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Egg hatching calculator

Set the date your eggs went in. We lay out all 21 days: when to turn, candle, lock down and welcome the chicks.

Your eggs

99.5–100°Fforced-air incubator
50–60%humidity days 1–18
65–75%humidity at lockdown
3+a dayturns, odd number

Store eggs for hatching cool (55–60 °F) and set them within about 7 days of laying. Other birds use the chicken steps scaled to their days.

Hatch day

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    The rules behind the numbers

    21 daysDays to hatch (chicken)Mississippi State University Extension · Virginia Cooperative Extension · University of Maine Cooperative Extension +1 more
    99.5–100 °FForced-air incubator temperatureMississippi State University Extension · Virginia Cooperative Extension · University of Maine Cooperative Extension +2 more
    101–102 °FStill-air temperature (top of the eggs)Mississippi State University Extension · Virginia Cooperative Extension · University of Maine Cooperative Extension
    50–60 %RHHumidity, days 1–18Older extension sheets say 55–65%, Illinois 50–55%, and the incubator maker Brinsea 45–50%.Mississippi State University Extension · Virginia Cooperative Extension · University of Maine Cooperative Extension +3 more
    65–75 %RHHumidity from lockdownMississippi State University Extension · Virginia Cooperative Extension · University of Maine Cooperative Extension +2 more
    6–12 h after hatchMove chicks to the brooderVirginia Cooperative Extension · University of Maine Cooperative Extension · Utah State University Extension +1 more

    Questions

    How long does it take for a chicken egg to hatch?

    21 days in an incubator or under a hen. Turning stops on day 18 (lockdown) and most chicks hatch on day 21, often within 24 hours of each other.

    What temperature should an incubator be?

    99.5–100 °F in a forced-air (fan) incubator, or 101–102 °F measured at the top of the eggs in a still-air incubator.

    What humidity do eggs need?

    About 50–60% relative humidity for days 1–18, then 65–75% from lockdown to hatch. Sources differ: some incubator makers suggest 45–50% for the first 18 days.

    When should I candle eggs?

    On days 7, 14, 18. On day 7 look for spreading veins (developing), a clear egg (infertile) or a blood ring (stopped early, remove it).

    When do I take chicks out of the incubator?

    When they are dry and fluffy, about 6–12 hours after hatching. Chicks live on the absorbed yolk for that time, so there is no rush, and opening the incubator early drops the humidity for eggs still hatching.

    Sources

    1. 1Care and Incubation of Hatching EggsMississippi State University Extension (T. W. Smith Jr.; PDF dated 2009)
    2. 2Incubating Eggs (2902-1090)Virginia Cooperative Extension (P. Clauer; 2009)
    3. 3Maine Poultry Facts: Hatching Your Own Chicks (Bulletin #2072)University of Maine Cooperative Extension (Hawes; updated Coffin; 2009, 2020)
    4. 4Hatching and Caring for ChicksUtah State University Extension (Farnsworth, Hadfield, Longmore; March 2025)
    5. 5Incubation and Embryology Q & AUniversity of Illinois Extension
    6. 6Mastering Incubator Humidity: Why Egg Weight Loss is KeyBrinsea (incubator manufacturer)
    7. 7The Avian Embryo (P1150)Mississippi State University Extension (T. W. Smith Jr.; reviewed J. Wells)

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