Being fairly new to used starters, I'm somewhat confused as to how much volume of water to boil when adding DME to create a starter. For instance, if the Kalkulator I'm using says to start with 2 L of water and add 8 ounces of DME and boil for 10 to 15 minutes, I will only have approximately 1.5 L of water at the end of that process. Does that mean I need to add back in another half liter of sterilized water to get to my 2000 mL volume from the calculator?

2 Answers 2


Yes, starter calculators are a post boil volume.

Your boil off depends on what you're boiling in (surface area mainly) and how hot you boil it.

Do a test to see how much your vessel and burner boils off in 15 min, then add that volume to your total starter volume for you wort boil.

I boil right in the flask and only get about 100-200ml boil off.

  • Also new to yeast starters (cf my question about light). Boil off wasn't something I'd been accounting for. Will do that next - thanks! (I've been using a saucepan on the hob for boiling)
    – winwaed
    Mar 2, 2016 at 14:36
  • I would recommend boiling in the flask, or at least baking the flask to sterilize. If you just starsan between uses, you will still get residual yeast from the previous starter. Mar 4, 2016 at 15:01
  • I'll give it a go. I know it is pyrex, but I'm wary of thin glass on a hot heat source...
    – winwaed
    Mar 4, 2016 at 17:23
  • @winwaed Pyrex or tempered glass flasks are made for quick temp changes. You can go right from burner to ice bath. Fyi, need to hear with gas, electric just doesn't work well. Mar 4, 2016 at 18:18
  • I know (and we heated pyrex with bunsens at school & univ), but it still doesn't feel right :-) [actually I did break some pyrex boiling tubes with suck back]. At the moment I don't really have a choice on the heat source. I have invested in propane for the main boil, but that is serious overkill for a flask - I doubt it would fit on the top of the burner. We're only talking about a litre or so, so it doesn't take too long on an electric hob or with an electric kettle to get it started. (and our camping stove is meths based)
    – winwaed
    Mar 5, 2016 at 14:51

I don't know your calculator. No one here knows unless you will link to it. So we cannot tell what it's developers had in mind.

That said, you want about 1.040 OG / 10 Blg after boil. If that means starting with 2 liters and boiling it to 1.5, do it. If this means starting with 3l and boiling down to 2? So be it.

The one you linked gives you post-boil volume (verified using Brewtarget). But that's not the point. The point is to know what you are doing and what you need - and that's certain volume and certain gravity when you add your yeast.


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