Egg Incubation Chart: Day-by-Day Hatching Timeline

Chicken eggs hatch in 21 days under proper incubation conditions. Bantam eggs often hatch a day or so early, around day 19 to 21. The clock starts when eggs reach full incubation temperature, not when you place them in the machine, so eggs set in the evening typically hatch the evening of day 21. Hatching a few hours to a day either side of the mark is normal, but a consistently early hatch suggests your incubator runs warm, and a late hatch suggests it runs cool.

Run a forced-air incubator (one with a fan) at 99.5 degrees Fahrenheit for the entire incubation. A still-air incubator should read about 101 to 102 degrees measured at the top of the eggs, since temperature stratifies without a fan. Keep humidity around 45 to 55 percent for days 1 through 17, then raise it to about 65 to 75 percent for lockdown, days 18 to 21. Verify both numbers with an independent thermometer and hygrometer, because built-in readouts are often off by enough to hurt a hatch.

Stop turning at the end of day 17 or the start of day 18, when lockdown begins. Before then, eggs should be turned an odd number of times per day, at least 3 and ideally 5 or more, or continuously by an automatic turner. Turning keeps the developing embryo from sticking to the shell membrane. After day 18 the chick is maneuvering into hatching position with its beak toward the air cell, and turning would interfere. If your eggs sit in an automatic turner, remove the turner rails at lockdown and lay the eggs on their sides.

Candle at day 7, day 14, and day 18, just before lockdown. At day 7 a fertile egg shows a spider web of veins with a dark embryo at the center, while a clear egg with no development was likely never fertile and can be removed. At day 14 you should see a large dark mass, movement, and a growing air cell. At day 18 confirm the air cell fills about a third of the egg and remove any quitters. Candle quickly in a dark room, handle eggs gently, and never candle during lockdown.

Avoid it. Every time you open the incubator during days 18 to 21 you dump the high humidity that keeps hatching membranes moist. If membranes dry out, they tighten around the chick, a problem keepers call shrink-wrapping, and the chick can become trapped. Set up lockdown properly, then keep the lid closed until the hatch is essentially finished. It is fine to briefly remove dry, fluffed chicks once most of the hatch is done, but do it fast and only when no other eggs have external pips actively progressing.

Almost never. Hatching takes many hours, commonly 12 to 24 from the first external pip, with long rests in between, and a chick that seems stuck is usually just resting and absorbing the last of its yolk and blood supply. Helping too early can rupture blood vessels in the membrane and cause fatal bleeding. Intervention is only worth considering when a chick has made no progress at all for a full day after pipping, the membrane looks dry and brown, and you proceed in tiny steps, stopping at any sign of blood.

Temperature is almost always the answer. An incubator running even half a degree warm speeds development and produces hatches at day 19 to 20, often with weaker chicks. Running cool slows development and pushes the hatch to day 22 or 23 with lower hatch rates. Consistently early or late hatches mean your incubator's true temperature differs from its display, so calibrate with a trusted independent thermometer. Old eggs, storage above 60 degrees before setting, and big room temperature swings also stretch or scatter hatch timing.