About GrowthLab
GrowthLab is an independent personal-finance publisher. We build free, fast calculators for the questions people actually ask about long-term money — and we pair each one with a long-form article that explains the underlying math, the assumptions, and the limits.
Why we exist
The internet has thousands of compound-interest calculators. Most are tucked behind brokerage landing pages, ask for an email address, or quietly inflate their default rate to make a product look more attractive. The articles around them tend to be SEO-optimized fluff written to rank, not to teach.
We built GrowthLab because the math is genuinely useful and the existing tooling is genuinely annoying. Our calculators are free, require no signup, work on mobile, and use conservative default assumptions. Our articles cite primary sources — the Federal Reserve, BLS, SEC, and peer-reviewed research — instead of recycling each other.
What you'll find here
Calculators for compound interest, doubling and tripling time (Rule of 72 / Rule of 114), daily investing, $1,000 long-horizon growth, and a millionaire goal-setting tool. Inputs are tunable; results are inflation-adjustable; every formula is documented on the page.
A long-form blog that goes deeper: how compound interest actually works, what 30 years of S&P 500 returns look like next to bonds and savings, when the Rule of 72 breaks, how to size your real retirement number, and what the research actually says about dollar-cost averaging.
Our principles
- Free, with no email wall. Nothing on this site requires a signup to use.
- Conservative defaults. Our calculators default to assumptions that under-promise rather than over-promise. Optimism is the most common way personal-finance tools mislead.
- Primary sources only. If we cite a number, you can click through to the government dataset, regulatory filing, or peer-reviewed paper it came from.
- No personalized advice. We're a publisher, not a financial advisor. We don't know your situation, and we don't pretend to.
- Independent. Supported by display advertising only. No affiliate links, no sponsored content, no pay-to-play rankings.
Who's behind it
See our author page for the team and our editorial standards for our sourcing, review, and corrections process. Our financial disclaimer covers what our content is and is not intended to do.
Get in touch
Corrections, source disputes, feedback, or article suggestions are genuinely welcome. Email contact@fundgrowthx.com or use our contact page.