What Is a Credit Score and How Is It Calculated?

What Is a Credit Score?

A credit score is a three-digit number, typically ranging from 300 to 850, that represents a statistical assessment of your creditworthiness — the likelihood that you will repay borrowed money on time. Lenders use credit scores to make rapid decisions about loan applications and to set interest rates. Higher scores earn lower rates; lower scores result in higher rates or outright denials.

The most widely used scoring model is the FICO score, developed by Fair Isaac Corporation and used by approximately 90% of top lenders. VantageScore is another widely used model developed jointly by the three major credit bureaus (Equifax, Experian, and TransUnion). While the two models weigh factors slightly differently, both use the same underlying credit report data and generally produce similar results.

The Five Factors and Their Weight

FICO scores are calculated using five categories of information, each weighted differently:

• Payment history (35%): The single most important factor. Every on-time payment strengthens this score; every missed payment, collection, or derogatory mark damages it. Even one 30-day late payment can drop a score by 50–100 points.
• Amounts owed / Credit utilization (30%): The percentage of available revolving credit currently in use. Using $3,000 of a $10,000 credit limit is 30% utilization. Lower is better — experts recommend staying below 30%, ideally below 10%, for the highest scores.
• Length of credit history (15%): How long your accounts have been open, including the age of your oldest account, newest account, and average age across all accounts. This is why closing old credit cards can actually hurt your score.
• Credit mix (10%): Whether your credit file includes a variety of account types — revolving credit (credit cards), installment loans (auto, mortgage, student loans), and retail accounts. A diverse mix signals broader credit management experience.
• New credit / Hard inquiries (10%): Each time you apply for new credit, the lender performs a hard inquiry, which temporarily lowers your score by a few points. Multiple inquiries in a short period (rate-shopping for a mortgage or auto loan) are typically grouped as a single inquiry by FICO.

Score Ranges and What They Mean

FICO scores are divided into ranges that lenders use as rough guidelines for creditworthiness:

• 800–850 (Exceptional): Best available rates on all credit products; easy approval for mortgages, auto loans, and premium credit cards.
• 740–799 (Very Good): Near-best rates; approval for virtually all mainstream credit products.
• 670–739 (Good): Approved for most products at competitive rates; the rough national average falls in this range.
• 580–669 (Fair): Approval possible but rates are elevated; some premium products unavailable.
• 300–579 (Poor): Limited access to mainstream credit; may require secured cards, co-signers, or alternative lenders with high rates.

How Credit Utilization Works in Practice

Credit utilization is the factor you can most rapidly improve. Because it is recalculated based on your current balances each month when issuers report to the bureaus, paying down balances produces nearly immediate score improvements. If your score goal is time-sensitive — you are planning to apply for a mortgage in three months — aggressively reducing card balances is the fastest lever you can pull.

An important nuance: utilization is measured both per card and in aggregate. A card with a $1,000 limit carrying a $900 balance hurts your score even if you have five other cards with zero balances and a combined limit of $50,000. Keep individual card balances low, not just your overall total. If you carry balances, consider asking for credit limit increases — they immediately improve your utilization ratio without requiring you to pay down any debt.

The Impact of Late Payments

A single 30-day late payment can reduce a strong score (780+) by as much as 90–110 points, and the damage persists for years. Late payments remain on your credit report for seven years from the date of the original delinquency, though their impact fades over time as the account ages and you build a stronger subsequent payment history.

The most effective strategy is setting up automatic minimum payments for every account. You can always pay more manually, but autopay prevents the catastrophic score damage of an accidentally missed due date. If you have a late payment on your record and have otherwise maintained excellent payment history since, you can contact the creditor and request a goodwill adjustment — a request to remove the late payment notation as a courtesy. Many creditors honor this request for one-time slipups from otherwise reliable customers.

Building Credit from Scratch

If you have little or no credit history, establishing credit requires a deliberate first step. The most accessible options include:

• Secured credit cards: You deposit a refundable security deposit (typically $200–$500) that becomes your credit limit. Use it for small regular purchases and pay in full each month. Most secured cards report to all three bureaus.
• Becoming an authorized user: Being added to a parent's or partner's established credit card account can instantly add positive history to your credit file, even without ever using the card.
• Credit-builder loans: Offered by many credit unions and fintechs, these loans hold the loan proceeds in a savings account while you make monthly payments. When the loan is repaid, you receive the funds and have a positive installment loan history on your report.

Monitoring and Protecting Your Score

Check your credit reports for free at AnnualCreditReport.com — the only federally authorized free credit report site — which provides free weekly access to reports from all three bureaus. Review them for errors: a Federal Trade Commission study found that 1 in 5 Americans has a verifiable error on their credit report, and one-third of people who dispute errors see their score improve.

Dispute errors directly with the credit bureau reporting the error using their online dispute portal or by certified mail. Bureaus have 30 days to investigate and respond. Also consider placing a credit freeze at all three bureaus — it is free, prevents new accounts from being opened in your name without your knowledge, and can be lifted instantly when you need to apply for credit.