ROI Calculator — Methodology

Step-by-step calculation

Measure ROI on any business spend — marketing, equipment, training — with optional annualisation for fair comparisons.

1. 1

   Enter initial investment

   The total amount you spent upfront on the investment.

2. 2

   Enter net return

   The total return or revenue the investment generated.

3. 3

   Optionally enter the period in months

   Add the investment period to see annualised ROI alongside total ROI.

4. 4

   Read ROI, net profit, and annualised rate

   The calculator shows ROI as a percentage, net profit in cash, and the annualised rate for comparison against other investments.

Assumptions and overrides

Simple ROI does not account for the time value of money. For investments held over multiple years, use the annualised ROI for fair comparison.

Every region default on the calculator is editable. If your effective rate, fee, or threshold differs from the headline figure shown, type your own number into the field — the calculator recomputes instantly without leaving this page.

Review cadence and corrections

This methodology and the underlying rate defaults are reviewed at least annually, and immediately following any change to the headline rate from IRS, HMRC, or SARS. Every substantive update is recorded on the public changelog. Spotted an error? See the corrections policy for how to report it.

See the full editorial policy for the standards every page on BusCalcTools is held to.