About the Weighted Average Calculator
A weighted average gives some values more influence than others. Type one value and its weight on each line, and the calculator multiplies each value by its weight, adds the results and divides by the total weight. It works for course grades where the final exam counts for more than homework, for average purchase prices when you bought different amounts, and for survey scores with different group sizes. Weights can be percentages or any numbers, such as credit hours or units bought. A second panel works out the average you still need on the remaining weight to reach a target.
Updated October 2026
How to use the Weighted Average Calculator
- 1Type one pair per line: the value, then its weight, like 90 40.
- 2Use percentages, credits, quantities or any positive numbers as weights.
- 3Read the weighted average and compare it with the plain average shown under it.
- 4To plan ahead, open the target panel and enter the average you want and the weight still to come.
- 5Press Copy result to keep the answer.
When a plain average misleads
A plain average is only fair when every item matters equally. School and work rarely work that way. A semester might count homework as 20 percent, midterms as 30 percent and the final as 50 percent. Averaging your three scores without weights gives the quiz the same say as the final, which is not how your grade is calculated. The weighted average follows the real rules.
Common uses
- Course grades where categories have different percentages
- Grade point averages where each course has different credit hours
- Average cost of shares or stock bought at different prices
- Average price per unit across several orders
- Survey results when groups have different numbers of people
Planning the score you need
The target panel answers the question students ask most often: what do I need on the final? Enter what you have so far, the overall average you are aiming for and the weight left. If the number you need is above the maximum possible score, the target is out of reach and you may want to aim a little lower. It treats scores and the target on the same scale, so keep them all out of 100 or all out of 4.
Tips for accurate results
Write each pair on its own line and keep the order value first, weight second. Do not mix percentages and raw credits in one list. For grade points, use the Grade Calculator or the GPA Calculator when you want letter grades handled for you, and the Average Calculator when every item counts equally. For spread rather than centre, try the Standard Deviation Calculator. The Percentage Calculator helps when you need to turn a weight into a share of the total.
Features
- One value and weight per line, separated by a space, comma, semicolon or tab
- Weights as percentages (30%) or plain numbers
- Shows the plain average next to the weighted one
- Needed-score panel for a target average
- Clear error messages that name the bad line
- Works for grades, credits, prices and survey data
- Runs in your browser
Frequently asked questions
How do I calculate a weighted average?
Multiply each value by its weight, add up those products, then divide by the sum of the weights. If you scored 90 on something worth 40 and 70 on something worth 60, the answer is (90×40 + 70×60) ÷ 100 = 78. Enter the pairs and the calculator does the steps for you.
Do the weights have to add up to 100?
No. The calculator divides by whatever the weights add up to, so percentages that total 100, credit hours, or quantities all work. Only the ratio between weights matters, which means 2 and 3 give the same result as 40 and 60.
What is the difference between a weighted and a simple average?
A simple average treats every value equally. A weighted average lets bigger items count for more. If a final exam is worth 50 percent and a quiz 5 percent, a plain average would overstate the quiz. The tool shows both so you can see the gap.
How do I find what I need on my final exam?
Enter the scores you already have with their weights, then open the target panel. Type the overall average you want and the weight of the exam that remains. The calculator shows the average you need on that remaining part, which can be above 100 if the target is out of reach.
Can I use it for average price or cost?
Yes. Put the price in the value column and the quantity in the weight column. Buying 10 items at 5 and 30 items at 4 gives a weighted average price of 4.25 per item. This is how an average purchase cost is worked out.
Can a weight be zero or negative?
A weight of zero is allowed and simply ignores that line. Negative weights are rejected because they have no sensible meaning for a normal average. If every weight is zero there is nothing to divide by, so the tool asks for at least one positive weight.