The cash conversion cycle is the number of days between paying suppliers and receiving cash from customers: stock days plus debtor days less creditor days. Getting a figure you can trust depends on using consistent figures, stripping VAT out of debtors and creditors, and allowing for seasonality. It is shortened mainly by holding less stock and collecting faster, with supplier terms a smaller and riskier lever.

What does the cash conversion cycle measure?

ACCA’s technical article on working capital management describes the cash operating cycle, also known as the working capital cycle or the cash conversion cycle, as the number of days between paying suppliers and receiving cash from sales. It is calculated as inventory days plus receivables days less payables days. The longer the cycle, the more money is tied up in running the business day to day and the more funding is needed, usually from an overdraft or the owners.

The cycle is a measure of time, not of money, which is what makes it useful. A business can compare its cycle from one year to the next, or against similar businesses, even when its turnover has changed. Converting days back into pounds then shows how much cash a change in the cycle would release or absorb. This page concentrates on calculating the cycle accurately and on the levers that shorten it. The wider picture of liquidity, overtrading and supplier relationships is covered in working capital management.

How do you calculate stock, debtor and creditor days?

ACCA’s ratio analysis article sets out the three standard formulas:

  • Stock (inventory) days = stock divided by cost of sales, multiplied by 365.
  • Debtor (receivables) days = trade debtors divided by credit sales, multiplied by 365.
  • Creditor (payables) days = trade creditors divided by credit purchases (or cost of sales), multiplied by 365.

Each formula compares a balance with the flow that feeds it. Stock is used up through cost of sales, so it is compared with cost of sales rather than turnover. Debtors arise from credit sales, so cash sales should be excluded from the denominator where they are significant. Creditors arise from purchases, so purchases on credit are the better denominator where they are known; cost of sales is a proxy that can mislead when much of cost of sales is wages rather than bought in goods.

Which figures should you use?

Average or closing balances

ACCA notes that exam questions often provide only year end figures, which must then be used as a proxy for the average. In real accounts the year end is often a quiet point in the trading year, when stock and debtors are at their lowest, so a cycle worked out from closing balances can look better than the business experiences for most of the year. Where monthly management accounts exist, average the twelve month end balances instead.

Taking VAT out

Section 474 of the Companies Act 2006 defines turnover as amounts derived from the provision of goods and services after deducting trade discounts, VAT and other taxes based on those amounts. Trade debtors and trade creditors, on the other hand, are the amounts invoiced, which include VAT where the supply is standard rated. Dividing a VAT inclusive debtor balance by VAT exclusive sales overstates debtor days by a fifth when everything is standard rated at 20%, which GOV.UK lists as the standard rate. Divide balances by 1.2 for standard rated customers and suppliers, and leave zero rated and exempt balances as they are.

365 or 360 days

ACCA’s article mentions that exam questions sometimes assume a 360 day year. Either works if applied consistently. For monthly monitoring, many businesses measure on the last three months of sales, which reacts faster to change than an annual figure.

What does a worked example look like?

Illustration only. A small manufacturer, VAT registered and selling only standard rated goods to trade customers on credit, has annual sales of £730,000 net of VAT, cost of sales of £438,000 and credit purchases of £365,000. Average stock is £72,000, average trade debtors are £96,000 including VAT and average trade creditors are £36,000 including VAT.

Measure Calculation Days
Stock days £72,000 ÷ £438,000 × 365 60
Debtor days (£96,000 ÷ 1.2) ÷ £730,000 × 365 40
Creditor days (£36,000 ÷ 1.2) ÷ £365,000 × 365 30
Cash conversion cycle 60 + 40 less 30 70

Without taking VAT out, debtor days would show as 48 and creditor days as 36. Each day is worth a different amount: one day of sales is £2,000, one day of cost of sales is £1,200 and one day of purchases is £1,000. Cutting debtor days from 40 to 30 would therefore release about £20,000, while cutting stock by ten days would release about £12,000. Knowing what a day is worth on each line shows where effort pays most.

How is the cycle different for manufacturers and project businesses?

ACCA points out that in manufacturing, inventory days has three parts: raw materials days, work in progress days (the length of the production process) and finished goods days. Splitting stock this way shows whether cash is stuck in materials bought too early, in a slow production process, or in finished goods waiting for orders, each of which has a different fix.

The nature of the business sets limits. ACCA gives the example of a supermarket with low stock days, receivables collected within a day or two from card companies and significant payables days, giving a cycle that can be negative because cash comes in before suppliers are paid. A construction company, by contrast, may have a very long cycle because of high work in progress. For contractors and professional firms, unbilled work is the stock figure, and billing promptly at each stage is often the single biggest lever. How unbilled work is valued is covered in stock valuation.

Can you work it out from a company’s filed accounts?

Often not. Under section 444 of the Companies Act 2006, the directors of a company subject to the small companies regime must deliver a balance sheet to the registrar but may choose whether to deliver the profit and loss account. Without turnover and cost of sales, the days cannot be calculated. Section 444(2A) also allows abridged accounts where all members consent. legislation.gov.uk shows that the Economic Crime and Corporate Transparency Act 2023 substitutes a new section 444, but only so far as it confers a power to make regulations; the rest is prospective.

What a filed balance sheet does show is the trend in stock, debtors and creditors from one year to the next. A customer whose trade creditors are rising much faster than its other figures may be stretching its suppliers, which is worth knowing before extending credit to it.

What shortens the cycle?

There are three levers, and they are not equally safe.

  1. Stock. Cut slow lines, order to actual usage and lead times, and clear obsolete items. ACCA notes that modern manufacturers may use just in time techniques to reduce buffer inventory.
  2. Debtors. Agree terms before work starts, invoice on the day of delivery or completion, and chase from the due date; see credit control and aged debtors. ACCA’s article on receivables collection explains that a factor should be able to collect cash from customers more quickly than a company running its own sales ledger, and may lend against outstanding invoices, either with recourse (no protection against bad debts) or without recourse at a higher fee.
  3. Creditors. Paying on the agreed date rather than early lengthens creditor days without harming relationships. ACCA warns, however, that trying to delay payments can lead a supplier to demand cash on delivery, which cuts payables days to zero.

ACCA also notes that industry norms constrain what is achievable: if competitors offer long credit, shortening customer terms may lose business. A shorter cycle reduces the cash needed as the business grows, which should feed straight into the cash flow forecast.

How should you interpret the result?

ACCA’s article says meaningful evaluation needs the trend over time and external benchmarks such as sector averages, but warns that working capital may be poorly managed across a whole sector, so the sector leader is a better long term target than the average. A single year’s cycle on its own says little. A cycle that lengthens while sales grow is the pattern to watch, because each extra day then ties up more cash than before.

What mistakes come up most often?

  • Dividing VAT inclusive debtors and creditors by VAT exclusive sales and costs.
  • Comparing stock with turnover instead of cost of sales, which understates stock days.
  • Including cash sales in the debtor days denominator, which flatters the result for retailers and cafés with a few trade accounts.
  • Relying on year end balances in a seasonal business.
  • Treating a longer creditor period as free money, when it may cost settlement discounts or supplier goodwill.
  • Calculating the cycle once a year rather than tracking it alongside other KPIs each month.

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Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.