[WhatEverYouWant]

The short answer is you don't calculate the beam size; you hire a structural engineer to calculate it.

The longer answer is that there are too many loads that have to be considered that change based on your location, room size, roof configuration, roof loading, floor loading, etc. There's also the posts/jack studs supporting the beam ends, and foundation support for them, to figure out. The load that was distributed across that 10', will now be concentrated at the ends of the beam, so the foundation has to be able to support those concentrated loads and spread it over a large enough area of the soil under the foundation.

I know that I need roughly a 11.5" to 14" LVL depending on if it's 3-ply or 4-ply and the jack posts will be sitting on the concrete footings and the roof is supported by the outer walls. I have to get a structural engineer to sign off on this when I'm ready to go, but I just wanted to figure out the costs and decide if I was going to do it before I hired one.

 

[WhatEverYouWant]

To many loads to be determined. What is going to hold this beam? What is going to support that post that holds the beam?

concrete footings and that was one of the things I was trying to decide a couple of 6 x 6 posts or steel jack posts

 

[WhatEverYouWant]

If you say so. I'm curious, how do you know that?

Because I sent all the require information to a place that makes and sells LVL's and they told me it would 3-ply at 14" and if I wanted to do 4-ply at 11.5" I'd have to get a structural engineer. But again didn't want to waste money on one and then find out after it was more then I was looking to spend.

 

[WhatEverYouWant]

Rod is right about the footing for a beam.
Your foundation and footing will look like this
View attachment 757778

And if the beam had been planned for it would be like this with a point load for the beam.
View attachment 757780

It's was planned for a beam, but at the time I was building it I decided to add an apartment and go with a wall instead to create 2 bedrooms. Now I don't want to rent anymore and decided to open up that part of the Basement.

best shot I have of the footings.

 

[WhatEverYouWant]

You don't have room for a 14" but suggestions from here or the manufacture may not get passed the city inspector.

Thanks I know I don't.

Plan was to try and figure out want may be possible before I hire a structural engineer to sign off just wanted to roughly figure out the costs and decide if I was going to do it before I hired one.