Inventory Turnover Calculator — Methodology

Step-by-step calculation

Calculate how many times per year you turn your inventory and how long average stock sits before sale.

1. 1

   Enter annual COGS

   Cost of goods sold for the year — from your P&L.

2. 2

   Enter beginning and ending inventory

   Inventory values at the start and end of the period — from balance sheets.

3. 3

   Read the ratio and days

   Compare against the industry benchmark shown in the third result card.

Assumptions and overrides

Uses (Beginning + Ending) / 2 for average inventory — the standard formula but inaccurate for highly seasonal businesses. For seasonal operations, average 12 monthly inventory snapshots instead. Industry benchmarks reflect approximate medians and vary by business model within each category (e.g. fast-fashion retail turns 15-25× while traditional apparel retail turns 4-8×).

Every region default on the calculator is editable. If your effective rate, fee, or threshold differs from the headline figure shown, type your own number into the field — the calculator recomputes instantly without leaving this page.

Review cadence and corrections

This methodology and the underlying rate defaults are reviewed at least annually, and immediately following any change to the headline rate from IRS, HMRC, or SARS. Every substantive update is recorded on the public changelog. Spotted an error? See the corrections policy for how to report it.

See the full editorial policy for the standards every page on BusCalcTools is held to.