Investment Profit Calculator
✓ Verified formulaTrack monthly profit on an investment, add new months, and increase capital by any amount when you invest more. Everything stays in your browser. New here? Tap Load example to see how it works.
Monthly profit
Just enter each month's profit. Added more capital later? Use the + capital button on that month.
How the returns are calculated
Each month's return is that month's profit divided by the capital invested that month, shown as a percentage. The summary shows total profit, average monthly profit, average monthly return percent, return against current capital, and an annualized figure (average monthly percent × 12). When you add fresh capital mid-way, later percentages are measured against the larger base — so a fixed profit reads as a smaller percentage once your capital grows, which is the honest way to track a scaling investment.
Private and editable
Add a row for each new month, edit any profit or capital figure directly, and remove months you don't want. Nothing is uploaded — the calculator runs entirely on your device, so your investment figures stay private.
Formula used
Annualized = average monthly return % × 12 (simple, not compounded).
How to use this tool
- 1Enter your starting capital at the top.
- 2Add each month's profit in the rows.
- 3Use + capital on any month you invested more.
- 4Read the totals, average return and chart.
Frequently asked questions
How is monthly return calculated?
Each month's return is that month's profit divided by the capital invested that month, shown as a percentage.
What does annualized mean here?
It's the average monthly return percent multiplied by 12 — a simple yearly projection, not compounded.
Can I add capital by a custom amount?
Yes — set any top-up amount, then tap '+ Add capital' on a month to increase its capital by that amount.
Is my data uploaded?
No — the calculator runs entirely in your browser and nothing is sent anywhere.