Average & weighted average calculator
Build an ordinary or weighted average from your values, with the totals and each weighted contribution shown.
Values and weights
1
2
3
Average
20
- Number of values
- 3
- Sum
- 60
- Range
- 20
- Minimum
- 10
- Maximum
- 30
Arithmetic summary only. No grading policy, missing-data treatment, outlier handling or statistical inference is applied.
Included
- Two or more values
- Ordinary and non-negative weighted means
- Negative values and weights that do not total 100
- Sum, range and per-row weighted contributions
Not included
- Median, mode or outlier handling
- Missing-data or grading policies
- Probability or statistical-inference claims
What this means
An ordinary average gives every row equal influence. A weighted average multiplies each value by its weight and divides by the total weight.
Weights do not need to total 1 or 100; only their relative size matters. Zero-weight rows remain visible but contribute nothing.
Formula & worked example
average = sum of values ÷ number of values weighted average = sum(value × weight) ÷ sum(weights)
Values 10 and 20 with weights 1 and 3
- Weighted sum
- 10 × 1 + 20 × 3 = 70
- Total weight
- 4
The weighted average is 17.5.
How this calculation works
The calculation follows the formulas, definitions and assumptions explained on this page. The references below support the method and any stated boundaries.
Official sources
- NIST — arithmetic mean — Definition of the arithmetic mean as the sum of observations divided by their number
Common questions
Must weights add to 100?
No. The calculator divides by their actual total, so 1 and 3 produce the same average as 25 and 75.
Can values be negative?
Yes. Values may be negative; weights must be zero or positive.
What happens when all weights are zero?
A weighted average is undefined without positive total weight, so the calculator shows an error instead of inventing a result.