What Percentage Is Each Letter Grade? A Teacher’s Straightforward Breakdown for Parents
Last Tuesday, my 10th grader slung his backpack onto the kitchen counter after school, dumped out a crumpled stack of tests and his quarter report card, and pointed at the line next to 10th grade biology. “I added up all my points, that’s 89.2% total. Why is this an A-? I thought 90 was A-.” He brushed a Cheeto crumb off the paper onto my half-empty coffee mug, and I leaned back. I get this question at least 10 times a year—from my own students, from my kid’s friends’ parents, from neighbors who know I teach high school. No two schools seem to do it the same, so it’s no one’s fault they’re confused.
I was loading the dishwasher that night when my neighbor Stacy texted a screenshot of her 8th grader’s algebra test. A 92% written in red at the top, with a B next to it. “Is this normal? I thought 90 was an A. Did the teacher grade wrong?” She’d already spent an hour spiraling that her kid was falling behind, when the only issue was a different set of cut offs.
I pulled the grading binder I’d brought home to enter end-of-quarter scores out of my bag and laid it on the counter next to my son’s report card. The most common system used in U.S. public middle and high schools right now is a 10-point unweighted scale with plus and minus modifiers. I walked him through the standard breakdown: An A+ is usually 97 to 100 percent, an A is 93 to 96 percent, and an A- lands at 90 to 92 percent. From there, the pattern stays consistent for Bs, Cs, and Ds: B+ is 87 to 89, B is 83 to 86, B- is 80 to 82, C+ 77 to 79, C 73 to 76, C- 70 to 72, D+ 67 to 69, D 63 to 66, D- 60 to 62. Anything below 60 percent is an F.
That’s the baseline, but almost every school tweaks it a little. Some districts want A+ to be extremely rare, so they bump the cut off up to 98 percent. Others hand out A+ starting at 95, to reward more students for high performance. My sister’s kids attend a small private school that doesn’t issue A+ at all—the highest grade you can get is an A, which starts at 93 percent. Some schools skip plus and minus grading entirely, for a simpler system: A is 90 to 100, B is 80 to 89, C 70 to 79, D 60 to 69, and anything below 60 is an F. That’s the system I used when I was in middle school, back in the 1990s.
A small number of private and parochial schools still use an older 7-point curved scale, which is what Stacy’s kid is on. On that scale, an A starts at 94 percent, and a B falls between 86 and 93 percent. That 92 percent her son earned was always going to be a B, no mistake from the teacher. I texted that explanation to Stacy, and she texted back a sigh of relief. She’d been drafting an angry email to the teacher before she checked in with me.
What surprises most parents is that there’s no national standard for letter grades. Each district, sometimes even each individual school, sets its own scale. That’s why a B at one high school could be an A at the school 10 minutes down the road. I remember when my district switched from the old no-plus/minus system to our current scale 12 years ago, we got dozens of emails the first report card period from parents who couldn’t believe their kid with an 89% had a B+, not an A- like they expected.
Over the years, I’ve picked up a few small, low-effort habits that help parents avoid this confusion. First, pull up the student handbook or your kid’s course syllabus during the first week of school. Almost every school posts their full grading scale right there, so bookmark it in your phone instead of guessing later. If you can’t find it, shoot a 1-sentence email to the front office or your kid’s teacher to ask—they’ll be happy to send it over, and it takes way less time than stressing over a confusing grade later. Second, if you see a letter that doesn’t match the percentage you expected, don’t assume the teacher made a mistake. Ask what the school’s grading scale is before you ask for a regrade. Nine times out of ten, it’s just a different cut off, not an error adding up points. Third, don’t lose sleep over a 1 percentage point difference between grades. If your kid has an 89.8% that gets an A- instead of an A, that’s usually less than half a question off on a final test. It doesn’t mean they’re not mastering the material, it just means they landed on the wrong side of an arbitrary line someone at the district office set.
After I showed my son our school’s scale, he shrugged, folded his report card back up, and headed to the living room to play Minecraft with his friends. He’d been worried he’d messed up the quarter, and once he knew the numbers lined up with the grade, he moved on. I used to stay up late worrying about adjusting my grading to hit cut offs for students, but now I don’t overthink it. The letter is just a quick way to summarize how a kid is doing, not a perfect judgment of how much they’ve learned.
Last week, I got an email from a parent asking if I could round her daughter’s 89.4% up to an A-, because it would bring her GPA up just enough to qualify for honor roll. I told her our school doesn’t allow rounding for grade cut offs, and she was disappointed. But I also told her that her daughter aced every lab practical all quarter, and could explain cell respiration better than most of my former college students. The percentage and the letter are just rules we made up, after all. They’re helpful for getting a quick picture, but they don’t tell you everything you need to know.
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