I need close to 900 ml of cream 30–35 % for a mousse recipe (which requires part of the cream to be whipped). Is it possible to dilute double cream (48 % fat) with whole milk (3.6 %) to get an average in the range I want?

Using the numbers above, I calculated that mixing 600 ml of double cream with 300 ml of milk should give me 900 ml (if they add up like that) of something with 299 g of fat, which is about 33 %.

Does this make sense or are there any complications I need to be aware of?

Note: The cream/milk packages actually give grams of fat per volume (e.g., 100 ml of double cream has 48 g of fat), but I've taken it to be about the same as percentage by mass since the target fat content is a range rather than an exact figure.

APPENDIX: Since this was mentioned in the answers/comments and it might be useful to other people, here's the formula I used to calculate the necessary quantities to achieve the target fat percentage.

Given two milk or cream liquids with different fat percentage (I will refer to the one with lower fat content as "thin" and the one with higher fat content as "thick"), a liquid quantity Q_target and fat concentration TargetFatConcentration can be achieved by mixing


The fraction is a ratio (pure number), but I'm using the word "concentration" instead of "percentage" (which is normally used for fat content) because the products you have (as in my case) might be giving you grams of fat per volume, which is, technically, not a percentage. The point is that units need to be consistent, whatever they are.

Either volume or mass can be used for the "quantities".

It should go without saying that the target concentration can only be between the "thin" and "thick" one; i.e., you cannot dilute a cream by adding a thicker cream to it and vice versa.


3 Answers 3


This will work just fine. Many people will get the math wrong, but your calculations appear correct. Give it a good stir and everything should come out as expected. Most recipes are sufficiently tolerant that substituting the double cream would likely be fine compared to just using the heavy (if not an improvement).

  • 4
    The only concern would be where the cream is used without any cooking or modifications, like on fruit for example, as the fat won't be completely mixed. However just mixing very thoroughly should fix that.
    – GdD
    Aug 7, 2018 at 15:55
  • 1
    @GdD, part of it will be whipped and then "cooked" into a mousse, so sounds like it should be OK.
    – Ratler
    Aug 7, 2018 at 17:36
  • That's fine, I do that all the time @Ratler
    – GdD
    Aug 7, 2018 at 20:03
  • 1
    I've already tried it, and I got a very nice mousse! So it does seem to work.
    – Ratler
    Aug 10, 2018 at 11:11

Technically, double cream has a minimum fat content of 48%, and could be higher, which might throw your numbers off. That’s unlikely with cream from a large commercial supplier, since they can always make more money by diluting it down to 48%, but I buy unpasteurised double cream pretty much straight from the cow from a local dairy farm, and I have to dilute it with milk for recipes that call for double cream, never mind single.

  • True, which is why I check the information on the package for the exact figures rather than going by generic names such as "double cream", "heavy cream" etc.
    – Ratler
    Aug 7, 2018 at 22:21

That is the number I get:

600 ml × 0.48 = 288 ml
300 ml × 0.036 = 10.8 ml
(288 ml + 10.8 ml) / 900 ml = 33.2%

I think they would mix fine but I'm not positive on that. Mixed in recipe with dry goods like flour for sure they should mix.

Volume versus mass would be very close to the same here as density is close, if not the same.

  • Those are the exact figures I got. The mixture will go into a mousse, so no flour there, but it will be whipped/heated well.
    – Ratler
    Aug 7, 2018 at 17:39
  • @Ratler you should have mentioned that you're whipping, that's one of the cases where the substitution might or might not work.
    – rumtscho
    Aug 8, 2018 at 6:26
  • Mixing butter and milk to make cream is tricky (but possible), but the fat in cream is still the same sized microscopic droplets suspended in the same watery medium as milk - it's just the ratios which are different. Just stir and they should be mixed fine. Aug 8, 2018 at 15:45
  • @rumtscho, I'll update the question to mention whipping, but I've already tried it and it seems to have worked perfectly fine.
    – Ratler
    Aug 10, 2018 at 11:02

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