Rubric Score to Grade Converter

A student meets the standard on every criterion. A 4-point rubric with four criteria, scored 3, 3, 3, 3, totals 12 of 16. As a straight percentage that is 12 ÷ 16 × 100 = 75%, a C on the College Board chart. On a 50% floor scale the average of 3 becomes 50 + (3 − 1) ÷ (4 − 1) × (100 − 50) = 83.3%, a B. Ontario’s chart reads level 3, its provincial standard, as 73–76%, which it reports as a B. Marzano’s book converts each 3.0 to 90% (Table 6.3) and gives an average of 3.0 an A− (Table 6.1): 90%, A−.

Matching Moodle. Moodle’s documentation scores two 1–4 criteria at 2 and 3 and gets (2 − 1 + 3 − 1) ÷ (3 + 3) = 50%, because it maps the lowest possible score to 0. That is the floor scale with the floor set to 0%. The same paper is 5 ÷ 8 = 62.5% as a straight percentage.

The common mistake: dividing the rubric total by the maximum and stopping there. On a 1–4 rubric the lowest score a student can get is already 25%, so a paper of all 2s (“approaching the standard”) comes out at 8 ÷ 16 = 50%, an F, and all 3s at 75%, a C. With a 50% floor, all 2s are 66.7% (a D on the College Board chart) and all 3s 83.3% (a B); on Ontario’s chart level 2 is 63–66%, a C.

Percentage grades were questioned almost as soon as US high schools adopted them. In 1912 Daniel Starch and Edward Charles Elliott gave the same two English papers to 147 high school teachers; the marks ranged from 64 to 98 on the first paper and from 50 to 97 on the second. When they repeated the study with geometry papers and 128 mathematics teachers, one paper drew marks from 28 to 95. Schools moved to scales with fewer, larger categories, such as A to F (as told by Thomas Guskey in “The Case Against Percentage Grades”, Educational Leadership, 2013).

A rubric is one of those few-category scales: each level describes the quality of the work. Guskey points out that a percentage scale with a pass mark of 60 or 65 spends nearly two-thirds of its range on degrees of failure, so dividing a rubric score by its maximum pushes “meets the standard” down to a C. Minimum-grade policies are one response: Guskey, Doug Fisher and Nancy Frey (Educational Leadership, 2024) report that most set the lowest grade at 50% and some at 60%, and Fairfax County Public Schools in Virginia converts quarter averages below 50% to 50%. The floor scale here applies that idea to a rubric, stretching the lowest level to the floor and the top level to 100%.

Ontario wrote a conversion into policy. Its Growing Success document (Ontario Ministry of Education, 2010) defines four achievement levels, with level 3 as the provincial standard, and aligns each level with letter grades for grades 1 to 6 and with percentage marks for grades 7 to 12, from level 1− at 50–52% to level 4+ at 95–100%. Learning platforms take their own line: Moodle’s documentation explains that its rubric formula maps the lowest possible score to a grade of 0, which it notes may differ from how a teacher intuitively reads a rubric. None of these is a universal rule, which is why the tool shows them side by side.

Robert Marzano’s Formative Assessment & Standards-Based Grading (Marzano Research Laboratory, 2010) gives two conversions in chapter 6, “Grading and Reporting”. Table 6.1 (p. 106) turns the average scale score across goals into a letter, from A+ at 3.75–4.00 and A− at 3.00–3.25 down to D− at 1.00–1.25 and F below 1.00; page 105 gives a whole-letter version (A 3.00–4.00, B 2.50–2.99, C 2.00–2.49, D 1.00–1.99). The book’s own examples put an average of 2.35 at C+ and 2.65 at B−, and Table 6.2 (p. 109) names the levels: 4.0 and 3.5 Advanced, 3.0 and 2.5 Proficient, 2.0 and 1.5 Basic, 1.0 and below Below Basic. Table 6.3 (p. 110) converts scores to percents (4.0 is 100, 3.5 is 95, 3.0 is 90, 2.5 is 80, 2.0 is 70, 1.5 is 65, 1.0 is 60 and below 1.0 is 50), and the teacher first converts each score and then averages the percents: 2.5, 3.0, 2.0, 4.0, 3.0 and 3.5 become 80, 90, 70, 100, 90 and 95, an average of 87.5%. Marzano calls the cut points arbitrary decisions about where one grade ends and the next begins, and offers Table 6.3 “or an adaptation of it”. Table 6.3 lists only whole and half points, so the tool reads a score between rows by the lower row and treats 0 and 0.5 as below 1.0 (50%): even a zero converts to 50%. Letters come from the unrounded average, and an average between two bounds, such as 3.255, takes the lower band. Some online summaries (for example Colleague.ai, 2025) attach different percentages to Table 6.1’s bands; those are not in the book and are not used here.

Sources: Ontario Ministry of Education, Growing Success (2010), p. 40; Robert J. Marzano, Formative Assessment & Standards-Based Grading (Marzano Research Laboratory, 2010), Table 6.1 p. 106, Table 6.2 p. 109, Table 6.3 p. 110; Moodle Docs, “Rubrics”; Thomas R. Guskey, “The Case Against Percentage Grades”, Educational Leadership 71(1), 2013; Guskey, Fisher and Frey, “The Unwinnable Battle Over Minimum Grades”, Educational Leadership 82(2), 2024; Fairfax County Public Schools, secondary grading and reporting; letter scales from College Board BigFuture, Fairfax County and Florida Statutes §1003.437.

This converter turns rubric scores into a grade several ways at once: a straight percentage, a floor scale with the floor you choose, and, for rubrics with a top score of 4, Ontario’s published level chart and the conversion tables in Robert Marzano’s Formative Assessment & Standards-Based Grading (or Moodle’s formula when those don’t apply). It handles rubrics from 2 to 10 points starting at 0 or 1, up to 30 criteria, half-level scores and weighted criteria, gives letters from a scale you pick or type, and lists every possible total in a chart you can copy into a spreadsheet or print.

It is for teachers turning rubric marks into report-card grades, departments agreeing a common conversion, and students and parents checking how a rubric became a percentage. Everything runs in your browser; no scores are sent anywhere.

Related tools: EZ Grader, Grade Calculator, and Grade Curve Calculator.