Compound Interest Calculator App

Prosper helps you model compound growth across decades with your contribution and return assumptions, so you can evaluate realistic long-term outcomes.

Contributions + growth

Simulate recurring contributions with expected annual growth to understand accumulation pace over time.

Tax-aware outcomes

Estimate net outcomes by configuring tax behavior on sell events and account-level tax treatments.

Inflation-aware planning

Because a million bucks in 2050 won't buy what it does today. Stress-test assumptions to keep your purchasing power real.

Scenario snapshots

Save variations of your assumptions. Compare the "safe" path with the "if everything goes perfectly" dream scenario.

Planning tips

  • Use a conservative baseline return.
  • Model one stress scenario with lower growth and higher costs.
  • Compare outcomes before locking down recurring contributions.