How Much to Invest Monthly to Reach Your Goal
Results
Visualization
How It Works
The calculator solves the future-value of an annuity formula for the payment. With a monthly rate r and n total months, the future value of contributions is FV = P × ((1+r)^n − 1) / r plus the growth on any starting balance. We rearrange to find P = (Target − Starting×(1+r)^n) × r / ((1+r)^n − 1). Returns are compounded monthly from your annual rate using (1+annual)^(1/12) − 1. The chart shows your contributed principal (green) versus the total balance (blue) growing from compounding.
What Should You Do?
Set the monthly amount on autopilot with an automatic transfer so you never skip a month — consistency matters more than timing. If the required number feels high, either extend the timeline, raise your expected return assumption cautiously, or increase your starting balance. Treat the return input as an assumption, not a promise; using a conservative 5-6% figure builds in a safety margin. Re-run the calculator yearly as your income and goals change.
Frequently Asked Questions
Is 7% a realistic return assumption?
A broad stock index has historically averaged roughly 7% after inflation over long periods, but year-to-year results vary widely. Use 5-6% for a conservative plan.
Does this include taxes and fees?
No. Real-world returns are reduced by expense ratios, taxes, and inflation. The inflation calculator on this site shows the after-inflation effect.
What if I get a raise later?
You can model higher contributions by re-running with a larger monthly amount, or use the fee and inflation simulators to see long-term effects.
Should I invest monthly or lump sum?
Historically monthly investing (dollar-cost averaging) slightly trails a lump sum in rising markets but reduces timing risk. See our monthly vs annual comparison tool.
How accurate is the result?
The math is exact for the assumptions you enter. Accuracy depends entirely on whether your return and timeline assumptions hold.
Can I use this for a college fund?
Yes. Set the target to the projected cost and years to the child's age. For tax-advantaged options see our 529 comparisons on related sites.