Do the weights have to add up to 100%?
No. The calculator automatically sums the weights and divides by that total. You can use raw percentages (summing to 100), course credit hours (e.g. 3, 4, 1), or dollar amounts.
What happens if all weights are equal?
If all weights are equal, the weighted average is mathematically identical to the simple arithmetic average.
How do teachers use weighted averages for gradebooks?
Teachers assign percentage categories (e.g. Exams 50%, Homework 30%, Participation 20%) to ensure rigorous exams influence the final mark more than casual assignments.
Can weights be negative or decimal numbers?
Weights can be positive decimal numbers. While negative weights exist in complex financial hedging, practical educational and business weights must be non-negative.
What happens if I enter more values than weights?
Every value requires an accompanying weight. If counts do not match, the calculator notifies you to balance the inputs.
How accurate is the result?
Results use JavaScript's 64-bit floating point — accurate to 15+ significant digits for most calculations.
Can I enter decimal numbers?
Yes, decimals are fully supported.
Is it free?
Yes, completely free.
Does it show the formula?
Yes, the formula is displayed on the page.
Can I use it on mobile?
Yes, the calculator is fully responsive.
Does it save my inputs?
No data is stored — all calculations are done locally in your browser.
What if I get an error?
Check for invalid inputs such as division by zero or negative square roots.