IF Function - too many arguments

Dear all,

I am trying to do some tiered pricing model and I have created the following formula:

Formula:

=IF(D2<=$C$12,D2*$D$12,IF(D2<=$C$13,($C$12*$D$12)+((D2-$C$12)*$D$13),IF(D2<=$C$14,(($C$12*$D$12)+(($C$13-$C$12)*$D$13)+((D2-$C$13)*$D$14)),IF($D$2<=$C$15,(($C$12*$D$12)+(($C$13-$C$12)*$D$13)+(($C$14-$C$13)*$D$14)+(($D$2-$C$14)*$D$15))),(($C$12*$D$12)+(($C$13-$C$12)*$D$13)+(($C$14-$C$13)*$D$14)+(($C$15-$C$14)-$D$15)+(($D$2-$C$15)*$D$16)))))

I am sure this is correct but when I press enter it says too many arguments. Is there a simpler way of doing this?

Many thanks in advance. I have also uploaded a trial spreadsheet.

Alex

Try this ...

=SUMPRODUCT((D2>=C3:C7)*(D2-C3:C7)*(D4:D8-D3:D7))

Amazing! and so simple!! Thank you so much!