2010 Specialized Tricross BB size
The typical thing to do here would be pull the cranks and measure the spindle length with a caliper. You don't need to pull the BB itself, all you care about is the spindle length. (On older bikes you'd also care about whether it was symmetrical or not, but yours will be).

There are some tricks you can play if that is not an option.

If the spindle is hollow, you can remove the crank bolts and poke a wire, spoke, QR, or string all the way through, mark it, pull it out, and know your spindle length that way.

If it's not hollow, you can remove the crank bolts and then use a caliper or pocket ruler to measure the distance between the tip of the spindle and the outside surface of the crank. Then you could use a couple straight-legged chairs or similar pieces of furniture, or some big squares, pushed up against the surfaces of the crank on either side of the bike to measure the spindle. Sandwich the bike between them, gently lift it up, measure the distance between the two surfaces, subtract the inset distance of the spindle tip, and that's your spindle length.