What Monthly Contribution Reaches Your Target
Results
Visualization
How It Works
We solve the future-value of an annuity for the payment. With monthly rate r and n months, the balance from contributions is P x ((1+r)^n - 1) / r plus growth on any starting amount. Rearranging for the payment gives P = (Target - Starting x (1+r)^n) x r / ((1+r)^n - 1). The monthly rate comes from the annual rate via (1+annual)^(1/12) - 1. The chart shows your contributed principal against the total balance that compounding builds.
What Should You Do?
Automate the contribution so it leaves on payday without a decision. Treat the return as an assumption, not a promise; using 5-6% builds in safety margin against a shortfall. If the required amount feels high, extend the horizon or raise the starting balance rather than assuming an unrealistic return. Re-run yearly as income and goals change, and keep the return assumption conservative for important goals.
Frequently Asked Questions
Is 7% a safe assumption?
A diversified stock index has averaged near 7% long term after inflation, but results vary. Use 5-6% for a conservative plan.
Does this include taxes or fees?
No. Real returns are reduced by expenses and taxes, so the actual amount needed is usually higher.
What if I get a raise later?
Re-run with a larger monthly amount to see how much sooner you reach the goal.
Can the payment be negative?
If your starting amount already exceeds the goal, the tool shows zero required contribution.
How accurate is the math?
Exact for the assumptions entered; accuracy depends entirely on whether those assumptions hold.