 180 days risks aged-inventory surcharges, and a sell-out inside 30 days means reorder now.
Is a 100% sell-through rate good?
Usually not. It typically means you stocked out and lost sales. Rank and reviews suffer while the listing sits empty, which costs more than storage.
What counts as units available?
Stock at the start of the period plus arrivals during it. Leaving arrivals out inflates the rate and hides slow stock.
How is sell-through different from turnover?
Sell-through is a period snapshot in units; turnover is an annual ratio in dollars. Use sell-through to steer weeks and turnover to grade the year.
What period should I measure?
30 days is the standard. A single week swings with deals and stockouts; a quarter hides problems for too long.
How does sell-through connect to reordering?
The daily run rate it produces is a reorder point input. At 16 units a day and a 35-day lead time, you reorder while 920 units still look comfortable.
Does this work outside Amazon?
Yes. The formula is channel-agnostic retail math. Shopify, eBay, Etsy, and wholesale all measure sell-through the same way.