Will opening a new credit card to transfer a balance hurt my credit score?

Slightly and temporarily, and usually it's worth it. Applying triggers a hard inquiry that typically costs a few points and fades within a year. The new account also lowers your average age of accounts, another small ding.

But a balance transfer often helps your score more than it hurts, because it adds available credit, which lowers your overall utilization, the bigger scoring factor. If you move $4,000 onto a new $8,000-limit card and don't touch the old cards, your total utilization drops. Just don't close the old cards right after, since that would erase their limits and spike utilization again. The net effect is usually neutral to positive within a couple of months. Simulate it at wealthserene.com/tools/credit-score-simulator.