How Credit Scores Work and Why They Matter

One number that follows you everywhere

Your credit score is a three-digit number between 300 and 850. A lender you have never met looks at that number and decides whether to give you a loan, what interest rate to charge, and sometimes whether to rent you an apartment or even offer you a job. Understanding how this number is calculated — and why it matters so early — is one of the most practical things you can learn before adulthood.

The most common scoring model is the FICO score, used by about 90% of lenders. Here is exactly what goes into it:

Payment history (35%) — The single biggest factor. Do you pay your bills on time? Even one missed payment can drop your score by 50–100 points. Consistent, on-time payments over years are the most powerful force for a high score.

Amounts owed / credit utilization (30%) — How much of your available credit are you using? If you have a credit card with a $1,000 limit and carry a $900 balance, your utilization is 90% — that is a red flag to lenders. Keeping utilization below 30% (ideally below 10%) signals that you are not dependent on borrowed money to survive.

Length of credit history (15%) — How long have your accounts been open? Older accounts are better. This is why financial experts tell teens to open a secured credit card early — even a card you barely use starts building this history.

Credit mix (10%) — Having different types of credit (credit card, installment loan) shows you can manage various financial tools responsibly. Not critical early on, but it helps.

New credit inquiries (10%) — When you apply for new credit, the lender does a "hard inquiry" that slightly lowers your score temporarily. Applying for five credit cards in a month signals financial desperation to lenders.

Score ranges and what they mean

• 800–850: Exceptional — you qualify for the best rates on everything
• 740–799: Very Good — minor rate differences from Exceptional
• 670–739: Good — most lenders approve you, rates are reasonable
• 580–669: Fair — you get approved for less, pay higher rates
• Below 580: Poor — many lenders decline you, or charge very high rates

The difference between a 620 score and a 760 score on a 30-year mortgage can cost over $100,000 in extra interest over the life of the loan. This is why starting to build credit at 16–17 rather than 22 is genuinely valuable.

Why landlords and employers check credit

Landlords use credit scores to assess whether you will pay rent reliably. A poor score might mean a declined application, a higher security deposit, or a co-signer requirement. Some employers — especially for jobs handling money or finances — also run credit checks as part of hiring. A poor credit history can cost you an apartment and a job simultaneously during an already stressful period.

Checking your own credit does not hurt your score

A common misconception is that checking your credit damages it. Checking your own report (a "soft inquiry") has zero effect on your score. Only hard inquiries from lenders applying for new credit on your behalf affect your score. Check your own credit reports at least once a year — errors on credit reports are more common than people realize, and disputing them is your right.

Start early, benefit for decades

Your credit score is not just a score — it is a financial track record. The habits you build in the next few years become the foundation of that record. Pay on time, keep utilization low, and do not apply for credit you do not need. The compound effect of good credit habits built early is one of the clearest financial advantages available to teens.