help please with toroidal transformers selection

[Tom J]

Are you asking for the dc after caps if so its about AC V x 1.4

...yes Clive DC after cups but the real reading tbh.
my 30V trafo has 32VAC and after bridge and 2x10.000uF reads 41.5VDC unloaded
calculation gives 32V*1.4=44.8V 3.3V more than real test.

[Clive S]

...yes Clive DC after cups but the real reading tbh.
my 30V trafo has 32VAC and after bridge and 2x10.000uF reads 41.5VDC unloaded
calculation gives 32V*1.4=44.8V 3.3V more than real test.

The rectifier will drop a bit of volts.

But remember the AC mains fluctuates all the time

[Doddy]

...yes Clive DC after cups but the real reading tbh.
my 30V trafo has 32VAC and after bridge and 2x10.000uF reads 41.5VDC unloaded
calculation gives 32V*1.4=44.8V 3.3V more than real test.

Your off-load DC voltage is largely irrelevant, other than to consider any maximum voltage for component selection. The RMS voltage (i.e. 32V) represents the effective average voltage under the specified rating of the transformer. The problem you will have with an unregulated supply is exactly that - it's unregulated and with large value smoothing capacitors you can expect that off full-load that the capacitors can hold up the DC level as the AC supply transits through the zero-crossing point, and the effective average DC voltage will increase above the full-load value (but below the peak value).

Expect to lose 1.2-1.6V (typically) across a bridge rectifier. This affects the peak DC voltage directly.

When looking for variance between your measured vs theoretical, as already mentioned in the replies - consider the actual AC line voltage at the time of test, and the ratio of the primary and secondary windings (many transformers are rated with primaries at 220VAC - if fed with 240VAC then expect the secondaries to read 240/220 x the rated voltage).k