[pandora]

Really quickly - what's the humidity again? I'm sure I used 40% last year, up to 50% for the last 3 days. Anyone want to tell me I'm right or wrong?

[min200]

I run at 45% and then 50-60% for the last 3 days.  Someone will be along shortly to disagree 

[AL Hathaway]

Humidity—The moisture level in the incubator should be about 50 to 55 percent relative humidity, with an increase to about 65 percent for the last 3 days of incubation.

[Casey76]

50-55% humidity for the first 18 days is really too high for chicken eggs.  The eggs won't lose enough weight (water), the air sac won't grow, and the chicks can drown in their shells.

A lot of people use 35 - 45% RH for the first 18 days, then increase to 60-65% during the last three days