Straight answers
What calculator can I use on the SAT?
You don't have to bring one: a Desmos graphing calculator is built into the Bluebook testing app and is available for the entire math section — there is no longer a no-calculator part. You may also bring your own calculator, as long as it's on the College Board's approved list.
The built-in graphing calculator is genuinely capable — it graphs functions, finds intersections, and solves equations visually — but only if you already know how to drive it. Students who first open it on test day usually fall back to arithmetic they could have done faster by hand. If you plan to rely on it, practice with it in advance until the keyboard shortcuts are automatic.
Bringing a familiar physical calculator is a reasonable backup and often the faster choice for routine arithmetic. Check the College Board's published approved-calculator list before test day; the general shape of the rules is that most graphing and scientific calculators are fine, while anything with a QWERTY keyboard, internet access, a camera, or that makes noise is not. Phones and tablets never count as calculators.
If you bring your own, bring fresh batteries too. Test centers are not required to supply replacements, and a dead calculator mid-section is a self-inflicted wound.
The strategic point most students miss: many math questions are faster without any calculator at all. Reaching for one reflexively costs seconds that add up across 44 math questions. Practice deciding when to use it, not just how.