See exactly how your money can grow
LanternTools gives you clear, honest financial calculators for compound interest, savings goals, investment growth, and retirement planning. No jargon, no spam.
Seven calculators for every money decision
Whether you're saving for a house, planning retirement, or deciding whether to pay off debt first — there's a calculator here for you.
Compound Interest Calculator
See how your money grows with compound interest over time.
Savings Goal Calculator
Find out exactly when you'll reach your savings target.
Investment Growth Calculator
Project how your investment portfolio could grow over years.
Regular Contribution Calculator
See the impact of consistent, regular deposits on your wealth.
Retirement Growth Calculator
Estimate your retirement savings balance at any retirement age.
Inflation-Adjusted Returns Calculator
Understand the real value of your returns after inflation.
Debt Payoff vs Investing Calculator
Compare paying off debt aggressively vs investing surplus cash.
Calculators built for real people, not spreadsheet experts
Most financial tools are designed for professionals. LanternTools is designed for anyone who wants to understand their money — clearly and honestly.
Instant results
Results update as you type. No submit button, no waiting, no page reload.
Charts and breakdowns
See your growth over time in a clear chart and a year-by-year table.
Educational content
Every calculator page includes plain-English explanations, worked examples, and FAQs.
No data collected
All calculations happen in your browser. We never store your financial inputs.
Works on any device
Fully responsive design that works equally well on phone, tablet, or desktop.
Global-ready
Use any currency amount. The maths applies everywhere in the world.
Compound interest: your money earning money
When you earn interest on your interest — not just your original deposit — your money grows exponentially rather than in a straight line. Over 20 or 30 years, the difference is enormous.
For example: £10,000 saved at 6% for 30 years grows to £57,435 with simple interest — but with compound interest it reaches £60,226. Add a modest monthly contribution of £200, and the total becomes £228,912. That's the power of compounding.
Compound growth, no additional contributions. Results are illustrative.
Guides to help you understand your money
Plain-English explanations of the financial concepts behind every calculator.