What Percentage Is Each Letter Grade? A Middle School Teacher Breaks Down Common Scales
I was stacking progress reports at the end of a parent-teacher conference last month when Mia, a mom of one of my 8th graders, lingered by my desk, twisting her water bottle cap back and forth. Her daughter Lila was leaning against the hallway wall outside, scrolling TikTok and trying not to listen. Mia pulled a crumpled algebra test out of her purse, the edge frayed from being folded and unfolded for three days. “Lila’s been asking me about this nonstop,” she said. “She got an 89.4 percent here, and your online grade book says it’s a B+. I always thought 89 and above was an A-, but I haven’t been in middle school in 30 years. Can you just tell me what percentage lines up with each letter grade? It feels like the rules changed since I was here.”
I nodded, because I get this question at least three times a semester. When I started teaching 12 years ago, I student taught at a district that used a totally different grading scale, and I confused half my parents the first year when I marked a 92% as a B+ instead of an A. I even got a call from a grandparent who insisted I’d failed his grandson, because when he went to school 90% was an A, end of story. Now I keep the scale written at the bottom of every syllabus, but most parents don’t get that far into the 3-page document that lists late work policies and supply lists, so I don’t take it personally when people ask.
Lila pushed off the wall and stepped into the doorway at this point, hovering. “I need a 3.8 GPA to get into the high school honors biology track next year,” she said, not making eye contact. “If this stays a B+, that’ll bring my overall math grade down, and I’ll miss the cutoff.” I pulled up her semester average on my computer, tapped the screen to show both of them. Right now, it was sitting at 89.6 percent, which rounds up to 90 for the final letter grade, so she’d get an A- regardless of the test score. She exhaled, pulled her hoodie strap, and asked if she could go get a granola bar from the vending machine by the gym. We said yes, and turned back to talk through the breakdown.
Most people want a straight answer, and the truth is there’s no one universal scale, but there is one that’s by far the most common in U.S. public K-12 schools right now. It’s the 10-point scale with plus/minus grading, and it breaks down like this: A+ is 97 to 100 percent, A is 93 to 96, A- is 90 to 92. B+ is 87 to 89, B is 83 to 86, B- is 80 to 82. C+ is 77 to 79, C is 73 to 76, C- is 70 to 72. D+ is 67 to 69, D is 63 to 66, D- is 60 to 62, and anything below 60 is an F. That’s what my district uses, and it’s what I’ve seen at 8 out of 10 neighboring districts I’ve worked with or talked to.
But there are common variations that trip people up all the time. Some small private high schools and colleges use a tighter 7-point scale, where an A starts at 93 percent, a B starts at 85, so a 91 percent that would be an A- on the 10-point scale is a B+ on that one. Some schools don’t give out A+s at all, or don’t do Ds, and just go straight from C to F. A lot of schools round decimals differently, too—some round anything above 89.5 up to a 90, which would have turned Lila’s 89.4 into a B+ and 89.5 into an A-, exactly the kind of tiny difference that changes a cumulative GPA.
Even as a teacher, I’ve been caught off guard by this. When my oldest son started 6th grade last year, I opened his first report card and saw a B+ next to an 88 percent, and I had to pull up the school handbook to double check the scale. When I was Lila’s age, we didn’t do plus/minus grading at all—80 to 89 was a B, 90 to 100 was an A, no in between. So it’s normal to be confused.
The practical thing to do, if you’re confused about your kid’s grade, is not to argue based on the scale you remember. First, pull up the course syllabus on your parent portal—almost all teachers post the grading scale there, even if it’s buried at the bottom. If you can’t find it, send a one-line email: “Can you share what the percentage cutoffs are for letter grades in your class?” It takes two seconds for a teacher to reply, and it clears up all the confusion before anyone gets stressed over a difference in rules.
If your kid is a fraction of a percent below a cutoff that matters—for honors, a scholarship, or even just that A they’ve been working for—ask if there’s a small extra credit opportunity to make up the gap. Most teachers I know would rather let a student do a 10-minute extra problem set or write a short paragraph about what they learned than see a kid lose an opportunity they’re that close to getting. I did that just last semester for a senior who was 0.2 percent below the cutoff for a $10,000 merit scholarship, and we got her over the line in a week.
Mia typed the standard scale into her phone notes when we finished, and laughed that she’d spent a whole week worrying over a rule she’d learned wrong decades ago. Grading scales aren’t a very exciting topic, and I still think they’re a pretty clunky way to measure what a kid actually understands about algebra or reading or anything else. Small differences in cutoffs can feel arbitrary, and there are still days I wish we could lean more on what kids can actually do than the percentage they earn on a single test. But this is the system we have right now, and it’s the one that determines eligibility for all kinds of opportunities kids care about. Knowing the numbers ahead of time doesn’t fix everything, but it takes a lot of the unnecessary stress out of the end of the semester.
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