ROI Calculator
ROI Calculator compares gain or loss with the original investment: final value minus investment, divided by investment. It produces a simple percentage for one beginning and one ending value. The result does not annualize time or include interim cash flows, taxes, inflation, financing, opportunity cost, risk, or whether the final value is realized.
Runs locally — files stay on your deviceHow is ROI calculated?
Subtract the investment from final value, divide by the investment, and multiply by 100.
Formula: ROI = (final value − investment) ÷ investment × 100
ROI expresses gain or loss relative to the starting investment
A positive ROI means final value exceeds the entered investment; a negative ROI means it is lower. A 50% ROI over one month and over ten years share the same simple percentage but are not economically equivalent.
How it works
Enter comparable beginning and ending values that include the costs you intend to measure. State the time period and cash-flow assumptions outside the result when presenting it.
Key concepts
Cost basis must be complete
Leaving out setup, financing, transaction, or operating costs can overstate ROI.
ROI has no time dimension
The formula does not distinguish how long the capital was committed.
When to use it
- Check a simple one-period investment return.
- Compare scenarios with the same time and cost basis.
- Express a monetary gain relative to initial outlay.
When not to use it
- Do not compare different time spans without annualization.
- Do not omit material fees, taxes, maintenance, or additional contributions.
- Do not use simple ROI for irregular cash flows requiring IRR or NPV.
Worked examples
Positive return
- Input
Investment 1,000; final value 1,200- Expected output
20% ROI
The 200 gain is twenty percent of the original 1,000.
Loss
- Input
Investment 500; final value 425- Expected output
−15% ROI
The ending value is seventy-five below the starting amount.
Same ROI, different time
- Input
1,000 becomes 1,100 in one year or five years- Expected output
10% simple ROI in both cases
Time requires a separate annualized measure.
Common mistakes
Dividing by final value
ROI convention uses the initial investment as denominator. Correction: Divide gain by initial investment.
Ignoring added costs
The gain and cost basis become inconsistent. Correction: Include all costs relevant to the decision.
Comparing unequal periods
Simple ROI does not account for time. Correction: Use CAGR or another time-aware method where appropriate.
Best practices
- Define cost basis and final value consistently.
- Report the measurement period alongside ROI.
- Use cash-flow-aware metrics for complex projects.
Related operations and differences
Break-Even Price Calculator
Choose Break-Even Price Calculator when you need to find the unit price that covers cost and fees.; use ROI Calculator specifically for roi.
Simple Interest Calculator
Choose Simple Interest Calculator when you need to calculate non-compounding interest.; use ROI Calculator specifically for roi.
CAGR Calculator
Choose CAGR Calculator when you need to calculate compound annual growth rate.; use ROI Calculator specifically for roi.
Discount Calculator
Choose Discount Calculator when you need to calculate final price and savings.; use ROI Calculator specifically for roi.
Tip & Split Bill Calculator
Choose Tip & Split Bill Calculator when you need to calculate tip, total and amount per person.; use ROI Calculator specifically for roi.
Unit Price Calculator
Choose Unit Price Calculator when you need to compare cost by calculating price per unit.; use ROI Calculator specifically for roi.
Limitations and privacy
- This calculator provides a mathematical estimate, not financial, tax, legal, or investment advice.
- No time adjustment, cash flows, risk, inflation, financing, fees, or taxes are modeled.
- An initial investment of zero has no defined ROI.
Financial inputs are calculated locally in this browser and are not uploaded.
Frequently asked questions
What is the ROI formula?
(Final value − investment) ÷ investment × 100.
Is ROI annualized?
No. It contains no time term.
Can ROI be negative?
Yes, when final value is below the investment.
When should I use CAGR instead?
Use CAGR when comparing start and end values across a multi-year period as a smoothed annual rate.