Dear Liz: I was recently denied a credit card and told my score was 150 points lower than what my credit reports show. Why would this be? Am I being deceived by the credit reporting agencies? It was such a low number that it’s a little hard to believe since I have been approved for other cards recently.

Answer: The creditor that denied you should have told you which score it used and from which credit bureau in addition to the actual number. Lenders employ a variety of different scores, but most use some variation of the FICO formula. Credit card lenders tend to use FICO Bankcard scores, which are on a 250 to 900 scale in contrast to the usual FICO 300 to 850 scale. Your numbers will vary depending on the version and bureau that lenders use. For example, a card company may pull a FICO Bankcard 4 from TransUnion, a FICO Bankcard 2 from Experian or a FICO Bankcard 5 from Equifax, although many issuers use the latest version, which is FICO Bankcard 8.

If that isn’t confusing enough, FICOs aren’t the only scores in town. The scores you get directly from credit bureaus, for example, typically won’t be FICOs. You may have been looking at VantageScores or at a proprietary score. The free scores offered at many websites tend to be VantageScores, which are on a 300 to 850 scale but may not be the same as your FICOs.

If you want a clearer snapshot of where you stand before applying for credit, you can pay $20 at MyFico.com to see a bunch of your FICO scores from a single credit bureau or $60 to see FICOs from all three bureaus.

You may not be able to determine in advance which score from which bureau a lender uses, however. You also should understand that whether a score is good enough may depend on the lender and on the product. Many lenders require higher FICO scores for their better credit card deals, for instance. Sites that track credit card deals may give you some idea of how high your scores generally need to be to get approved, but there are no guarantees.

Your best course is to make sure all your scores are as good as they possibly can be. That means, among other things, paying your bills on time, not letting disputes turn into collections and using your credit cards lightly but regularly. You don’t need to carry a credit card balance to have good scores, and you should try to use 30% or less of your available credit limit at any given time. Finally, apply for credit sparingly, and don’t close credit accounts if you’re trying to improve your scores.