How big are mallard or rouen duck eggs suposed to be?
I hаνе a duck I rесkοn ѕhе′s a mallard, bυt ѕhе mау bе a rouen bесаυѕе ѕhе іѕ hυgе, bυt thаt сουld bе јυѕt bесаυѕе wе feed hеr well. 
Anyways, hеr eggs аrе nοt fertilized bυt thеу аrе аbουt thе same size аѕ chicken eggs-іѕ thаt normal?
there as huge as chicken eggs
They are usually slightly larger than a Chicken egg,so yours are O.K.
Yep, ours were a small bit larger than a chicken egg. You know, duck eggs are splendid for baking. A lot of people like making cakes with them. The yolk of course is pretty huge and more rich. So if they aren’t fertile, you could still place them to use
If she is a mallard, her eggs will have a green tint to them, and they are edible, and excellent for baking, like the other dude said. They should be about the same size as a large chicken egg. The mallards I kept were leaflets, I had as much as 78 one time, now none. I miss them, and miss seeing them glide nearly my farm !!!
Well how huge is she? If she is lighter than the opther ducks you may or may not have than its a mallard. If there are heavy like pekin ducks than its a rouen duck. Both look similar.
Also mallards glide rouen do not. You can find out by chasing after if they glide in the air there mallards. Not then rouens.
If this is the first time that she had layed eggs this is completly normal especailly for a mallard duck. But also it being the first eggs in a month layed it will be small.
Excellent Luck!