What Percentage Is Each Letter Grade? A Teacher Breaks Down Common Grading Scales
Last Tuesday, I got a text from my neighbor Liz asking if I could stop by after school. Her 10th grade daughter Mia had just gotten her first algebra test of the year back, and they were both confused enough to pull in a second opinion. I walked in to the smell of microwave popcorn, a half-eaten plate of Goldfish crackers on their kitchen table, and Mia’s crumpled test paper splayed open between them, a red B+ scrawled at the top next to 88%.
Mia leaned back in her chair, scuffing her sock on the leg of the table. “My middle school told me 87 and above was an A-, right? So why is 88 a B+ here? Did my teacher mess up?” Liz nodded, pulling out her phone where she had three different grading scales pulled up from random Google searches. “One says 88 is a B+, one says it’s an A-, one doesn’t even have pluses and minuses. How am I supposed to know what this means for her GPA when she applies to college next year?”
That’s the question I get more than almost any other as an 8th grade teacher, even more than “how do I help my kid study for midterms?” Most parents assume there’s a universal standard for what percentage lines up with A+, A, A-, B+ and so on. But the truth is, there isn’t one – and that confusion leads to a lot of unnecessary stress for kids and parents every school year.
We pulled up Mia’s high school student handbook together, the one linked on the parent portal, and found the scale printed clear as day in the back. That’s the first thing I tell anyone now: check your own school’s official information first, don’t rely on a random Google result from a district three states away. That said, most US public schools fall into one of two common scales that are easy to remember.
The most widely used right now is the 10-point plus-minus unweighted scale. On that scale, A+ runs 97-100%, A is 93-96%, A- is 90-92%, and so on down the line. Then B+ is 87-89%, B is 83-86%, B- is 80-82%. C+ is 77-79%, C is 73-76%, C- is 70-72%. D+ is 67-69%, D is 63-66%, D- is 60-62%, and anything below 60% is an F. That’s the scale Mia’s high school uses, which is why her 88% was a B+ – that matched the official rule, it wasn’t a teacher mistake.
The second most common is the 7-point scale, used by a lot of private high schools and colleges. On that scale, A+ (if the school uses A+ at all) is 98-100, A is 94-100, A- is 90-93, and then B+ is 87-89, same as the 10-point scale from there down. So on that scale, 88 would still be B+, but 92 is an A- instead of an A like it would be on the old 10-point scale without plus/minus. Some small schools don’t use pluses and minuses at all, and just do a straight 10-point scale: 90-100 is A, 80-89 is B, 70-79 is C, and so on.
After we sorted that out, Liz asked why it matters anyway, beyond the immediate confusion. The big thing most parents care about is how it impacts GPA, right? On the standard 4.0 unweighted scale, most schools line it up like this: A+ is 4.0 (a small number give 4.3, but it rarely changes overall GPA enough to matter), A is 4.0, A- is 3.7, B+ is 3.3, B is 3.0, B- is 2.7, and so on down. So a 1% shift that moves you from an A- to a B+ only drops your GPA by 0.3, which for one test is barely a blip on your overall semester average. But when you don’t know the scale, that one test grade can feel like a disaster.
I reminded Liz of my own 7th grader, who came home upset last month with an 89% on a history test, convinced he’d ruined his honor streak. I use the 10-point plus-minus at my school, so I automatically assumed 89 was a B+, but his history teacher uses the 7-point scale, where 89 is still an A-. It dropped his overall average by 0.1, which didn’t even change his final letter grade for the quarter. He spent three hours stressing over nothing just because we assumed the scale was the same everywhere.
The small, concrete thing I started doing two years ago, that I tell all parents to do, is pull up your school’s grading scale at the start of the year and save a screenshot to your phone notes. It takes two minutes, and you don’t have to think about it again. If the scale isn’t posted online, send a one-sentence email to the front office or your kid’s teacher: “Can you share the official grading percentage scale for letter grades?” No one minds answering that – it’s a common question, and most teachers have it copied and ready to send anyway.
By the time we finished sorting through everything, Mia grabbed her soccer bag slung over the back of the chair and said she had to leave for practice. She shrugged when we told her the grade was correct, just different from what she was used to, and said she’d study a little harder for the next quiz. Liz and I stayed at the table, finishing our cold coffee, and she said she had no idea how much variation there was from school to school.
I told her I still double check sometimes when I sub at the high school across town. There’s no national rule, and there probably never will be, since every district sets its own policy. But that 2-minute check at the start of the year, or even when a confusing grade comes home, saves hours of the kind of stress that doesn’t help anyone. It doesn’t make grading perfect, and it doesn’t change the fact that one test score never tells you everything your kid knows. But it does take the confusion out of the numbers, which is more than enough most days.
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