transformer voltages are rated in volts RMS, not peak. the DC voltage will depend on the type of rectifier, and for a bridge rectifier it will be 1.414 times the RMS voltage. transformer voltage ratings are not used as marketing tools, as the specs have long been standardized, and the transformers are rated in engineering terminology, not consumer terminology. if a transformer doesn't meet published specs, it doesn't sell, unlike consumer audio, which can have a listed power output of the amplifier wattage multiplied by the square of the marketing executive's shoe size.