Calculate weighted averages with customizable weights for grades, investment returns, inventory costs, or any data set.
This calculator takes a list of value-weight pairs, multiplies each value by its own weight, adds the products, and divides that sum by the total of all weights. It's the standard weighted arithmetic mean. The most common surprise: weights don't have to add up to 100 or 1. A quantity, a point total, or a headcount works fine as a weight, since the tool normalizes by dividing by whatever the weights actually sum to, not by an assumed total.
A concrete input and expected output from the current implementation.
Input
Value 90, Weight 20 Value 85, Weight 30 Value 78, Weight 50
Expected output
82.5
(90x20 + 85x30 + 78x50) / (20+30+50) = (1800+2550+3900)/100 = 8250/100 = 82.5.
Each row holds one value and one weight. The tool multiplies value by weight to get a product, sums all products, then divides by the sum of the weights entered. This is done as soon as a row is added or edited, so the running result updates without a separate submit step.
Because the division uses the actual total of the weights you entered rather than a fixed denominator, weights can be percentages, points, dollars, units, or any positive numbers on any scale. Two rows weighted 3 and 7 produce the same average as rows weighted 30 and 70.
No. The calculator divides by whatever your weights actually sum to, so entering point values, quantities, or dollar amounts as weights works without converting them to percentages first.
The tool will compute an answer, but negative weights don't correspond to a real weighting scheme in the standard weighted-mean formula, and the result can behave unpredictably: depending on the other values and weights, it may land inside or outside the range of your entered values, and if the weights happen to sum to zero the calculation is undefined (division by zero). Treat a negative weight as an edge case worth double-checking rather than a normal input.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Calculate percentages, percentage change, and what percent one number is of another with step-by-step breakdowns.
Calculate tips and split bills between multiple people with customizable tip percentages and rounding options.
Calculate monthly payments, total interest, and generate amortization schedules for loans and mortgages.
Calculate Body Mass Index from height and weight with category classification and healthy range guidance.
Calculate sale prices, savings amounts, and final costs after single or stacked percentage discounts.
Compute mean, median, mode, standard deviation, variance, and other descriptive statistics from a data set.