One way:

In O21:
=IF(AND(I21="IO",L21<"",N21<""),L21*N21,IF(AND(I 21="PI",L21<""),PMT(0.09/12,30*12,-L21),""))

Works? High-five it here then, click YES below
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xdemechanik
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"Scoober" wrote:
Hi - I am working on a mortgage spreadsheet.

I need the spreadsheet to work out interest only calculations, principle &
interest calculations, and remain empty if no loan amount or interest rate is
entered.

I currently use this formula that preforms step 1 and step 3 perfectly

O21: =IF(OR(L21="",N21=""),"",L21*N21)

Cell definition is L21 = loan amount, N21 = Interest rate

The cell that will have either IO (Interest Only) or PI (principle and
Interest) is I21.

The principle and interest formula I want to use (I know it's crude, but
does the job required) is =PMT(0.09/12,30*12,-L21)

To sum up:

When IO is placed in I21 I require the 'interest only' formula to work, when
PI is place in I21 I require the 'Principle and Interest' formula to work,
and if nothing is placed in L21 or N21 when nothing is placed in O21.