Formula
Weighted average = Σ(value × weight) ÷ Σ(weight). If weights are percentages that add to 100, this is the same as adding each value × weight percent ÷ 100.
Study & School
Weighted Average Calculator
Calculate a weighted mean from values and weights for grade categories, credits, survey scores, index components and spreadsheet checks, with contribution lines, total-weight warnings and a printable weighted-average worksheet record.
Calculator
Working calculator
Live result84.508450.00 weighted total ÷ 100.00 total weight · weights total 100
Formula used
Weighted average = Σ(value × weight) ÷ Σ(weight). If weights are percentages that add to 100, this is the same as adding each value × weight percent ÷ 100.
This is the method behind the answer, so the result can be checked rather than simply trusted.Contribution check
84.50
8450.00 weighted total ÷ 100.00 total weight.
| Row | Value | Weight | Value × weight |
|---|---|---|---|
| 1 | 90.00 | 20.00 | 1800.00 |
| 2 | 80.00 | 30.00 | 2400.00 |
| 3 | 85.00 | 50.00 | 4250.00 |
| 4 | 0.00 | 0.00 | 0.00 |
Visual grid
This number is one point on a larger pattern
Weighted Average is not just a final answer. It is a step on a line: before and after, input and output, assumption and result.
Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars
InputFormulaResult
84.50CalculationTime keeps the path visible: the input, the method and the final number belong together.
CalculationTime
Weighted Average Calculation Report
84.508450.00 weighted total ÷ 100.00 total weight · weights total 100
Inputs
- Value 1
- 90 score or percent
- Weight 1
- 20 weight
- Value 2
- 80 score or percent
- Weight 2
- 30 weight
- Value 3
- 85 score or percent
- Weight 3
- 50 weight
- Value 4
- 0
- Weight 4
- 0 optional weight
Method
Weighted average = Σ(value × weight) ÷ Σ(weight). If weights are percentages that add to 100, this is the same as adding each value × weight percent ÷ 100.
- Homework is 90 worth 20, midterm is 80 worth 30 and final is 85 worth 50. Weighted average = (90×20 + 80×30 + 85×50) ÷ (20+30+50) = 8,450 ÷ 100 = 84.5.
Assumptions
- Weights must be zero or positive; rows with zero weight are ignored in the weighted result.
- Weights can be percentages, credits, units or relative importance as long as the same meaning is used across rows.
- If percent weights are intended, check that the total weight is 100.
- The calculator computes a weighted mean only; it does not apply school-specific gradebook rules.
Notes
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
Worked example
Homework is 90 worth 20, midterm is 80 worth 30 and final is 85 worth 50. Weighted average = (90×20 + 80×30 + 85×50) ÷ (20+30+50) = 8,450 ÷ 100 = 84.5.
Professional note
Master’s Tip: write down whether weights are category percentages, credits or arbitrary units. The arithmetic is the same, but the meaning of the result depends on the meaning of the weights.
Regional and unit assumptions
Defaults use a grade-style percent example with weights totaling 100. The formula is general and can also be used for credits, units, frequencies or importance weights.
Assumptions and limitations
- Weights must be zero or positive; rows with zero weight are ignored in the weighted result.
- Weights can be percentages, credits, units or relative importance as long as the same meaning is used across rows.
- If percent weights are intended, check that the total weight is 100.
- The calculator computes a weighted mean only; it does not apply school-specific gradebook rules.
- Missing work should be entered according to the course policy, often as zero if it counts.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Weighted average = Σ(value × weight) ÷ Σ(weight). If weights are percentages that add to 100, this is the same as adding each value × weight percent ÷ 100.
Standard or basis
Defaults use a grade-style percent example with weights totaling 100. The formula is general and can also be used for credits, units, frequencies or importance weights.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: write down whether weights are category percentages, credits or arbitrary units. The arithmetic is the same, but the meaning of the result depends on the meaning of the weights.
Related calculators
Questions
What is a weighted average?
It is an average where some values count more than others. Each value is multiplied by a weight before the total is divided by the sum of weights.
Do weights have to add to 100?
Only if you are using percentage weights. Arbitrary weights such as credits or units are normalized by dividing by the total weight.
Is a weighted average the same as GPA?
GPA can use weighted-average ideas, but official GPA rules depend on grade points, credits, repeats and institution policy.
How do I include a missing assignment?
Follow the course policy. If the missing assignment counts as zero, enter 0 as the value with its normal weight.
What if one weight is zero?
A zero-weight row contributes nothing to the result and is ignored except in the printed input list.
Calculation note
Weighted averages are used whenever some observations should count more than others. In school settings, this often appears as categories, credits or exam weights.
Simple average versus weighted average
A simple average gives every value the same importance. A weighted average changes that by letting one value count more heavily, such as a final exam being worth more than a small homework task.
Percent weights and category weights
Gradebooks often use category percentages that add to 100. In that case, each category contribution is its score multiplied by its percent weight.
Arbitrary weights and credits
Weights do not always have to be percentages. Credits, units, frequencies and importance scores can all be used if the final division by total weight is included.
Common mistake
A common error is adding value × weight products but forgetting to divide by total weight when the weights do not add to 100.
Connection to final grades
Final grade calculators are a special weighted-average problem: the current course grade and final exam score each receive a weight in the overall grade.