What is the size of a woodpecker egg?

Answering this question is harder than it seems! There do not seem to be very many sources that give descriptions of the eggs themselves; most tend to focus on the actual bird. I can tell you that the Pileated Woodpecker and the Northern Flicker have the two largest sized eggs of any of the North American woodpeckers while the the Downy Woodpecker probably has some of the smallest eggs. Varying species of woodpecker and their respective egg sizes are listed below.

Pileated Woodpecker: 33.16 x 25.21 mm

Red-Bellied Woodpecker: 25.06 x 18.78 mm

Red-Headed Woodpecker: 25.14 x 19.17 mm

Yellow-Bellied Sapsucker: 22.44 x 16.92 mm

Hairy Woodpecker: 23.81 x 18.04 mm

Red-Cockaded Woodpecker: 24.04 x 17.86 mm

Black-Backed Three-Toed Woodpecker: 21.32 x 18.94 mm

Northern Three-Toed Woodpecker: 23.32 x 18.01 mm

Downy Woodpecker: 19.35 x 15.05 mm