The Cowculator


It’s time people. For the second installment of our series on milk, we give you “The Cowculator”.

The Cowculator figures out the precise breakdown of coffee, fat, protein and sugar in your milky drinks. You can use it for both drip/filter and espresso based coffees, and it’ll adapt to any type of milk.

I’m always a fan of gathering numbers and data about the drinks I serve. The more data you have, the better you can understand and optimise. With a little experimentation, the Cowculator can help you:

  • make decisions about which milk to buy
  • optimise your espresso recipe for more/less coffee flavour
  • learn about the diluting/concentrating relationship of milk and foam
  • achieve consistency in flavour across different cup sizes

Adjust the blue numbers to match your drink, or just play around to see how it works. Extra instructions and discussion below.

Here’s what the Cowculator needs from you:

  • How much liquid coffee is in the cup, in grams.
  • How strong that coffee is (tips for those without a refractometer below).
  • How much milk in is in the drink, in grams.
  • The amount of fat, sugar and protein in your milk, found on the nutritional information label. (Make sure you’re reading from ‘g/100ml’, not the ‘per serve’ column).

The easiest way to measure the coffee and milk is to:

  1. Tare/zero your cup on a set of scales.
  2. Pour the coffee in and note its weight.
  3. Tare/zero the cup and coffee.
  4. Pour the milk in and take note of its weight.

With that information on hand, the Cowculator will be able to provide you with the weight and strength (concentration) of every component in the drink. It’ll also give you a total solids concentration and amount of water in the drink.

Here’s an example of a Cappuccino I had this morning at St Ali:

Cowculator Example

Let’s go through the numbers:

Coffee – Interestingly, our cappuccinos end up with a coffee strength that’s very similar to our filter/drip coffees. Coincidence? Probably not. We chose this espresso and cappuccino recipe at St Ali because it’s deliciously balanced.

Fat – This milk is super fatty, and the finished drink ends up with more fat than a lot of whole milks start with! Fat is delicious. I love fat.

Lactose – There’s nearly 3 times as much lactose as there is coffee. This is massive, and is the main reason our cappuccinos taste super-sweet. Remember though, that Lactose is only 16% as sweet as table sugar.

Protein – 3.5% is within regular limits. I don’t have too much experience with tasting differences in protein. It’s definitely doing its job helping out with foam stabilisation. If anyone has more knowledge about protein I would love to hear your thoughts in the comments!

Totals – Our cups are 150ml volume, but this drink only weighs 130.5g. This is because the air inside the foam fills up the rest of the cup.

Tip: The more air there is in your foam, the stronger the coffee flavour will be. Air doesn’t dilute coffee, but it sure does fill the cup. This is why a cappuccino is stronger than a flat white in the same size cup!

If you don’t have a refractometer, assume that drip/filter coffee is 1.4%. For espresso, you can make a (very) rough guess with this simple formula:

11 – (Yield / Dose) = % TDS
eg: 11 – (40g / 20g) = 9% TDS
11 – (55g / 22g) = 8.5% TDS

Dose = weight of your dry coffee grounds in the basket, in grams.
Yield = weight of your full espresso (both spouts), in grams.

Feel free to share your numbers in the comments. I’m looking forward to checking out your chinos!

This calculator doesn’t take the ‘Ash’ or mineral portion of milk into account because it’s not quantified on the nutrition label. It also assumes that the density of fat/protein/sugar is 1kg/m3. They’re not, but the density of milk averages out to 1030kg/m3 so I’m considering it a rounding error—flame at will!