How many days between chicks hatching?

[HennyPenny44]

Not sure if this has been answered before. I had 6 in the incubator and 6 under broody mama, all chicken eggs and all set at the same time. The incubator chicks hatched on days 19 and 20 (4 of them). Mama hatched 4 also on those days and then abandoned her nest so I put the last 2 in the incubator. It’s day 21 and no movement. One of the incubator eggs was moving and peeping earlier today but it’s silent and still tonight. Being that all my chicks hatched on day 19 and 20, is there a chance the others can even hatch on day 23 or 24 or even later? Not sure if I committed a no no but I candled them today to check for movement but saw none that I could discern.

 

[BirdsBeesTrees]

Candling them is fine.
Do you have calibrated thermometers in your incubator? You incubator could be running a bit cooler and that could delay the hatch.
If you aren't seeing movement like a faint fluttering around the air cell though that could be bad news.

 

[HennyPenny44]

Candling them is fine.
Do you have calibrated thermometers in your incubator? You incubator could be running a bit cooler and that could delay the hatch.
If you aren't seeing movement like a faint fluttering around the air cell though that could be bad news.

The incubator states the temp. and humidity were calibrated before shipping out and I don’t have an extra thermometer. It’s set to 99.5. But I don’t think my temp. is too low or my first wouldn’t hatch so early. This is my first time hatching eggs and candling them but I don’t see any movement. All 4 are dark inside. One has a very large air cell and another has a saddle shaped one. These are shipped eggs and 8 out of 12 hatched so I’m happy about that but sad for the ones that didn’t make it.