How Much Working Capital Does My Business Need?

Your working capital requirement is the funding your business needs to cover the gap between paying for stock, staff and suppliers and getting paid by customers, plus a buffer for delays. You can estimate it in four steps: measure your working capital cycle, cost it, add a buffer for your real risks, and adjust for growth. A cash flow forecast then helps you identify how much additional funding, if any, you need.

‍

Working capital ratios give you a snapshot of your business, but they do not directly answer the practical question: “How much money do I need available so the business runs without me worrying about payroll?” The answer depends on how long your money stays tied up in each trading cycle, when payments come in and bills fall due, and how much buffer your business needs to handle delays or unexpected costs. You can estimate this using your accounts and a cash flow forecast.

What is working capital?

Working capital supports a business’s day-to-day operations: buying stock, paying staff and suppliers, and covering the period between doing the work and being paid for it. It is calculated as current assets minus current liabilities. If you hold £180,000 in stock, debtors and cash, and owe £120,000 in supplier invoices, VAT and other short-term liabilities, your working capital is £60,000.

That figure is a snapshot of your position today. It does not mean you have £60,000 available to spend: some of it is tied up in stock and unpaid invoices. To work out how much cash you need available to trade smoothly, including the weeks when outgoings run ahead of income, you need to understand your working capital cycle and map the payment timings in a cash flow forecast.

Why "enough" is different for every business

Two businesses with identical revenue can have wildly different working capital needs, and timing is a major reason.

A consultancy invoices monthly, holds no stock, and pays salaries as its main cost. It may need to cover work done before each invoice is issued, plus the time customers take to pay. A retailer importing seasonal stock might pay suppliers 3 months before the goods sell, including shipping and storage time, and then wait for payment settlement. Same turnover, entirely different requirement.

This is why generic rules of thumb, such as holding 10% of turnover, can miss the mark. A more useful estimate comes from your own trading cycle, costs and payment timings. The following 4 steps show how.

How to calculate your working capital requirement

Step 1: Work out how long your money is tied up

This is your working capital cycle, also called the cash conversion cycle, measured in days. It has 3 components:

• Stock days: the average time you hold stock before selling it. If you hold no stock, this is 0.
• Debtor days: the average time between invoicing a customer and receiving the money.
• Creditor days: the average time you take to pay supplier invoices. Agreed supplier credit reduces the time you need to fund the gap yourself.

The cycle is stock days plus debtor days minus creditor days. A wholesaler holding stock for 45 days, collecting invoices in 40, and paying suppliers in 30 has a working capital cycle of 55 days. This means an average gap of 55 days between paying suppliers and receiving the money from customers.

Our guide to understanding your working capital cycle works through this measurement in more detail.

Your accountant can help you check the figures against your own accounts.

Step 2: Cost the cycle

Now attach money to those days. Estimate stock at cost, unpaid customer invoices, and unpaid supplier invoices using the relevant daily figures. For illustration, assume the wholesaler above has daily cost of sales and credit purchases of £3,000, and daily credit sales of £4,000.

Multiply each daily figure by the relevant period: stock is £3,000 × 45 days = £135,000; debtors are £4,000 × 40 days = £160,000; and creditors are £3,000 × 30 days = £90,000. Stock plus debtors minus creditors gives £205,000 tied up in trading, before allowing for a cash buffer or growth. This is not necessarily the amount you need to borrow: your cash flow forecast will show any additional funding needed.

Step 3: Add a buffer for your actual risks

The core figure reflects average trading balances. Actual payment dates and spending can vary, so the buffer matters, and it should reflect your specific exposures rather than a generic percentage:

• Payment behaviour. If your largest customer pays late by 2 weeks once a quarter, price that in: move the expected receipt back by 14 days in your forecast and check the resulting cash gap. Avoid counting delays already included in your baseline twice.
• Seasonality. If your quiet quarter runs 30% below average while fixed costs continue, check how much cash the business needs across the quiet months, allowing for any costs that fall with sales.
• Lumpy obligations. VAT quarters and tax instalments are predictable but large. Include them in your baseline forecast, particularly where a tax date falls in the same fortnight as payroll or a stock order, rather than adding them again as a buffer.

Step 4: Adjust for growth

Growth can increase the requirement before the extra cash comes in. Extra monthly sales can mean more stock bought earlier, sometimes more staff, and a larger pool of unpaid invoices, all needing funding through the working capital cycle. To estimate the increase, calculate the extra stock and debtors, then subtract the extra supplier credit using the same method as above. Add any extra payroll and other cash commitments to your forecast. A business planning to grow sales by £20,000 a month will need different amounts of additional working capital depending on its costs and payment timings.

Sense-check the number against your forecast

The 4 steps help you estimate what is tied up in trading and where cash pressure may arise, but averages behave better than real calendars do. The cross-check is a 13-week cash flow forecast: start with your available cash, map your expected inflows and outflows week by week, and look at the deepest dip in the closing-balance row before adding new funding. If the balance falls below the minimum cash buffer you want to maintain, the difference is your additional funding gap. This is different from the total amount tied up in working capital: some of that investment is already funded. Check daily balances in tight weeks too, because a positive weekly closing balance can hide a shortfall earlier in the week. Our guide to calculating your cash flow gap shows the same week-by-week method applied to sizing an individual gap.

Signs you are running below your requirement

You do not need to wait for the arithmetic to tell you. A business running under its working capital requirement often shows it: supplier payments drift past their terms, quarterly tax bills require special arrangements rather than routine payment, discounts for early settlement get declined because the money is not there to take them, and decisions start being made on what the account can bear this week rather than what the business needs. If several of those feel familiar, it is worth running the 4 steps above and checking your forecast to measure the gap between what you have available and what you need.

Where funding fits

Once you know your requirement, the shape of any shortfall helps you decide what kind of funding fits it.

A one-off step change, such as a big contract or a planned expansion, can suit a fixed loan sized to the specific need. A gap that opens and closes with your trading cycle can suit a revolving facility, because the need itself revolves: you draw as stock is bought or invoices await payment, and repay as the money comes back in, in line with the agreed repayment terms. Juice Flex is a continuous line of credit that works alongside your business.

Revisit the number as the business changes

A working capital requirement is not a constant. It changes when your supplier terms change, when a big customer renegotiates payment terms, when you add a product line that holds stock differently, and as the business grows. Treating the calculation as a quarterly habit rather than a one-off exercise helps you stay prepared

‍

This guide provides general information, not financial advice. Any calculations are illustrative. Check your own figures, assumptions and funding needs with your accountant before making decisions, and do not rely on this guide alone.

Juice lends to UK limited companies, subject to status.

‍

‍