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Inventory & Operations

Inventory Turnover Calculator

See how often inventory turned during your reporting period and how many days of cost of goods sold it represents. Use opening and closing balances, or a more representative average from your records.

Which inventory balances do you have?

Switching modes clears your inputs and result.

Your numbers

USD

Use two endpoint balances for a simple average

Use COGS, not sales revenue. Use the same cost basis as inventory.

Inventory balance at the start of the COGS period.

Balance at the end of the same period. Seasonal peaks may be missed by these two snapshots.

Match the COGS reporting period: for example 90 for a quarter or 365 for a year.

Your own target for comparison. This is not an industry recommendation.

Use inventory and COGS at cost in USD for the same period. Money allows 2 decimals; period length uses whole days.

Your result

Inventory turns in this period

Compare the cost of goods sold with a representative average inventory balance.

Calculated on your device. Your numbers aren’t sent or saved.

No sign-up Private calculationsHow it’s calculated

The method

One inventory measure, expressed as turns and days

Divide cost of goods sold by average inventory at cost to get turnover for the period. Divide the period length by turnover to get days inventory outstanding (DIO), also called days sales in inventory. Opening and closing balances produce a two-point average; a separately calculated average can capture more of a seasonal cycle. The optional target compares inventory balances at unchanged COGS, not cash you are guaranteed to collect.

Two-point average inventory(Opening inventory + closing inventory) ÷ 2
Turnover for the periodCost of goods sold ÷ average inventory at cost
Days inventory outstandingDays in period × average inventory ÷ cost of goods sold
Inventory at target DIO(Cost of goods sold ÷ days in period) × target DIO

Example 1

Six turns in a year, with a 45-day comparison

Opening inventory of $80,000 and closing inventory of $120,000 average $100,000. With $600,000 COGS over 365 days, turnover is 6 times and DIO is 60.83 days. A 45-day target at unchanged COGS corresponds to $73,972.60 average inventory, $26,027.40 below the current average. That difference requires operational changes; it is not guaranteed cash release.

Average inventory
$100,000.00
Period turnover
6.00×
DIO
60.83 days

Example 2

A quarter is not a year

For a 90-day period, $100,000 COGS divided by $25,000 average inventory is 4 turns during that quarter. DIO is 90 ÷ 4 = 22.5 days. Calling those 4 turns an annual rate would change the meaning. This calculator reports the selected period and does not silently annualize it.

Period
90 days
Turnover in period
4.00×
DIO
22.50 days

Example 3

Seasonal stock: the same year can look very different

Five equally spaced snapshots are $100,000, $300,000, $500,000, $300,000 and $100,000. Their simple mean is $260,000; using only the opening and closing snapshots gives $100,000. Against $520,000 annual COGS, the five-point mean gives 2 turns and 182.50 days, while the endpoints give 5.2 turns and 70.19 days. The arithmetic is the same; the inventory sample changes the conclusion. A discrete snapshot mean still is not an exact time-weighted average.

Five-point average
$260,000.00
DIO from five points
182.50 days
DIO from endpoints
70.19 days

Before you calculate

Assumptions & limits

  • COGS and inventory use the same currency and cost valuation basis for the same reporting period. Revenue includes markup and is not a substitute for COGS. Amounts are USD labels without currency conversion.
  • The average inventory balance must be positive. Zero COGS gives zero turns and undefined DIO; it does not indicate that inventory sells instantly. Target inventory is unavailable when COGS is zero.
  • Opening and closing inventory are a simple two-point average. For seasonality or large receipts, use representative records to calculate an appropriate average and enter it directly. Do not assume a snapshot mean is the exact continuous-time average.
  • Money is nonnegative, no greater than $999,999,999.99, with up to two decimals. Period length is 1–3,660 whole days. An optional DIO target accepts 0.01–3,660 days. Targets are supplied by you; no industry benchmark is imposed.
  • Calculations preserve a half-cent opening/closing average and exact rational ratios until display rounding. Results use two decimals with midpoint ties away from zero. A displayed average rounded to cents can differ from the unrounded value used in the ratio.
  • Inventory targets hold the COGS rate constant and ignore operational constraints. Higher turnover is not automatically healthier: insufficient buffers, supplier delays and stockouts can harm sales. Compare like periods and service levels rather than treating one ratio as a verdict.

Keep in mind

Common mix-ups

Using sales instead of COGS

Inventory at cost and sales at selling price are different valuation bases. Use the cost of goods sold to avoid inflating the turnover ratio with markup.

Mixing quarterly COGS with 365 days

The days input must match the period covered by COGS. For a 90-day quarter, use 90 days.

Missing the seasonal inventory peak

Two low endpoint balances can hide expensive stock held between them. The seasonal worked example shows why the average basis matters.

Sources & calculation notes

ACCA — Working capital management

Explains inventory days and the cash operating cycle. Our examples independently illustrate period consistency and inventory sampling.

ACCA — Performance appraisal ratios

Supports the inventory period calculation and reading financial ratios in context. No universal industry-health cutoff is inferred.

Calculation and input rules checked: . Engineering validation; no professional accounting review is claimed.

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