Financial Calculators

Compound interest, mortgage amortization, savings goals, and investment returns. Each calculator uses the standard financial formula for that calculation — shown on the page with the formula and worked example. No ads, no login, results stay in your browser.

Financial calculators — compound interest, savings and investment tools

Why Use a Financial Calculator?

Most financial decisions involve compounding numbers. A 0.5% difference in interest rate can mean thousands of dollars over 20 years. These calculators show the exact numbers, with formulas and worked examples on each page.

Compound Interest

The most powerful force in personal finance. Even a 1% higher return compounded monthly over 30 years turns £10,000 into £20,000 instead of £13,000. Use the compound interest calculator to see your exact growth trajectory.

Simple Interest vs. Compound

Car loans, personal loans, and some savings bonds use simple interest (I = P × r × t). It's predictable and linear. The simple interest calculator gives you the total cost of a loan or the exact return on a flat-rate savings product.

Savings Goals

Whether you're building an emergency fund, saving for a car, or hitting a retirement number — the savings calculator tells you exactly how long it takes or how much to save each month to reach your target.

Common Financial Questions

What is the Rule of 72?

Divide 72 by your annual interest rate to estimate how many years it takes for an investment to double. At 6% annual return, your money doubles in roughly 12 years (72 ÷ 6 = 12). It works for any compounding investment.

How much should I save each month?

The 50/30/20 rule allocates 50% to needs, 30% to wants, and 20% to savings. Your actual target depends on income, timeline, and existing assets. Use the savings calculator to model different scenarios.

What is a good interest rate for savings?

In 2025, competitive high-yield savings accounts offer 4–5% APY in the US and 4–5% AER in the UK. Anything above the current base rate (set by the Federal Reserve or Bank of England) is considered good. Always compare the AER (Annual Equivalent Rate), not just the headline rate.

Related Articles

→ How Compound Interest Works: The Complete Guide → How to Calculate Compound Interest: Formula & Examples → How Much Will Your Savings Grow? The Mathematics of Saving

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