There is no single update day. Creditors report on their own schedules, so your score is a moving snapshot. Some creditors report weekly, some monthly, and no two on the same date. The underlying data shifts constantly, and your score can move day to day without anything dramatic happening. That is normal. Credit Karma is a reasonable free tool for tracking the trend, meaning whether your credit is generally heading up or down over time. The trap is treating its number as the score a mortgage lender will use. Its accuracy also depends on your range: below 700 it tends to run optimistic, often by 20 to 30 points, while above 700 the gap shrinks to roughly 3 to 5 points, so it gets fairly reliable for higher-credit borrowers. Use it to watch direction, and to confirm your paydown efforts are working. When it actually matters, like knowing whether you clear a program's score threshold, the number that counts is the mortgage-specific score a lender pulls from all three bureaus, which can differ from anything a free consumer app shows you.