FICO scores vary because different credit reporting agencies (Equifax, Experian, TransUnion) maintain separate records of your credit history, and lenders may report information to these bureaus at different times or incompletely. Additionally, FICO produces multiple scoring versions—the classic FICO Score 8 is most common, but FICO Score 9, 10, and industry-specific versions (auto, mortgage) use slightly different formulas that weigh factors like delinquencies, credit utilization, and payment history with varying emphasis. Even within the same bureau and version, timing matters: your score updates as new information arrives, so checking on different dates can show different numbers. Your actual behavior also creates legitimate variation—applying for new credit, paying down balances, or resolving collections will shift scores across bureaus at different rates depending on reporting delays. Lenders may also use alternative scores (VantageScore) or their own proprietary models. This fragmentation is intentional to some degree: FICO maintains different versions to reflect how different industries assess risk, but it creates the confusing situation where you might see three notably different scores from three different sources. The variation is usually small (within 50 points) if your credit history is stable, but can be larger if recent changes haven't been reported uniformly across all bureaus.