How it works
How to use this weighted average calculator
- Enter a value and a non-negative weight on each row you want to include.
- Leave unused rows blank, or add more rows.
- Read the weighted mean, the weight total, and whether that total is 1, 100, or some other relative sum.
Formula
The calculation formula
Weighted mean = Σ(value × weight) ÷ Σ(weight)01
Multiply each value by its weight.
02
Add those products to get the weighted sum.
03
Divide by the sum of the weights.
Worked examples
Example calculations
Credits as weights
80 with weight 2 and 90 with weight 3: (80 × 2 + 90 × 3) ÷ (2 + 3) = 86.
Weights that already sum to 1
10 with weight 0.4 and 20 with weight 0.6: 4 + 12 = 16. The note reports that the weights already form a complete share.
When to use it
Common use cases
- Blend scores that carry different credits or sample sizes
- Average prices by quantity sold
- Check whether weights already form a complete share of 1 or 100
Limits
Assumptions and limits
- Weights are relative. They do not have to sum to 1 or 100.
- A weight of 0 omits that row. Negative weights are rejected.
- A row needs both a value and a weight, or it must be left blank.
Questions
Frequently asked questions
Do my weights need to add to 100?
No. 2 and 3 work the same as 40% and 60%. The calculator reports the weight total so you can see which convention you used.
How is this different from GPA?
GPA converts letter grades to quality points first, then applies credit weights. This tool averages the numbers you type, so it is the general form behind a credit-weighted mean.
Sources
Sources and review
- Wikipedia — Weighted arithmetic mean
Definition of the weighted mean as a weight-normalized sum
Accessed August 25, 2026