Average Percentage Calculator

Enter the values the average percentage form asks for and the result is computed here, in the page, with no sign-up and no upload. Change one field at a time to see how sensitive the average percentage figure is to that assumption.

Simple Average
Weighted Average

Enter Percentage Values

Enter Percentage Values with Weights

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Instant results No signup required Standard formulas Free to use

The formula, worked through

Simple: (x₁ + x₂) ÷ n · Weighted: Σ(wᵢ × xᵢ) ÷ Σwᵢ

x = percentage values · w = weights

  1. The simple average of 80% and 90% is (80 + 90) ÷ 2 = 85%.
  2. If those scores came from tests worth 30 and 70 points, the weighted average is (80×3 + 90×7) ÷ 10 = 87%.
  3. Weighting matters whenever the items cover different amounts of work.
  4. Use the simple mode for equal-size items and the weighted mode for grades, portfolios, or mixed samples.
Example
Scores
80% and 90%
Weights
3 and 7

Result 87% weighted · 85% simple

Frequently Asked Questions about Average Percentage Calculator

How do I sanity-check the average percentage result?

Rerun the calculator with a known example and compare it against the figure you expect; then swap back to your own numbers.

Which average percentage inputs change the outcome most?

Adjust one field at a time. The figure that shifts the result hardest is the assumption worth double-checking before you rely on it.

What is the average of 80% and 90%?

The simple average is 85%. With weights of 3 and 7 the weighted average rises to 87%.

When should I use a weighted average instead of a simple one?

Whenever the values represent different quantities — credit hours, portfolio positions, or sample sizes — because a simple mean treats a 1-credit lab the same as a 4-credit course.

What is the difference between simple average and weighted average of percentages?

A simple average adds all percentage values and divides by the count, treating every value equally. A weighted average multiplies each percentage by a specified weight (representing its importance), sums those products, then divides by the sum of the weights. Use weighted averages when some percentages should influence the final result more than others, such as a final exam counting more than a quiz.

How do I calculate the average of percentages with different weights?

You use the weighted average formula: (P₁×W₁ + P₂×W₂ + ... + Pₙ×Wₙ) ÷ (W₁ + W₂ + ... + Wₙ). For example, to average an 80% worth 40% weight and a 90% worth 60% weight, calculate (80×0.4 + 90×0.6) ÷ (0.4 + 0.6) = 86%. The heycalc.org tool automates this for any number of values and accepts weights that don’t sum to 1.