Grade Calculator

How the Calculator Works

The tool supports three distinct grading formats used across American educational institutions. Enter up to 15 component grades, each with an optional weight reflecting its importance toward your final mark.

Weights default to 1 for unweighted calculations—useful when all assignments contribute equally. If your course uses weighted grading, adjust each weight as a decimal (0.5 for 50%, 0.2 for 20%) or whole number. The calculator automatically displays results in your chosen format and can cross-reference against customisable grading scales.

• Letter grades: Map raw scores to A, B, C, D, F plus modifiers
• Percentage grades: Work with 0–100% scales directly
• Point-based grades: Input earned points and maximum possible, then convert to percentages and letters

Weighted Grade Formula

When individual grades carry different weights—such as homework worth 20%, midterms 30%, and finals 50%—use the weighted average formula. This prevents high-stakes exams from overshadowing consistent coursework.

• g — Individual grade value (letter, percentage, or points)
• w — Weight assigned to each grade component
• p — Points earned on an assessment
• pmax — Maximum possible points for that assessment

Worked Example: Percentage-Based Final Grade

Suppose you're finishing a course with three major assessments: an essay (15% weight) scored at 67%, a midterm exam (35% weight) at 75%, and a final exam (50% weight) at 72%. First, convert weights from percentages to decimals: 0.15, 0.35, and 0.50.

Apply the formula:

• 67% × 0.15 = 10.05%
• 75% × 0.35 = 26.25%
• 72% × 0.50 = 36%
• Total: 10.05 + 26.25 + 36 = 72.3%, rounded to 72%

Your weights sum to 1.0, so you skip the denominator division. The final grade is a solid C.

Common Mistakes When Calculating Grades

Avoid these pitfalls when entering data or interpreting results.

1. Forgetting to convert percentage weights to decimals — Teachers often express weights as percentages (e.g., 25%, 50%, 25%), but the formula requires decimals. Divide each percentage by 100: 25% becomes 0.25. Entering them as whole numbers will inflate your result dramatically.
2. Treating point grades like percentages without normalisation — If one exam is out of 50 points and another out of 100, they aren't directly comparable. Always convert each to a percentage first (points earned ÷ maximum points × 100%) before applying weights, or let the calculator handle it automatically.
3. Misaligning weights with course requirements — Some schools use credit hours (e.g., a 3-credit course matters more than a 1-credit elective), while others use contribution percentages that must sum to 100. Check your syllabus carefully—entering arbitrary weights will skew your forecast.
4. Ignoring custom grading scales at your institution — Different universities and regions use different cutoffs. A 90% might be an A at one school but an A- at another. Always confirm your grading scale with your department before trusting letter-grade conversions.

Understanding Letter Grade Thresholds

Most U.S. institutions follow a standard scale, but variations exist. A 75% typically equates to a C, falling within the 70–79% range. Schools using letter modifiers (+ and −) divide this further: C− is 70–72%, C is 73–76%, and C+ is 77–79%.

Your calculator includes editable threshold fields so you can input your school's exact boundaries. If your course handbook specifies that an A requires 92% rather than 90%, adjust the limits accordingly. This ensures your forecast matches your transcript.