Weighted Average Calculator Formula

Understand the math behind the weighted average calculator. Each variable explained with a worked example.

Use the Weighted Average Calculator

Formulas Used

Weighted Average

weighted_avg = weighted_sum / (total_weight / 100)

Total Weight

weight_check = total_weight

Should equal 100%

Simple Average (comparison)

simple_avg = (score1 + score2 + score3 + score4) / 4

Variables

VariableDescriptionDefault
score1Category 1 Score(%)90
weight1Category 1 Weight(%)20
score2Category 2 Score(%)85
weight2Category 2 Weight(%)30
score3Category 3 Score(%)78
weight3Category 3 Weight(%)30
score4Category 4 Score(%)95
weight4Category 4 Weight(%)20
total_weightDerived value= weight1 + weight2 + weight3 + weight4calculated
weighted_sumDerived value= score1 * weight1 / 100 + score2 * weight2 / 100 + score3 * weight3 / 100 + score4 * weight4 / 100calculated

How It Works

How to Calculate a Weighted Average

Formula

Weighted Average = Sum of (Score x Weight) / Sum of Weights

Weights should add up to 100%. Higher-weighted categories have more impact on your final grade.

Worked Example

Homework (90%, 20%), Midterms (85%, 30%), Final (78%, 30%), Participation (95%, 20%).

score1 = 90weight1 = 20score2 = 85weight2 = 30score3 = 78weight3 = 30score4 = 95weight4 = 20
  1. 01Homework: 90 x 0.20 = 18.0
  2. 02Midterms: 85 x 0.30 = 25.5
  3. 03Final: 78 x 0.30 = 23.4
  4. 04Participation: 95 x 0.20 = 19.0
  5. 05Total: 85.9 / 1.00 = 85.9%

Ready to run the numbers?

Open Weighted Average Calculator