Start here

Beginner's Guide

You don't need to be good at math to use these calculators. This page explains how they work, what interest rates mean, and the money words you'll see along the way.

How the calculators work

Fill in the boxes on the left (or at the top on a phone). Every calculator starts with example numbers, so you can see how it works before typing anything.
Results update instantly as you type — there's no button to press. The big number is the main answer; the sentence under it explains it in words.
Tap the ⓘ next to any word you don't know for a one-sentence explanation. They're also all listed at the bottom of this page.
Play with the numbers. The best way to learn is to change one thing at a time — like adding $50 a month or waiting 5 more years — and watch what happens.
Save or share your results with the Share link, Copy results and Export CSV buttons. Your numbers stay in your browser; nothing is sent anywhere.

Remember: these are estimates to help you learn and plan, not financial advice. Real rates, taxes and fees vary.

Which calculator should I use?

Find the question that sounds like yours. If you're just starting out, work through them from top to bottom.

Level 1: Basics

Level 2: Building Wealth

Level 3: Debt & Borrowing

Level 4: Long Game

“Am I saving enough to retire?”Retirement →

Understanding interest rates

What does a percentage rate mean?

A rate tells you how much money is added each year for every $100. A 5% rate means about $5 a year for every $100. On $1,000 that's about $50 a year; on $10,000 it's about $500.

When you save or invest, a higher rate is good — it's money you earn. When you borrow, a higher rate is bad — it's money you pay.

How to type a rate into the calculators

Type the number you see, without the % sign: for 5%, type 5; for 24.99%, type 24.99. Don't convert it to a decimal — we do that for you.

APR vs. APY: what's the difference?

APR is the basic yearly rate. Loans and credit cards show APR.
APY also counts interest earned on interest during the year, so it's a little higher. Savings accounts show APY.
Example: a 5% APR with interest added monthly works out to a 5.12% APY. To compare a savings account with a loan fairly, use the Interest Rates Explained calculator.

Where do I find my rate?

Credit cards and loans: on your monthly statement or in your lender's app — look for “APR” or “interest rate.”
Savings accounts: in your bank app or on the bank's website — look for “APY.”
Investments: there's no fixed rate. Use a long-term average from the table below, and remember real results go up and down.

Typical rates (rough ranges)

These change with the economy and your credit, so always check your actual numbers. They're here to help you pick a reasonable starting point.

Typical rates by type of account or loan
Type	Typical rate	Good to know
Regular savings or checking account	0% – 0.5%	Often close to nothing.
High-yield savings account or CD	About 0.5% – 5%	Rises and falls with the economy.
Credit card	About 20% – 30% APR	One of the most expensive ways to borrow.
Car loan	About 5% – 12% APR	Depends a lot on your credit score.
Federal student loan	About 4% – 8%	Set by the government each year.
30-year mortgage	About 3% – 8%	The range seen over the last 20 years.
Stock market (broad index fund)	About 7% – 10% a year on average	A long-term average, not a promise. Some years are up 20%+, some down 20%+.
Inflation (U.S.)	About 2% – 3% a year	Long-term average; some years are much higher.

Money words, explained

Principal: The original amount of money you borrow, save or invest — not counting any interest.
Interest: The extra money paid for using someone else's money: you earn it when you save, and you pay it when you borrow.
Interest rate: How much interest you pay or earn each year, as a percentage of the amount.A 5% yearly rate means $5 of interest for every $100, every year.
APR (annual percentage rate): The yearly interest rate on a loan or credit card, before interest-on-interest is counted.Loans and credit cards advertise APR. Because interest is usually added monthly, you really pay a bit more than the APR — that true yearly cost is the APY.
APY (annual percentage yield): What you actually earn (or pay) in a year once interest-on-interest is included.Savings accounts advertise APY. For the same rate, APY is always a little higher than APR.
Compound interest: Earning interest on your interest — your balance grows faster and faster over time.Save $100 at 10%: after year one you have $110, and next year you earn 10% on $110, not $100.
Compounding frequency: How often earned interest is added to your balance (for example, monthly). More often means slightly faster growth.
Contribution: Money you add to your savings or investments on a regular schedule, like $200 every month.
Contribution timing: Whether you add money at the start or end of each period. Adding it at the start gives it a little extra time to grow.
Loan term: How long you have to pay back a loan, such as 5 years for a car or 30 years for a home.
Amortization schedule: A payment-by-payment table showing how much of each payment goes to interest and how much pays down the loan.Early on, most of your payment is interest. Later, most of it pays down what you owe.
Balance: How much you still owe on a debt (or how much is in an account) right now.
Minimum payment: The smallest amount a lender requires you to pay each month to stay in good standing.Paying only the minimum on a credit card can take many years and cost a lot in interest.
Extra payment: Any amount you pay above your required payment. It goes straight to the amount you owe, so you pay less interest overall.
Down payment: The cash you pay upfront when buying a home; the rest is borrowed with a mortgage.
PMI (private mortgage insurance): An extra monthly fee most lenders charge if your down payment is under 20%. It goes away once you've paid down enough of the loan.
Property tax: A yearly tax your local government charges homeowners, usually based on the home's value.
Homeowners insurance: Insurance that pays to repair or rebuild your home after damage like fire or storms. Lenders require it.
HOA dues: Monthly fees some neighborhoods, condos and townhomes charge to maintain shared areas.
Inflation: The general rise in prices over time, which means each dollar buys a little less every year.Over the long run, U.S. prices have risen about 3% a year on average.
Purchasing power: How much stuff your money can actually buy. Inflation slowly shrinks it.
Today's dollars: A future amount adjusted for inflation, so you can see what it would buy today.$1 million in 30 years might only buy what about $400,000 buys today.
Real return: Your investment growth after subtracting the effect of inflation — how much richer you actually got.
Rate of return: How much an investment grows in a year, as a percentage. It's an average — real investments go up and down.
CAGR (compound annual growth rate): The steady yearly growth rate that would turn your starting value into your ending value.
Volatility: How much an investment's value jumps up and down from year to year. Higher volatility means a bumpier ride.
Avalanche method: Paying off the debt with the highest interest rate first. It saves the most money.
Snowball method: Paying off the smallest debt first. You see progress sooner, which keeps many people motivated.
Emergency fund: Savings set aside only for surprises, like losing your job or a big car repair — usually 3 to 6 months of essential costs.
Take-home pay: Your pay after taxes and deductions — the amount that actually lands in your bank account.
Needs vs. wants: Needs are bills you must pay (rent, groceries, utilities). Wants are nice-to-haves (eating out, streaming, travel).
FIRE number: How much you'd need invested to live off it — roughly 25 times what you spend in a year.FIRE stands for “Financial Independence, Retire Early.”
Withdrawal rate: The share of your savings you take out each year in retirement. 4% is a common rule of thumb.
Rule of 72: A quick trick: divide 72 by your yearly rate to estimate how many years it takes money to double.At 8% a year, 72 ÷ 8 = about 9 years.
Simple interest: Interest charged only on the original amount, never on past interest.
Day-count basis: Whether a lender treats a year as 365 days or 360 days. Using 360 makes the interest slightly higher.

Ready? Browse all 11 calculators →