Monthly Compound Interest Calculator — See Your Growth
Monthly contributions are the most powerful way to build wealth. Calculate exactly how much your monthly savings will grow with compound interest.
Compound Interest
How It Works
Monthly contributions combined with compounding create a snowball effect. $500/month at 7% for 20 years turns $126k of your money into ~$260k total.
Every $100/month at 7% grows to ~$52k over 20 years. Bump to $500/month and you hit ~$260k. At $1,000/month you reach ~$520k.
Dollar-cost averaging (investing a fixed amount monthly) smooths out market volatility and removes emotion from investing.
Automate your contributions — 'pay yourself first' by investing the day after each paycheck. You can't spend what you can't see.
Frequently Asked Questions
How much will $500/month be worth in 20 years?
At 7% annual returns, roughly $260,000. You'll have contributed $120,000 and earned ~$140,000 in compound growth.
What's the best monthly contribution amount?
Whatever you can sustain for 20+ years. $500/month is a sweet spot — aggressive enough to build real wealth but manageable on a median salary.
Does compounding work better with monthly or yearly contributions?
Monthly, because your money starts working earlier. $12k/year contributed monthly beats annual lump-sum contributions by ~0.5% annually on average.