I followed this recipe to make condensed milk but it never thickens.

2 cups milk
1/2 cup sugar
25 gr butter

I tried it once following the recipe to a T, and when it didn't thicken not even a little bit after 30 minutes, I decided to halve the recipe and use a big frying pan so that it would thicken faster. It didn't thicken, again. It never thickens and the consistency is exactly like the milk itself.

I mix sugar with milk, then on medium heat constantly stir. After about 20-25 minutes, half of the milk was evaporated but the thing didn't thicken! What am I doing wrong?

  • 1
    If half of the milk has evaporated AND you've added the sugar, it has definitely thickened. What could be happening is that the heat has made it runnier than you're expecting. Assuming you've reached the post-reduction volume you're aiming for, let it cool before judging the final consistency.
    – Abion47
    Commented Oct 30, 2023 at 22:55
  • @Abion47- Well, at the end it is slightly thicker than milk and is in no way comparable to the consistency of store bought condensed milk. I could have left it on the heat even longer but I didn't, it is already too sweet for my taste, could have been sweeter if I let the milk eaporate even more.
    – Gigili
    Commented Oct 31, 2023 at 12:56
  • Are you using whole milk?
    – KnotWright
    Commented Oct 31, 2023 at 17:00
  • @KnotWright__ It says "fresh milk 3.8% fat" on the label.
    – Gigili
    Commented Oct 31, 2023 at 20:45
  • It's not clear whether you've done what @Abion47 suggests, and let it cool to ruin temperature before testing. I've only used tinned condensed milk, but I know that the consistency changes a lot if you warm it up. It's not melting as such, because it's liquid at room temp, but it's rather like melting
    – Chris H
    Commented Nov 2, 2023 at 20:33

3 Answers 3


This Nutrition Facts table for sweetened condensed milk lists 166g of sugar per cup.
Perhaps some of that comes from the naturally occurring lactose in the milk, but probably not a significant amount compared to the added sugar.

You're only putting about 100g of sugar in to your mix and then reducing the volume by half.
So you're probably starting off with a little over 2 cups, and reducing it down to a little over 1 cup, but you're still left with substantially less sugar in that 1 cup of reduced product - probably only a little over half the amount indicated above.

I suggest increasing the amount of sugar to at least 3/4 cup.

  • There's apparently about 13g of lactose per chip of milk so more like 3/4 than half the sugar - if they're reducing it to 1 cup, and reducing by half won't do that because of the volume of the sugar.
    – Chris H
    Commented Nov 2, 2023 at 20:31
  • Well, I think I didn't explain it well. I tried to make condensed milk twice. Once I followed the recipe and it didn't thicken at all, went directly to the trash. Another time I halve the recipe and the consistency was only a little bit thicker than the milk.
    – Gigili
    Commented Nov 2, 2023 at 21:02

You said 20-25 minutes, this is way too short.

When you are reducing milk, you have to use a really low temperature to avoid caramelization. It shouldn't even be simmering. You have to watch it to know when it's done, but the correct time should be in the range of 6 to 12 hours.

It will be a bit fiddly to get it to work without accidental browning (or worse, scorching) but with enough oversight, the end product should be acceptable.

  • The recipe claims 30 minutes would be enough. 6 to 12 hours?? There remains nothing in the pan after six hours!
    – Gigili
    Commented Nov 6, 2023 at 5:43
  • @Gigili Your task is to stop the heating between the point where it's still too liquid and the point when there's "nothing" left (actually, it will never be nothing - worst case, there will be charcoal at the end). You should also do it as slowly as possible, because if you don't, you'll end up with fudge instead of condensed milk. Evaporating milk over many hours is absolutely normal, while 30 minutes aren't at all useful; if you heat milk to boiling temperatures over 30 minutes, it doesn't lose much water, despite ending up too hot for the condensation process.
    – rumtscho
    Commented Nov 6, 2023 at 11:55

If I need a thicker consistency I would add some skimmed milk.

  • 1
    Sounds counter-intuitive. Can you explain, why?
    – Stephie
    Commented Nov 8, 2023 at 5:00

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