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How to calculate IRR

IRR Calculator computes internal rate of return from cash flow stream (initial outflow then inflows). Runs entirely in your browser

Illustration for the how-to guide on IRR

Photo: Carlos Muza on Unsplash

What this calculator computes

TopicIRR
CategoryBusiness & SaaS
InputsMRR, ARR, churn, customer count
OutputLTV, CAC payback, runway
Math modelSaaS unit economics formulas
Best forFounders sizing SaaS or service businesses
CostFree, no login, in browser

Step by step

  1. Open IRR Calculator

    Visit /tools/irr-calculator in any modern browser. The tool loads instantly and runs entirely on your device, so no inputs are transmitted to a server.

  2. Gather your inputs

    Have your cash flow stream (initial outflow then inflows) ready. Accuracy on the output depends entirely on the quality of these numbers. If a value is uncertain, use the most realistic figure rather than rounding aggressively.

  3. Enter the values

    Fill each field in turn. IRR Calculator validates ranges as you type, so an obvious typo (for example a negative balance where one cannot exist) will flag immediately.

  4. Read the result

    The output is a internal rate of return, computed using npv root finding. Treat it as a precise answer to the question you posed, not an approximation.

  5. Verify and compare

    Re-run the calculation with a slightly different input to test sensitivity. For deeper comparison against another approach, see related tools in the Business & SaaS hub or pick a related irr tool below.

When to use IRR Calculator

  • Modelling runway under a new spend plan
  • Comparing two pricing models on the same cohort
  • Sizing payback on a customer acquisition campaign

Frequently asked questions

What does IRR Calculator compute?

IRR Calculator computes a internal rate of return from cash flow stream (initial outflow then inflows), using npv root finding.

Is IRR Calculator free?

Yes. It is free, runs in your browser, requires no login, and does not transmit your inputs to any server.

What inputs do I need to use IRR Calculator?

You need cash flow stream (initial outflow then inflows). Accuracy depends entirely on the inputs you provide.

When should I use IRR Calculator?

Use it when your task is single-rate-of-return summary and you need a quick, deterministic answer for a irr question.

Where can I find related tools?

Browse the full Business & SaaS category for tools that share the same inputs or solve adjacent problems.

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