Identify each item’s value and its weight
Compute each weighted contribution: value × weight
Sum all weighted contributions
Compute the sum of all weights
Divide total weighted contributions by total weights: (Σ value × weight) / (Σ weight)
If weights are already in percentages, convert to decimals or use the same formula with percentage weights (result unchanged if all weights sum to 100)
If weights sum to 1, the denominator is 1, so the weighted average is Σ value × weight
For frequencies (e.g., exam scores), use: (Σ score × frequency) / (Σ frequency)