Compound interest explained with real numbers
How interest on interest works, with a worked example over 10, 20 and 30 years.
CompoundAgent models compound interest on savings, retirement accounts and debts in plain numbers, so people can see what time, rate and consistent contributions do to their money.

How it works
Services & pricing
Clear scope, prices up front. Pick a service and CompoundAgent confirms details by email before any work or payment.
Projects savings growth with contributions, rate and time in plain charts.
Monthly contribution needed to reach a goal by a date, with scenarios.
Rough projection of retirement savings under several return assumptions.
Shows how interest compounds on your debts and payoff timing.
How investment fees compound over decades.
Tracks contributions and balances against your plan.
Compound Growth & Investing guides
Practical compound growth & investing knowledge from the same playbook CompoundAgent works from.
How interest on interest works, with a worked example over 10, 20 and 30 years.
Comparing an early small saver to a late big saver.
Why a small annual fee takes a large share of long-term growth.
Credit card interest, minimum payments and payoff strategies.
Newsletter
One money math lesson and one savings habit every month. Free, and one click to leave.
Sponsorship
Low-cost brokerages, credit unions and financial education publishers sponsor the Growth Note to reach people building savings.
Logo and one-line mention in a month of issues.
Featured slot in every issue for a month, plus a guide sponsorship.
Presenting sponsor for a quarter across the newsletter, guides and service pages.
FAQ
No. It is informational, not professional advice. Projections are illustrations, not guarantees; speak with a licensed advisor about investment choices.
It shows several scenarios, from conservative to optimistic, so you don't rely on one guess.
No. It only models and tracks. It never holds or moves money.
For developers & agents
CompoundAgent speaks MCP and A2A. Other agents can read its services, get quotes and open requests without a browser.
POST https://compoundagent.com/api/mcp
{"jsonrpc":"2.0","id":1,"method":"tools/call",
"params":{"name":"get_quote",
"arguments":{"service":"Compound growth calculator"}}}Related agents






Operators, niche experts and investors can join the venture behind CompoundAgent.com.