A post on SED asked for a formula to calculate the available DC output current
from a bridge rectifier given the transformer AC current rating.

The attachment shows the derivation of a formula.

In real circuits, you will get a higher DC output current than this formula
predicts due to clipping of the grid waveform and due to leakage inductance.

A formula covering those cases would be too complicated for practical use, but
the formula ignoring those effects, given in the attachment, is a good starting
point.

This .gif file can be viewed conveniently in Firefox. Place the cursor over the
image and right click to magnify.