How to weigh eggs and calculate weight loss

Weigh egg trayWeighing
your eggs is the best way to make sure you’ve got
humidity inside
your incubator

right.  I figured some of you might find the idea
daunting, so I’ll take you through it step by step.

First, you want to find
the weight of your eggs at the time you put
them in the incubator.  There’s no need to weigh one egg at a time
— just put all of the eggs on a scales at once.  If you’re lucky
and your tray of eggs can be lifted straight out of the incubator (like
in our new
Octagon 20
), you can
put the tray and eggs on the
scales together.  Then take the eggs out of the tray and weigh the
tray alone.  The weight of the eggs without the tray can be
calculated using the following simple formula:

weight of eggs) = (Weight of eggs and tray) – (Weight of tray)

Our eggs and tray
weighed 59.8 ounces at the beginning of our
incubation period and the tray alone weighed 7.3 ounces, so the eggs

weight of eggs) = 59.8 – 7.3

(Current weight of eggs) = 52.5

The next step is to
figure out how much I want the eggs to weigh at the
end of the incubation period.  We’re aiming for a 13% weight loss,

weight at end of incubation) = (First day weight of eggs) X 0.87

For our eggs, that is:

weight at end of incubation) = 52.5 X 0.87

(Goal weight at end of incubation) = 45.7

It’s also useful to know
what our daily weight loss goal is:

goal weight loss) = (First
day weight of eggs) – (Goal weight at end of incubation)


Our eggs need to lose:

goal weight loss) = 52.5 –


(Daily goal weight loss) = 0.324

(For those of you who
ran away from algebra, be sure to do the subtraction before the
division in the equation above.)

Now I’m ready to find
out if my eggs are on track with their goal
weight loss on a certain day.  After two full days of incubation,
I weighed my eggs and tray again, subtracted out the weight of the
tray, and got a new weight of 51.8 ounces.  Did I have the
humidity set right?

First, I calculate the
goal weight loss for the day:

weight loss on a certain day) = (Daily goal weight loss) X (Days since
incubation started)

For my eggs:

weight loss on day 2) = 0.324 X 2

(Goal weight loss on day 2) = 0.648

Next, I figure how much
the eggs should weigh now:

(Goal weight on a certain day) = (First day weight of eggs) –
(Goal weight loss on a certain day)

For my eggs:

weight on day 2) = 52.5 – 0.648

(Goal weight on day 2) = 51.85

Weighing eggs to check humidityIf
you remember, my eggs weighed 51.8 ounces on day 2, so if anything
they’ve lost just a hair too much weight.  I had let the
incubator’s percent humidity drop down into the high 30s that morning
since it ran in the low 50s the first day, but it looks like I need to
refill the well or close the vent.

I hope this math doesn’t
look daunting!  I promise, it’s simple
arithmetic, and weighing your eggs every two or three days during
incubation should increase your hatch rates.

Our chicken waterer never spills or fills with

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