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Compound Interest Calculator

Project future value or find the required rate to reach a target.

Result
Total Future Value

$140,297.51

Total invested

$73,000.00

Total interest

$67,297.51

Methodology & Guide

This compound interest calculator assists in two core planning tasks: estimating portfolio growth or finding the exact yield needed to reach a specific financial goal.

1. The Power of Compounding

Exponential growth happens because the interest in each period is earned not just on the principal, but also on the accumulated interest from past periods. It's the "snowball" effect.

2. Future Value Mode

The classic formulation. Input your starting balance, how much you can contribute monthly, a conservative rate estimate, and your time horizon. The tool projects your final portfolio value.

3. Required Rate Mode

If you have a defined target (e.g., $1M for retirement), this feature reverse-engineers the exact portfolio return you must achieve in the market to make the math work with your current contributions.

Benchmarks

  • Real vs Nominal Rates: For multi-decade plans, use real rates (yield minus inflation). A realistic target for a diversified stock portfolio is roughly 3% to 5% annualized real return.
  • Time is the Greatest Lever: Due to exponential mechanics, delaying investments by just a few years demands drastic increases in savings rate or yield to compensate.

Common Pitfalls

  • Yield Chasing Fantasy: Projecting consistent high double-digit returns. No safe long-term asset yields such rates continuously without outsized risk.
  • Ignoring the Base Contribution: Attempting to find miracle assets to boost yield, rather than focusing on increasing your baseline monthly savings capacity.

Mathematics

Future Value with Contributions

FV = PV(1 + r)n + PMT ·
(1 + r)n - 1r

Rate Conversion

ra = (1 + rm)12 - 1

Variable Legend

  • FV = Future Value
  • PV = Initial Value (Principal)
  • PMT = Monthly Contribution
  • r = Monthly Rate
  • n = Number of Months

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Retirement Projection

Plan when your portfolio can sustain spending in real terms.

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CDB vs LCA/LCI Comparison

Compare tax-exempt (LCA/LCI) with taxed fixed income (CDB).

SILVER

Import Price Index (Harmonized System): Silver (Including Silver Plated with Gold or Platinum), Unwrought or in Semimanufactured Forms, or in Powder Form