Count unique if criteria is met

Try this formula

=SUMPRODUCT(($A$2:$A$15=D2)/COUNTIF($B$2:$B$15,$B$2:$B$15&""))

Row\Col	A	B	C	D	E
2	Joanna	ECO60610		Joanna	1
3	Joanna	ECO60610		Ilona	3
4	Joanna	ECO60610		Sylwia	1
5	Ilona	ECO56003		Marta	1
6	Sylwia	ECO59237
7	Sylwia	ECO59237
8	Sylwia	ECO59237
9	Sylwia	ECO59237
10	Sylwia	ECO59237
11	Sylwia	ECO59237
12	Marta	ECO59824
13	Marta	ECO59824
14	Ilona	ECO60593
15	Ilona	ECO59298

Originally Posted by AlKey

Try this formula

=SUMPRODUCT(($A$2:$A$15=D2)/COUNTIF($B$2:$B$15,$B$2:$B$15&""))

Try that formula on this data:

Data Range

	A	B
1	------	------
2	Joanna	ECO60610
3	Joanna	ECO60610
4	Joanna	ECO59237
5	Ilona	ECO56003
6	Sylwia	ECO59237
7	Sylwia	ECO59237
8	Sylwia	ECO59237
9	Sylwia	ECO59237
10	Sylwia	ECO59237
11	Sylwia	ECO59237
12	Marta	ECO59824
13	Marta	ECO59824
14	Ilona	ECO60593
15	Ilona	ECO59298

Just some FYI...

The SUM(IF(FREQUENCY array version is more efficient (faster to calculate) especially on large data sets.