Much like us humans, dogs vary in size, metabolism and weight. This is why there is no specific 'healthy weight' guide to apply to all dogs. You can find the average weight of certain breeds online however, remember this is just the average and the above applies.
As dogs come in all shapes and sizes, this guide may not be as straightforward for your breed. For example, whippets and greyhounds are lean and athletic whilst bulldogs are much broader. Dogs with much fluffier coats will be harder to negotiate the fur!