Should I use letter grades, raw percentage bands, or a standards-based 4-point scale?

Letter grades (A through F) are the default in most US K-12 and university gradebooks because they roll up cleanly into a GPA. Percentage bands with named levels (Excellent, Proficient, Approaching, Below) work well when you want to describe performance qualitatively without committing to a letter or GPA value, common in workshops, short courses, and professional training. A standards-based 4-point scale (1 = beginning, 4 = exceeds) is the dominant model in standards-aligned K-8 classrooms and increasingly in high schools that have moved away from averaging. Pick the one that matches what your school requires on report cards. If you have a choice, match the cognitive frame you want students to bring to feedback.

How do I decide where to set the cut score between B and A?

The traditional US scale uses a 90-80-70-60 rule (A starts at 90, B at 80, and so on) but there is no national mandate and many schools use tighter or looser bands. A common variation is the 93-85-77-70 scale, which raises the A threshold and matches the more selective grading found at competitive high schools and universities. If you teach a course with frequent low-stakes formative assessment, a stricter scale rewards consistency. If you teach a course with high-stakes single-shot exams, a more generous scale absorbs measurement error. Whichever you choose, publish the scale before the first assessment and apply it consistently across every student in the section.

What is the difference between standards-based grading and a traditional letter scale?

Traditional letter grading averages every score across the term, so an early fail can drag a final grade down even after a student demonstrates mastery. Standards-based grading evaluates each learning standard separately on a small ordinal scale (typically 1 to 4) and uses the most recent or most consistent evidence, not the average, to report the final level. The 4-point scale used in this tool follows the common rubric: 4 means the student exceeds the standard, 3 means the student meets it, 2 means partial understanding, and 1 means the standard is not yet evident. SBG works best when paired with clear performance descriptors and an explicit reassessment policy, both of which this tool helps you draft.

How do I know my scale has no gaps or overlaps?

A valid scale covers every possible score from 0 to 100 with exactly one band, leaving no gaps and no overlaps. A gap means a score lands outside every band (for example, the band above ends at 79 and the next band starts at 81, so a score of 80 has no grade). An overlap means a single score qualifies for two grades (for example, B is 80 to 90 and A is 90 to 100, so a 90 is ambiguous). This tool flags both errors in real time as you edit the boundaries, so you can fix them before publishing the scale. The convention used here is inclusive lower bound and inclusive upper bound at the top of the scale; intermediate bands meet at integer cut scores with the higher grade winning the tie.

Can I use this with my school gradebook and report card system?

Yes. The output of this tool is a policy table you can paste into your syllabus, share with parents, and use as the scale definition when configuring any gradebook. Most school information systems, including OpenEduCat, let you define a custom grading scale per course or per term with the same fields this tool generates (letter, minimum, maximum, GPA value). Once the scale is defined in the system, raw scores entered against assessments are converted to letter grades automatically and rolled up into report cards and transcripts without any manual conversion. This removes the spreadsheet step and ensures every teacher in a department applies the same scale.

How is this different from the grading rubric builder?

A grade boundary scale defines how raw scores convert to grades across an entire course (for example, 85 percent becomes a B). A rubric defines how to assign a raw score to a single assignment by describing what each performance level looks like on each criterion. You need both. Use the grading-rubric-builder tool to design the rubric you will apply to each assignment, and use this grade boundary maker to define the course-level scale that converts the totals from those rubrics into final grades. Many teachers publish both together in the syllabus, the rubric explains how individual work is judged and the boundary table explains how the term grade is computed.

What is the lookup function and when would I use it?

The lookup field at the bottom of the tool lets you enter any percentage and instantly see which band it falls into using the scale you have just built. This is useful for quick checks while grading (does 84.5 still round up to a B on my scale, or have I set the B cutoff at 85?) and for testing edge cases before you publish the scale. It is also a fast way to answer student questions during conferences without having to scan the table. The lookup uses the same boundary logic as the printed scale, so anything the lookup returns is exactly what your published policy will assign.

Grade Boundary Maker

Build a custom grading scale in under two minutes. Pick letter grades, percentage bands, or a standards-based 4-point scale, set your cut scores, and print a clean policy table for your syllabus. Free, no login.

Scale name

Scale type

Letter (A-F)

GPA-ready

Percentage bands

Named levels

Standards-based

4-point scale

Letter grade bands

Letter	Min %	Max %	GPA

Valid scale. No gaps, no overlaps. Ready to publish.

What grade is X%?

Type a percentage to see which band it falls in using your current scale.

Enter a percentage

Jump to preview

Course Grading Scale

Letter grade scale with GPA equivalents

Letter	Percentage range	GPA
A	90% – 100%	4.0
B	80% – 89%	3.0
C	70% – 79%	2.0
D	60% – 69%	1.0
F	0% – 59%	0.0

Generated with the free Grade Boundary Maker by OpenEduCat.

How it works

Pick the scale type that matches what your school requires on report cards. The tool loads sensible defaults (the traditional 90-80-70-60 letter scale, a four-band proficiency rubric, or a 4-point standards-based scale) which you can edit row by row. As you change the cut scores, the tool checks for gaps (a percentage that no band covers) and overlaps (a percentage that two bands claim), and flags either issue in red so you can fix it before publishing.

Use the lookup at the bottom to test edge cases. Type a percentage like 89.5 or 74.9 and confirm which band the score falls into. This is the fastest way to answer the question students always ask, what happens to scores near the cut. When the scale is valid and you are happy with it, click Print to export the policy table as PDF, paste it into your syllabus, or share it with department colleagues.

Related free tools

Grading Rubric Builder — build the rubric you apply to a single assignment, then use this Grade Boundary Maker to define the course-level scale that converts assignment totals into final grades.
Grade Conversion Calculator — convert between GPA, percentage, and letter grade systems once a final grade is computed.
All free teacher tools

Frequently asked questions

A grade boundary is the minimum score required to earn a particular grade. If your scale says a B is 80 to 89, then 80 is the lower boundary for B and 90 is the lower boundary for A. Boundaries matter because they make grading transparent and defensible. A student who scores 79.5 deserves to know in advance whether your policy is to round up, hold the line, or apply a soft buffer near each cut score. Publishing your boundaries at the start of a term, ideally in the syllabus, also protects you from individual grade disputes by making the rule, not the marker, the source of the decision.

Apply this scale automatically in your gradebook

OpenEduCat lets you define a custom grading scale per course, applies it to every raw score entered, and rolls the result up into report cards and transcripts. No spreadsheets, no manual conversion, every teacher on the same scale.

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