hatch rate calculations

How do people calculate their hatch rates?

Percentage of eggs hatching from what originally started? Or percentage of eggs hatching that make it to lockdown?

Just curious

Fuzzy, I do both using these formulas:

Fertility (%) = (Fertile eggs/eggs set) x 100%
Hatchability (%) = (Good chicks hatched/fertile eggs) x 100%
Total eggs hatched (%) = (Good chicks hatched/eggs set) x 100%

and the chart from page 11 of this pdf:

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And if you are a seller of hatching eggs they always have 99% hatchrate! Even if they only hached 8 eggs?

Smiling, I don't even both with hatchability percentages. I just hatch. sometimes I have a good hatch, like 85% of the eggs set (yep, total number), sometimes I get anywhere from 40 to 85%. Never ever once have had a hatch that was above 85%, and I certainly would never expect it. I hear of people that say they get 98% hatchrate, and I think good on them, something must be near perfect with what they are doing. Not me. Nothing near perfect here. Just hatch a whack of chicks each year and feel pretty good if I have a 50% hatch out of chicks. It really doesn't matter what my hatchability rate number is, I just hatch, don't care about statistics much.

That pdf file that FlickerChick put in here is a good one and has some very valuable advice about hatching. I read it before somewhere and have it already bookmarked, but was nice to re-read. I like the part where it said that if a chick is over 1 day late in hatching, to discard, it is a weak chick, that is why the non-emergence from the confines of its shell, and not to help it out. I am that way. Tough love. Gotta get out within 2 days or....don't want any weakness in the critters around here, and that starts during the birthing process. Blah, off topic, apology, ramblin'. Have a wonderful day, CynthiaM.

I like the way Flicker puts it.
When I say % hatchability I always do eggs hatched/fertile eggsX100%
You can't include the non fertiles in your hatchability percentage because they were never destined to hatch. But you also can't wait till day 18 (lockdown) do to your infertiles because some that have started and died along the way may be hard to tell from infertiles at that point. I always do 7 days candling for infertiles, if any have started and stopped before 7 days they are still included in my hatchability %.

I look in bator. If most of the eggs I put in produced chicks = good hatch rate.

If not = bad hatch rate.

It's very technical.

^ Haha, that works too. Chicken math is the only kind of math I like.

Culling unthrifty/or slow to hatch chicks is probably a good idea when thinking about the long term health of your flock, but I do have trouble following through with it. I especially hate watching chicks struggling to hatch, wondering if it’s something I did or didn’t do. Tough love is HARD.

Thank you,

That all makes sense. I kinda like cynthia and uno's approach