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Cash Flow Calculator

Calculate net cash flow by totalling inflows and outflows. Track whether your business or household generates a positive or negative cash position each period.

Last reviewed 15 August 2026Source: HMRC — Running a business

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Calculator inputs

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Rates & sources

UK company rates (Corporation Tax, VAT, payroll NI) as published by HMRC and Companies House.

Source: HMRC — Running a business — check the linked guidance and any live quote before acting.

When to use this calculator

  • Before pricing a job, setting margin targets or reviewing hiring costs.
  • When you want to test sensitivity around volume, tax, markup or overheads.
  • When you need a practical estimate before committing to a budget or proposal.
  • When you are modelling break-even volume as costs or prices change.

A realistic UK planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

A realistic UK planning example
InputValue
Monthly Revenue (£)6
Cost of Goods Sold (£)£500
Operating Expenses (£)5000
Tax Rate (%)5%

After entering these figures, focus on result first and then rerun the tool with a more cautious assumption.

How to read your results

Result

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Method & assumptionsAuthoritative sources

This calculator produces a rolling cash flow forecast by taking your opening bank balance, adding projected cash receipts from sales, and deducting cash payments for costs in each period. Enter figures as cash amounts — that is, money you actually expect to receive or pay in the period, not accruals or invoices raised. VAT-registered businesses should include the VAT element in both receipts and payments and show the net VAT settlement as a separate line in the period it falls due.

The model does not incorporate capital expenditure, loan repayments, or tax liabilities unless you add them explicitly. It is a planning tool and will only be as accurate as the assumptions you feed into it. Review and update your forecast monthly against actuals to keep it useful.

Common mistakes

  • !Using optimistic assumptions without testing a more cautious scenario.
  • !Using revenue in place of gross profit when calculating margin.
  • !Treating the result as a final quote instead of a planning estimate.
  • !Forgetting employer on-costs when modelling the true cost of a hire.

What to do next

  • Try at least one more scenario so you can compare a realistic range.
  • Use the related calculators below to cross-check the decision from another angle.
  • Write down the key outputs from your best scenarios before you decide.
  • If the result surprises you, change one input at a time to isolate the driver.

Frequently asked

Cash flow is the net amount of money moving in and out of a business. Positive cash flow means more money coming in than going out. Many profitable businesses fail due to poor cash flow management.

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