How to use the weighted average calculator
Enter a value and its weight in each row — the weight can be a percentage, credit hours, quantity, or any number representing relative importance. Add as many rows as you need with Add Row. Your weighted average appears instantly, along with a contribution bar showing exactly how much each row is pulling the result.
Tap Go advanced to solve the formula backwards: pick which row is unknown, enter the weighted average you're targeting, and the calculator tells you the exact value that row needs.
The formula
Multiply each value by its weight, add up all those products, then divide by the sum of the weights. If every weight is equal, this collapses to the ordinary (simple) average — weighting only matters when some entries count more than others.
Worked example
Three exams worth different shares of a grade: 75 (worth 25%), 90 (worth 25%), and 88 (worth 50%):
The simple average of the same three scores is (75 + 90 + 88) / 3 = 84.33 — close, but not identical, because the 50%-weighted score of 88 pulls the weighted result up slightly more than an equal-weight average would.
What to use as a weight
A weight can be anything that represents relative importance or size: a percentage of a grade, course credit hours, quantity purchased, a sample size, or a time period. The weights don't need to add up to 100 or any particular total — proportional weights like 2 and 1 produce the exact same result as 67% and 33%, because the calculator always divides by the sum of whatever weights you enter.
Weighted vs. simple average
A simple average treats every number equally. A weighted average lets some numbers count more than others. The two only differ when weights are unequal — if every row has the same weight, the weighted average and the simple average are identical, which is exactly what the comparison line under your result shows.
Related tools
If you're averaging letter grades and credit hours specifically, the GPA Calculator handles the grade-to-point conversion for you. Need to know what score you need on a final exam to hit a target course grade? Try the Final Grade Calculator — it uses the same reverse-solve idea as this calculator's Go advanced mode.
Common questions
How do you calculate a weighted average?
Multiply each value by its weight, add up all those products, then divide by the sum of the weights: (w1x1 + w2x2 + ... + wnxn) / (w1 + w2 + ... + wn). This calculator does that automatically as you type.
What is the difference between a weighted average and a regular average?
A regular (simple) average treats every value equally. A weighted average lets some values count more than others by multiplying each by a weight before averaging — useful whenever items have different importance, size, or credit hours, like exam scores worth different percentages of a grade.
What should I use as the weight?
Anything that represents relative importance or size: a percentage of a grade, credit hours, quantity purchased, time period, or sample size. The actual numbers don't need to add up to 100 or any specific total — the calculator divides by their sum automatically, so proportional weights (like 2 and 1) work exactly the same as percentages (67% and 33%).
Can I calculate a weighted average with more than 3 values?
Yes — use the Add Row button to add as many value and weight pairs as you need. There's no limit.
How do I find the value I need to hit a target weighted average?
Enter all your known values and weights, then tap Go advanced, choose which row is the unknown, and enter your target weighted average. The calculator solves for the exact value that row needs, given its weight.