Neutralize those units!!!

It is possible this tip has been blogged before, but it’s worth refreshing just in case. Sometimes there will be situations when creating parameters in your Revit families, when you would like to multiply one parameter by another parameter to get a result. So in this simple example we have two parameters A_length and B_length and we would like to multiply these together to get a resulting new "length". Both parameters have been setup as “length” parameters.

The natural thing to do would be to create a new calculated “length” parameter and setup the formula as

A_length * B_length

However, if you do this in Revit you get this!!!! Ouch

What do you mean inconsistent units!!!! I…… don’t bbbbbbbelieve it!! So you swear at Revit and you wonder what your next move should be.

Well you actually have to neutralize the units in one of the parameters to get the result. Revit seems to be rather fussy about multiply two parameter of the same type together. It’s not like Excel. So if you divide one of the parameters by 1, this neutralizes the units and allows the calculated formula to perform correctly.

A_length / 1 * B_length

It’s a similar process if you have two “number” parameters and you want to multiply these together to get a resulting “length” parameter. So we have two parameters X and Y setup as “number” parameters. We’d like to multiply these together to get the result as a new “length” parameter.

Again, we get the same inconsistent units message if we just try to multiply these together.

However, this time if we multiply one of the parameters by 1 to reinstate the units, the calculated formula will now work.

A_length * 1 * B_length