Rates & sources
UK company rates (Corporation Tax, VAT, payroll NI) as published by HMRC and Companies House.
Source: HMRC — Running a business — figures refreshed at the start of each tax year.
When to use this calculator
- Before pricing a job, setting margin targets, or reviewing hiring costs.
- When you want to test sensitivity around volume, VAT, markup, or overhead changes.
- When you need a practical estimate before committing to a budget or proposal.
- When you are modelling break-even volume and want to see how it shifts as overheads or prices change.
- When you are preparing a quote and need to verify that the margin holds after materials, labour, and VAT are accounted for.
A realistic Australia planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Fixed Costs (A$)
A$500
Selling Price per Unit (A$)
A$0.30
Variable Cost per Unit (A$)
A$500
After entering these figures, review break-even units, revenue needed and contribution margin together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Break-Even Units
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Revenue Needed
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Contribution Margin
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
The break-even point in units is calculated as: Fixed Costs ÷ (Selling Price per Unit − Variable Cost per Unit). The denominator — selling price minus variable cost — is known as the contribution margin per unit. To find break-even in revenue terms rather than units, divide total fixed costs by the contribution margin ratio (contribution margin per unit divided by selling price).
Enter all figures excluding VAT if your business is VAT-registered, as VAT is not part of your underlying economics. This calculator assumes a single product or a consistent product mix and does not account for step-fixed costs (where fixed costs jump at certain output levels). It is intended as a planning aid; for statutory financial reporting, use formal management accounts prepared with your accountant's guidance.
Common mistakes
- !Using optimistic assumptions without testing a more cautious scenario as well.
- !Comparing outputs from different tools without checking that the inputs match.
- !Treating the result as a final quote instead of a planning estimate.
- !Forgetting to include employer National Insurance contributions when modelling the true cost of a new hire.
- !Using revenue figures in place of gross profit when calculating margin percentage, which produces a misleadingly high result.
What to do next
- Try at least one more scenario with a lower price or higher cost so you can see the margin floor.
- Use the related calculators below to cross-check VAT, payroll, or break-even figures from another angle.
- Open one of the linked guides if you need more context before you finalise a quote or budget.
- If the margin is tighter than expected, identify which single input has the biggest impact and focus any negotiation there first.
- Keep a record of the assumptions behind this estimate so you can revisit and update it when costs or volumes change.
Frequently asked
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End-of-article next steps
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