I don't want to get into a argument over this and there are trade secrets that I cannot disclose by contract but I will tell you that if your score is 700 and you start to churn say goodbye to good apr's in the near future and mortgages will get expensive. 10% is not a set rule and it actually can depend on the model the bank uses. All credit card companies do not rely on the credit bureau score. All scores are not the same, since there are now 4 models in operation, one for each bureau and one that is hoped to be a standard (it is worse than the others IMHO) Also some cc's have their own and use it in conjunction with and/or without regard to the others. If you are in the 790+ range then it is about 10% of the score. If you are less, it is more. In the 600 pt range it amounts to about 10 pts +/- for each hit. The score grows over time without inquiries but NOT very fast. The score drops with inquiries and all factors play into the amount of drop. Do not think for one minute that I or anyone else that has actual knowledge of the program, will disclose enough details for you to figure it out as all have signed very strict documents about this.