1. Set the base
Enter the starting amount, monthly contribution, term, and annual rate. The curve already shows monthly compounding.
FINANCE LAB · INTERACTIVE PROJECTION
Compound interest
Edit the plan right on the curve. Every change recalculates contributions, interest, scales, and the final projection in real time.
Portfolio projection
Drag the circle to move the start and amount. Drag the square to change duration.
Click the chart to create a future change. Click a marker to edit that change.
FINANCE LAB
Changes
MINI TUTORIAL · FINANCE LAB
Build a projection that follows real decisions
2. Create plan changes
Add a point for a raise, a pause, an extra contribution, or a withdrawal. Every segment has its own start, end, and amount.
3. Edit in the chart
Drag the circle to change month and contribution. The final square extends or shortens the period. Everything responds in the same gesture.
4. Read the impact
Select an event to view portfolio value at that period, accumulated interest, and how that choice changes the final total.
Complete guide: projections are not return promises
The calculator applies monthly compounding from the annual rate you enter. It is a scenario tool: returns, inflation, and contributions can change in real life. The green line is projected value; the pale line is cash contributed. The distance between them is accumulated return. Events temporarily replace the base contribution and only change months after their start — no edit rewrites the past.
Recurring withdrawals enter the projection at the selected interval and frequency. They reduce both the balance and future interest; with protection on, the projection stops at zero when funds run out.
Frequently asked questions
Does dragging a point change the result?⌄
Yes. Moving sideways changes when the contribution starts; moving up or down changes the monthly amount. The future is recalculated immediately from that point.
How do I set how long a contribution lasts?⌄
Drag the square handle at the end of the segment or edit the Ends field. The base contribution resumes after that month unless another event replaces it.
Does the real value include inflation?⌄
When you enter inflation, the Value in today's money card discounts it from the final projection. It is a reference, not a purchasing-power guarantee.
Can I undo a drag?⌄
Yes. Use Undo, Redo, or Ctrl/Cmd + Z and Ctrl/Cmd + Shift + Z.
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