Measure old windows,replace with new ones

[sty]

Hi Everyone. I know it`s been asked before.I did a search and came up with some info.
What is the proper way to measure for new construction windows?I am replacing six windows in my home with new construction windows. Two must fit into an opening that is recessed about the depth of a brick,then to the sill, and "touch" the soffit.I was told to measure the casement by removing the inside trim, then get measurements from outside to outside. The existing windows are a tight fit, I would like to order the new ones with brick mould and prevent any capping at all , unless If done with wood.(budget)
The other four are fitting over siding. Can I order a brick mould
on these as well and instead of peeling back the siding install so the brick mould gives a finished appearance , and prevents the window from having to fit between the siding?
Again , I am looking for a finished appearance to the outside,with no capping,if possible.
Thanks in advance for any and all replies.

Peter

[HayZee518]

I have included a diagram of what I can figure out you're doing

[sty]

Thanks Hayzee, good diagram. Yes , that is what I am doing , fitting into an existing opening , taking old windows out down to original framing (2x4`s)and re-installing new with brick mould. The 1/4" and 1/4" (total of 1/2") do need to be subtracted , as well as in my case I am ordering a standard brick mould, which is 1-3/8" (x2). So ,after calling the window store I was told to measure the opening from the outside, (ie50" width 50" high, subtract 3 1/4" to allow for brick mould , and shimming. So the size of window I would order is 46 3/4" wide ,by 46 3/4 wide . With the brick mould added on by the manufacturer , I end up with my 1/2" allowed for shimming , insulating and caulking.
Replacement windows fitting into the old frame need to be measured inside to inside , in which case capping would be required.
Talk about tricky! I would recommend (not that I`m a pro , just a handyman)anyone getting windows for self-installation to really take their time , check the measurements , and if possible , get someone who is knowledgeable in this area to take the measurements for you and pay if necessary.Once you buy your custom windows , they are non-returnable , and it would be quite a surprise to have a gaping hole in the wall with a nice window that is too big for the opening.
Thanks again, Take care!
Peter