Matrix product. The number of columns in the first array must equal the number of rows in the second. Weighted scores, portfolio math, and transition models all reduce to it.

Syntax

=MMULT(array1, array2)

Example

=MMULT(A2:C4,E2:G4)

• 2 by 2 times 2 by 2

  =MMULT({1,2;3,4},{5,6;7,8}) → {19,22;43,50}

  Rows of the first times columns of the second.

• Dot product

  =MMULT({1,2,3},{4;5;6}) → 32

  A row times a column is a single number: 4 + 10 + 18.

• Weighted score

  =MMULT(B2:D2,F2:F4) → 81

  Weights 0.5, 0.3, 0.2 in a row times scores 80, 90, 70 in a column.

• The result spills. Columns in array1 must equal rows in array2.
• A row of weights times a column of values is the same as SUMPRODUCT, but MMULT scales to many rows at once.
• Portfolio variance: MMULT(MMULT(w,Cov),TRANSPOSE(w)).
• In older Excel confirm with Ctrl+Shift+Enter over the right-sized output range.

• #VALUE! when the inner dimensions do not match or a cell is blank or text.
• Results spill; anything in the way causes #SPILL!.