Before we discuss what SAT scores "mean," we need to discuss how the SAT is scored and graded.
First, how it is scored: A correct answer on a multiple choice question receives one raw point. An omitted (unanswered) question receives no credit. An incorrect answer receives no credit in addition to a deduction of a quarter of a point. (This is not true of the grid-ins. You can guess on these with no penalty.)
This peculiar scoring scheme is another aspect that makes the SAT different from almost every test you’ve taken in your school career, and it will be a feature of test design that you will probably never see again. The -1/4 penalty is a statistical correction to account for guessing; it is sometimes called the "random guessing penalty."
This video, SAT Foundations #2: Guessing and Scoring, covers how the SAT is scored and the guessing strategy that maximizes your score.
After the right and wrong answers are tallied, the raw score for each section (math, reading, and grammar) is converted into a scaled score from 200-800. (The grammar raw score is combined with the 0-12 score on the essay to yield the 200-800 Writing score). How the raw score converts to the scaled score changes from test to test; it depends on a number of complex statistical thingamajigs that the College Board cares about and we don't. Adding the three 200-800 section scores gives the 600-2400 total score.
When you send your scores to colleges, every college will treat them differently. As discussed earlier, some allow you to use Score Choice to send only the scores you want. Other require all the scores. Once they have those scores, some schools look at each test individually, others look at your highest total score, while still others calculate your superscore.
Superscoring is taking the highest scores for the math, reading, and writing sections, even if those scores come from different tests. For instance, take these three test scores:
Math: 500 Reading: 620 Writing: 450 Total: 1570
Math: 510 Reading: 600 Writing: 500 Total: 1610
Math: 590 Reading: 600 Writing: 510 Total: 1700
A college that superscores would actually add the 590 Math, 620 Reading, and 510 Writing to give you a total score of 1720, higher than any of your "actual" SAT scores. This is useful, but remember that other applicants receive the same benefit.
A 1790 or 2250 is meaningless without context - what do these scores "mean"? First, remember that you can’t officially pass or fail the SAT. I suppose you can "fail" if you are shooting for a 600 Math but miss the mark by 100 points. Your success or failure is thus defined not by some external measure but by your goals and expectations.
The key to understanding the significance of certain SAT scores is to first realize that the test isn’t graded absolutely. In school, you are essentially competing with yourself (or against your teacher) for a particular grade. If you get 100, congrats! You're "perfect." If you get a 40, you fail and won’t get credit for the course. There are well defined bars for competence and incompetence, and how well your friends do is irrelevant when it comes to your possibility of graduating.
But the SAT is different: it is graded relatively. A 1630 or 2230 or 1220 has no meaning outside of what your competitors (other students who took the test) scored. In a concrete way you are competing directly against other students who are taking the test. This makes sense given that you're also competing for them for spots in select colleges, and the SAT is just one measure that helps college sort through the applications in search of the most desirable students.
So the score itself doesn't really matter - what matters is the 'percentile' on your SAT score report. A percentile tells you the percent of students whom you outscored. For instance, if you get a score in the 60th percentile, that score was higher than the scores of 60% of your competitors. Whether the score was 2000 or 1800 or 2200 is irrelevant - what matters is the way you stack up against fellow applicants.
Pushing aside what scores mean for getting into college, let's discuss what the SAT means on a deeper, more fundamental and personal level. In short: does the SAT measure something innate about you, i.e. your intelligence, academic ability, or even your potential for success in life?
This is one aspect of the turbulent controversy about what the SAT allegedly measures, about whom it may be biased for or against, and about whether the test is useful or fair at all. Despite the many criticism levelled against the test, to say that the test is essentially an empty exercise is too far in the opposite direction from the opinion that the SAT is all. Test prep companies and others who say the SAT measures only "how good you are at taking the SAT' are doing a disservice to their students and glossing over a complex psychometric issue. The SAT does measure something of value, else colleges would not use it for the all-important admissions process.
I think the SAT does measure some combination of 'learned' and 'innate' abilities, but trying to tease out the balance between the two is folly. It does test mathematical, grammar, and vocabulary knowledge that you've built up over years of study, but the SAT also tests some kind of abstract "reasoning ability", or how well you can think and solve a problem, especially when the path to the solution is unclear or unfamiliar.
The mistake people make is thinking that since the SAT measures reasoning ability, it must be a measure of some innate quality of a person, like IQ or g. This makes students, parents, teachers, and others perceive the test as some kind of divine oracle that reveals the inherent ability of a student and thus her potential for success. It becomes a referendum on a student's entire person and on his entire future. This is a severely damaging view.
Regardless of what may be "innate," all that matters is that academic SAT skills can be improved. I believe that a score of 1000 simply means that you scored 1000 on the SAT right now, not that you are doomed to a 1000 or that you have been stamped with the 1000 mark which determines anything and everything about you.
This line of reasoning also suggests a similar conclusion about high scores: Don’t be too proud of yourself if you get a 2300+ or some other good score. Sure, it’s a good sign that you’re on track, but it probably means little more than that. It is a milestone on a journey, not some imprimatur of your entire academic and intellectual being. We all have lots to learn, whether we have a 1200 or 2400, and we shouldn't assume anything about ourselves or our potential depending on where we sit in the score spectrum.
How do we know what score to shoot for, then? As I said earlier, what counts as a "good" score for you depends on the colleges you apply to.
Since the test is "norm-based," or graded relatively, what matters is how you compare to the typical admitted student. You can find the mean, median, or middle 50% SAT scores for the colleges that you are applying to and use those as general targets. Note that these "targets" are rarely set-in-stone, “must hit” scores, but rather the median or average score of the previous first-year class. Thus, if you get lower than the average score, you are in good company – almost half of the freshmen did too. You still have a good chance of getting in. If you get a score above this median, congrats! But so did half of the entering freshmen, and it’s no guarantee that you’ll get in on your SAT score alone.
Even getting these average scores is not the full story. You need to pay attention to what colleges specifically say about the SAT because different schools may have different expectations for the test. Some programs, for instance, heavily value the math score but discount the verbal scores (reading and writing); in this case, the total score doesn’t matter so much as the breakdown of that score. Other schools devalue whole sections. We’ll talk more about this later, but for now it’s enough to say that the math and critical reading sections are generally more highly regarded than the writing section.