Making a yeast starter is a great way to cut costs while making a delicious, high-gravity beer. And it’s WAY LESS COMPLICATED than it’s made out to be.
In this guide, we’ll show you how to make one in 20 minutes with minimal beer brewing equipment. But pay special attention—sanitation is KEY.
If you’re just getting started with homebrewing, learning how to make it is crucial.
You’ll make better beer, save money, and maybe even save an entire batch of beer from tasting like your dad’s Bass Ale fresh out of the trunk (we explain that next).
Here’s everything you need to know:
What is a Beer Yeast Starter?
All you really need to know about a beer yeast starter is that it is basically a “mini batch of beer” except without the flavor (hops, etc.).
Pretend you’re making a batch of beer like you normally do but then skipping all of the stuff that makes it good….
A good starter serves 3 purposes:
- Increase the Amount of Yeast to Ferment Your Beer: Buying packets of dry yeast adds up over time and most liquid yeast isn’t ready for the pitching rates. A cup of dried malt extract is basically free. The fermentation can essentially double the available yeast cells to ferment your beer at a fraction of the cost. 
- Rehydrating Yeast: You know how you keep yeast in the fridge so it doesn’t degrade? When you’re ready to brew again, you’ve got to reactivate it. Think of it like taking your it out of hibernation.
- Yeast Proofing: You can use your starter to check if it is still viable for brewing. If it’s been sitting around too long, it might be useless. Trust us, the last thing you want to do is brew a 5-gallon batch and have it taste like Drain-O. How to proof yeast would be another topic for discussion.
“A starter is a way to proof your yeast. If you have yeast that has been sitting around for a long time, you want to make sure it is still viable. If it is completely dead, you’d rather find out in a starter than in a 5 gallon batch of beer.”
– Billy B., Brewer
Pro Tip: When proofing yeast, wait 5 to 10 minutes and see if the starter begins to foam up. If so, you’re good to go. If not, you need new yeast.
Here’s our guide on beer yeast and how to choose the perfect yeast strain for your beer.
How to Make Yeast Starter in 3 Steps
Step 1: Equipment
Your starter wort does not have to be perfect. You don’t need all of the fancy bells and whistles. You only need a few specific pieces of equipment:
Note: This is for a 1-liter starter
- Magnetic Stir Plate with Bar (~$50)
- Sanitized Laboratory-Grade Erlenmeyer Flask (you could use a saucepan but using just one vessel makes cleaning and production WAY easier)
- Sanitized Erlenmeyer Flask Cover (foam stopper recommended)
- Hydrometer (for checking gravity)
- Dried Malt Extract (DME)
Step 2: The Process
The process on how to activate yeast cells is way simpler than most recipes make it seem. Remember, this is a homebrew, not a craft beer exposition. 
Ratio: For every 10 ml of water, use 1 gram of DME. So for 1-liter of water, use 100 grams of DME.
- Fill your flask with 1200ml of water. Since some water will boil off, you have to overfill the flask by 100-200ml.
- Pour your DME and boil the solution for 10-15 minutes.
- Stir vigorously every few minutes by shaking the flask. Be sure to watch the flask so it doesn’t foam over.
- Prepare an ice bath in your sink.
- After 10-15 minutes (the solution will be clear), cool the solution down to 70-75 ℉ in the sink. This shouldn’t take more than 10 minutes. Make sure to give her the ol’ swirl and dunk in and out of the ice water.
- Test the gravity of your starter with your hydrometer. A gravity of around 1.040 should be fine for most types of beer and alcohol.
- Pour the starter on the stir plate and add the sanitized yeast nutrient.
Warning: Even though the yeast packet is airtight, sanitize the outside of the packet with a solution to ensure you don’t infect your beer. It takes no time at all. JUST DO IT.
Step 3: Let the Stir Plate Work its Magic
From here, just place the starter on the stir plate and let it go to work. Let it stir for your chosen amount of time (we explain how long below) and you’ve got your finished product ready to go. There are generally two techniques that beginners use when brewing with a starter:
- Leave it stirring until you brew: If you time it right, you can leave your starter on the stir plate until right before you pitch. Some claim this makes the healthy yeast cells ravenous and ready to ferment like a boss. Make sure it’s at least 12-14 hours.
- Leave it for longer and put it in the fridge: If you aren’t ready to pitch, you can leave it stirring for up to 20 hours, place it in the fridge for a day or two, take it out, and let it warm up to room temperature before the pitching rate. This is called “cool crashing” and you can find a lot of information around the web if you want to research it further. In our opinion, you don’t need to get fancy for basic homebrewing.
You can also watch this tutorial from Clawhammer Supply as a supplementary guide on how to make a starter yeast.
Yeast Starter: Conclusion
It really all comes down to your preference and what you think is easiest. As with all things brewing, it’s about experimentation.
The more you brew the more refined your process will be and this equip you with a skill on how to tell if yeast is good or not.
If you want the easiest way to increase cell count for fermentation temperature, rehydrate, or proof your yeast nutrients, a starter is the way to go.
You can have one ready to stir in about 20-25 minutes, and it costs next to nothing in terms of ingredients. Using a starter will help you brew better beer and avoid beer disaster (remember that piping hot Bass Ale we were talking about?).
Have you ever had a disaster on your brew day? Did a starter help you the next time around. We hope so. Let us know if this method helped you as a brewer to make a great yeast starter in no time!