Investment Projector

Open tool

Project a SIP and lump-sum investment month by month, with editable per-month contributions, returns, and an actual-vs-projected net worth chart.

Project how an investment can grow month by month from a starting amount and a monthly SIP (systematic investment plan — a fixed amount invested every month), then adjust any single month or every month from a point onward: change the contribution, change the return, add a lump sum. Enter your real net worth as you go and compare it with the plan on a chart.

How it works

Each month starts from the previous month's closing balance. The month's contribution is the SIP plus any additional investment, and it is added at the start of the month. Returns for the month = (Opening balance + Contributions) × Annual rate ÷ 100 ÷ 12. Closing balance = Opening + Contributions + Returns.

So the annual return is applied as a simple rate split evenly across twelve months (10% a year becomes about 0.83% a month, which compounds to roughly 10.5% over a full year). Actual net worth values you enter are drawn on the chart for comparison only; they never change the projection.

Amounts are labelled with the site-wide currency chosen in Settings; nothing is converted. Months are labelled with real calendar names from the start month and year you choose (the labels do not affect any maths).

How to use it

Fill in the Starting amount, Expected annual return, Monthly SIP and Investment horizon, and choose the Start month and Start year.
Read the summary figures and the chart.
Open the Month-by-month schedule. Click any SIP, Additional, or Rate value to change it for one month or from that month onward.
As real months pass, click the Actual net worth cell for that month, type your real figure, and save it to see how you are tracking against the plan.
Click Download to save your plan as a file, and Load it back another day — nothing is stored in the browser between visits.

Options & controls

Starting inputs

Starting amount: What you have invested at the start, in the current currency. Must be 0 or more. Default: 10,000.
Expected annual return (%): The yearly return you assume, in steps of 0.01. Must be 0 or more. Default: 10. Individual months can override it.
Monthly SIP: The amount you invest every month. Must be 0 or more. Default: 5,000. Individual months can override it.
Investment horizon (years): How long to project, from 1 to 50 years. It is converted to whole months. Shortening it deletes any monthly overrides and actual figures beyond the new end; they do not come back if you lengthen it again. Default: 10.
Start month / Start year: The first month of the plan. Used only for naming the months in the schedule and chart. They default to the current month and year.

File buttons

Download: Saves the inputs, every override, and every actual figure as investment-projection.json. It is your only way of keeping a plan.
Load: Opens a file picker for a file previously saved with Download and replaces everything on the page with it. A file from anywhere else is rejected with “This file isn't a valid Investment Projector export.”, and an unreadable file with “Couldn't read that file.”
Reset: In the title row. Restores the default inputs and removes every override and actual figure. It does not ask for confirmation.

Schedule controls

Year groups: The schedule is split into 12-month blocks counted from your start month. Each block's heading gives its date range, the amount invested in it, and where the balance ends. Only the first block is open at first; click a heading to open or close it.
Expand all / Collapse all: The two icon buttons above the schedule open or close every block at once.

Editing a cell (SIP, Additional, Rate, Actual net worth)

Click a value to turn it into a small number box (0 or more, decimals allowed).

This month: SIP, Additional and Rate cells. Applies the new value to that one month only. Pressing Enter does the same.
Onward: SIP, Additional and Rate cells. Applies the value to that month and every month after it, until another change takes over. It replaces any other “Onward” changes you had set for later months; single-month changes for later months stay.
Save: Actual net worth cells. Records your real figure for that month.
Escape or clicking away: Cancels the edit without changing anything.
Amber bar and ×: A cell that differs from the plan has an amber mark on its left edge and a small × beside it. Click × to remove the change that starts at that month. To remove an “Onward” change, click × on the month where it started.

What each editable column means

SIP: The regular monthly investment for that month. Change it to model a raise, a pause (0), or a step-up.
Additional: An extra amount on top of the SIP — a bonus or lump sum for one month, or a higher recurring contribution if you use Onward. The plan starts at 0.
Rate: The annual return percentage applied in that month. Use it to test a bad or good year (for example, 4% for a few months). Shown as a percentage.
Actual net worth: Your real total at the end of that month. Empty cells show “Add”.

Reading the results

Summary

Final projected corpus: The closing balance in the last month.
Total invested: The starting amount plus every SIP and additional investment.
Total returns: Final projected corpus minus total invested.
Latest actual net worth (month): Appears only once you have entered an actual figure: the most recent one, with its month.
Copy: Copies these figures as one line of text.

Chart

Projected line: The closing balance for every month of the plan.
Actual (entered) points and line: Your actual net worth for the months you entered, joined by a line wherever the months are consecutive. Until you enter one, a hint tells you where.
Hover or touch: Move over the chart to see a tooltip with that month's Projected value and, if entered, the Actual value.

Schedule columns

Month: The calendar month.
Opening: The balance at the start of the month.
Returns: The return earned in the month, calculated on the opening balance plus that month's contributions.
Closing: The balance at the end of the month, which becomes the next month's opening.

Tips & guidelines

Change the Investment horizon first, before adding overrides or actual figures. Shortening it — even for a moment, such as while you type a new number — removes anything beyond it.
Download your plan regularly if you are using it to track real progress. Nothing here is saved automatically, and a refresh clears it.
Use a low-return scenario alongside your expected one (for instance 6% and 10%) to see a sensible range instead of a single number.
To model an annual step-up, use Onward on the month each raise takes effect: the SIP change then applies from that month forward.
Compare the actual and projected lines in the chart to decide whether to invest more, or to reset your assumptions.

Limits

It is a simplified projection: no inflation, taxes, fees or market ups and downs unless you enter a different rate for those months.
Returns are applied as a steady simple monthly rate, which is not how real markets behave.
The maximum horizon is 50 years, in whole months.
The tool does not include withdrawals as a separate feature; you can only add money (values must be 0 or more).
It does not give financial advice; treat the results as an illustration.

Saved in your browser

Nothing is saved in the browser. Everything — inputs, changes and actual figures — is lost when you refresh or close the tab unless you use Download first. The downloaded file is stored wherever you save it, on your own device.

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