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ROI Calculator

Calculate return on investment as a percentage of your initial outlay. Enter net profit and investment cost to measure efficiency of any business decision.

Last reviewed 15 August 2026

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When to use this calculator

  • Before choosing between saving, investing or changing a contribution.
  • When you want to compare cautious, base and optimistic return assumptions.
  • When you need a projection before making a longer-term decision.
  • When you want to see whether starting earlier or contributing more changes the outcome more.

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
Profit (£)20000
Total Investment (£)£15,000

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

How to read your results

Return on Investment

A projected outcome under the growth rate you entered. Real-world returns fluctuate, so also check a more conservative assumption.

Method & assumptionsAuthoritative sources

This calculator divides net profit by total investment and expresses the result as a percentage. It is a simple, universal performance measure that works across all property strategies: buy-to-let, flipping, development, and commercial property. The key to an accurate result is using comprehensive figures for both inputs.

For profit, start with sale proceeds or current market value, then deduct purchase price, all transaction costs (property transfer tax, legal fees, surveys), any renovation or improvement spend, ongoing costs during the holding period, and selling costs including estate agent fees. For investment, use the total cash outlay — deposit, fees, and capital improvements — rather than the gross property price if you used mortgage finance. Note that this calculator does not model Capital Gains Tax, which is chargeable on disposal of investment property at 18% (basic rate) or 24% (higher rate) after your annual CGT allowance. Always seek professional tax advice before completing a property transaction.

Common mistakes

  • !Assuming a constant return without checking a more conservative growth rate.
  • !Forgetting ongoing contributions, fees or tax wrappers where relevant.
  • !Focusing only on the final balance instead of the path required to reach it.
  • !Ignoring the drag of charges over a long period.

What to do next

  • Test a cautious, expected and optimistic growth rate.
  • Compare this result with related savings or retirement tools before committing more money.
  • Consider charges and any tax wrapper that applies.
  • If the projected balance falls short, increase the contribution until the result meets your goal.

Frequently asked

The investment calculator multiplies your initial investment by the annual return rate, compounded over the number of years specified. It assumes regular contributions (if specified) are added at intervals and also earn returns.

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