Monday, December 21, 2015

Babies eat a lot and baby formula is expensive. How much have we spent so far on baby formula?

One important thing to note about the graph above is that 'ounces' here refer to the weight of the dry formula (i.e., before you mix it in a bottle). To estimate how much this costs, we just take the amount we pay per dry ounce (~$0.60) and multiply by the number of dry ounces used to get the following:

Note that this cost will obviously be higher if you use a more expensive formula (near us, the price range is $0.50 to $1.00 per ounce).

Another common way to measure this is to use the number of fluid ounces this corresponds to when mixed in a bottle. Generally, you use approximately 9 grams of formula per two fluid ounces. Since one dry ounce is approximately 28.35 grams, you get (28.35 grams/dry ounce)*(2 fluid ounces/9 grams) =  ~6.3 fluid ounces/dry ounce. Re-plotting with that gives you:

Assuming 4 fluid ounces per bottle on average, this means we've used just over 150 bottles so far.

There are a number of recommendations on how much babies should eat (e.g., 2.5 ounces of milk/formula per pound of bodyweight per day), but he seems to not fit those very well. Even though we are breast feeding primarily, he needs a large amount of formula before he's full...particularly during growth spurts. For example...when he weighed 10 pounds, he should have eaten 25 ounces/day which means ~4 ounces/feeding with 6 feedings/day. However, he often required 8-10 ounces of formula after breast feeding. From our tracking of breast milk production, it's very probable that he is getting at least 3 ounces of breast milk per feeding, meaning he's often getting more than 10 ounces in a single feeding. A positive for us is that he sometimes sleeps for >5 hours in a single block because he eats so much in a single feeding. A potential takeaway is that I wouldn't recommend following the general guidelines exactly in every situation.

Another potentially interesting way to look at this data is to convert it into a cost per day:

We don't have the greatest resolution for this data as it's impractical to weigh the formula container every day. However, it is clear from this that his consumption is increasing with time, and that he had a major growth spurt at the beginning of December (~7-8 weeks old).

We expect this cost to continue rising because he'll obviously get bigger and eat more, and we'll be breastfeeding less often once he starts daycare. Thus, the next update will likely come a few weeks after he starts daycare and include a much higher cost.


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