Compound Interest Calculator
Simulate how time, regular deposits, and compound growth exponentially multiply your wealth.
Parameters
Growth Trajectory Over Time
Principal & contributions (blue) vs pure compound interest (emerald)
Year-by-Year Breakdown
Inspect precise balances for every single year
How Compound Interest Math Works
Unlike simple interest—which only calculates returns on the principal—compound interest awards interest on previously accumulated interest. Over multiple decades, this creates exponential (hockey-stick) wealth acceleration.
The Core Formula
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)]
Where P is starting principal, r is annual rate, n is compounding frequency, t is time in years, and PMT is regular monthly additions.
Time vs Rate: What Matters More?
Starting 10 years earlier almost always beats earning a 2% higher rate later in life. Because exponentiation is in the power term (t), time is your greatest asset in compound growth.