Want to open up a bearing wall clear span of 25 ft what size wood beam do I need

Something that span should be engineered. What is the load? LVL beams would be the best choice and you can't make them yourself. What is the roof structure? Stick built?

If you want to create a 25 foot clear span on a load bearing wall then you are going to need a structural engineer to tell you what is required, although I am afraid you will be putting in a steel beam for a span that long. Have you considered putting in a column or two to make the span more manageable (and greatly reduce your cost)?

I should add that the load bearing wall distributes the load evenly across its length. If you cut openings in the wall you will be redistributing the load, and will need to add substantially to the footings to support the new load points if you go with a 25 foot clear span. Installing columns reduces the span and requires much smaller footings.

--(In)Specter1
ICC MCP