How to calculate a weighted average
✓ Verified in LibreOffice 25.8.7.3Average values where each one counts for a different weight.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =SUMPRODUCT(A2:A4,B2:B4)/SUM(B2:B4) | SUMPRODUCT multiplies each value by its weight and totals; divide by total weight. |
| Google Sheets | =SUMPRODUCT(A2:A4,B2:B4)/SUM(B2:B4) | Identical. |
| LibreOffice Calc | =SUMPRODUCT(A2:A4,B2:B4)/SUM(B2:B4) | Identical. |
How it works
SUMPRODUCT(values, weights) computes 90*2 + 80*3 + 70*5 = 770, and SUM(weights) = 10. Dividing gives a weighted average of 77 - lower than the plain average because the 70 carries the most weight.
Verified, not just documented
We ran =SUMPRODUCT(A2:A4,B2:B4)/SUM(B2:B4) in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 77 — exactly the expected result. Every formula here is confirmed by actually executing it.