Grade calculator for weighted averages and finals

Work out your grade in seconds

Type your scores in the first tab: your average appears as you type, along with the calculation done on your numbers. The calculator has four uses:

• Grade average: one row per grade, with its total (out of 100 by default) and its weight (1 by default). You can also type “45/50” straight into the score box.
• Final grade needed: the score you need on the final exam to reach the grade you want, and your final grade for each possible score.
• List of numbers: the mean or weighted mean of any list pasted from a spreadsheet, with the median, the standard deviation and other means.
• Convert a score: points turned into a percentage, a score out of 10 or 20, and a letter grade.

It’s free, with no sign-up. Everything is worked out in your browser, which keeps your grades for next time: nothing is sent.

How to calculate an average

The simple average, or mean, is the sum of the values divided by how many there are. With 85, 90 and 78: (85 + 90 + 78) ÷ 3 = 253 ÷ 3 ≈ 84.33.

It gives every grade the same weight. As soon as a test counts more than homework, you need a weighted average.

Weighted grades: categories and weights

Most syllabuses split the final grade into categories. Multiply each grade by its weight, add the results, then divide by the total of the weights:

weighted grade = (grade 1 × weight 1 + grade 2 × weight 2 + …) ÷ (weight 1 + weight 2 + …)

Your grade is 8,680 ÷ 100 = 86.8%, a B on the common scale. Without the weights it would be (92 + 78 + 90) ÷ 3 ≈ 86.67%.

The weights don’t have to add up to 100. If only homework and the midterm have been graded so far, the calculator divides by 50 and gives your current grade: (1,840 + 2,340) ÷ 50 = 83.6%.

Points and percentages

To turn points into a percentage, divide the points earned by the points possible and multiply by 100: 45 out of 50 is 45 ÷ 50 × 100 = 90%. The calculator converts every score this way before applying the weights.

If your class uses total points instead of categories, enter each score with its “out of” and use that same number as the weight: the result is your total points earned divided by the total points possible.

What do I need on the final?

You need your current grade, the weight of the final exam in your course grade, and the grade you’re aiming for:

score needed = (target − current grade × (1 − final weight)) ÷ final weight

With 82% going into a final worth 30% and an 85% target: (85 − 82 × 0.7) ÷ 0.3 = (85 − 57.4) ÷ 0.3 = 92%. If the result is above 100%, the target is out of reach with this exam, and the calculator tells you. The “Use my grades” button fills in your current grade from the first tab.

Letter grades and GPA

• Common US scale: A from 90%, B from 80%, C from 70%, D from 60%, and F below 60%. Many schools add plus and minus grades, or use a stricter scale: your syllabus has the final word.
• GPA: on the usual 4.0 scale, an A is worth 4 points, a B 3, a C 2, a D 1 and an F 0. Your GPA is the average of those points weighted by credit hours. Use the List of numbers tab: grade points as values, credit hours as weights. Our GPA calculator does it from letter grades, with weighted (Honors, AP) and cumulative GPA.

Median, standard deviation and other means

• Median: the middle value once the list is sorted (or the mean of the two middle values). With 62, 75, 78, 81 and 99, the mean is 79 but the median is 78: the median barely moves with one very high or very low score.
• Standard deviation: how spread out the values are around the mean. Two classes can both average 80%, one with scores close together, the other from 50% to 100%. The calculator gives the standard deviation of the whole list.
• Harmonic mean: the right average for speeds. Driving one way at 60 mph and back at 40 mph averages 48 mph, not 50.
• Geometric mean: the right average for rates that compound. Growth of 10% one year and 20% the next is about 14.9% a year.
• Average of percentages: if the groups differ in size, weight each one by its size. 80% of 25 students and 60% of 15 students is 72.5% overall, not 70%.

Averages in Excel and Google Sheets

• Mean: =AVERAGE(B2:B10).
• Weighted average: scores in column B, weights in column C, =SUMPRODUCT(B2:B10, C2:C10) / SUM(C2:C10).
• Median and standard deviation: =MEDIAN(B2:B10) and =STDEV.P(B2:B10), the standard deviation of the whole list, like the calculator. STDEV.S treats the list as a sample and gives a slightly larger number.

To check a spreadsheet, copy the two columns (scores and weights) and paste them into the “Numbers” box of the List of numbers tab: the calculator splits them for you.

More help with math and studying

Nation’s assistants and tools can take it from here:

• Hakim explains and solves math problems, step by step;
• the revision sheet generator turns a course PDF into a study sheet;
• the percentage calculator works out a share, an increase or a discount, with the formula.