How to partial mash (the easy way)

Learning how to partial mash properly opens a door for kit and extract homebrewers.

Adding raw materials pleases the homebrew gods. They reward you with better homebrew.

The malt profile has depth and the flavors are more rounded.

Let’s cover how to partial mash as simply as we can.

Partial mashing: the best of both worlds

Not everyone wants to be an all grain homebrewer. I get that.

The full day brewing sessions. The expensive and bulky gear. It’s not for everyone.

But every kit and extract brewer has wondered what the appeal is.

For a little extra time and effort, you can dip your foot in the world of homebrewing with grains.

Your homebrew will improve remarkably.

A quick primer on homebrewing with grains

Homebrewing with grain can be a bit daunting, but it’s not as hard as you might think.

If you follow some simple guidelines you can’t go wrong. Here are a couple of things to note:

Wear gloves when partial mashing. It’s hot!

Wear gloves when partial mashing. It’s hot!

  • Be careful and wear gloves—the water is hot and the grain bag is heavy.

  • Have a damp towel handy for spills.

  • Don’t heat wet grain more than 171°F (77°C) otherwise you will extract tannins.

  • Don’t squeeze the grain bag otherwise you will extract tannins.

  • Don’t splash hot wort otherwise your beer will stale more quickly.

  • You will extract far less of the grain’s sweet malt sugars than a regular all grain brewing system.

  • Have a spare two pounds (440 grams) of dry malt extract in case you need to add more fermentables.

  • If you are adding specialty malt, do this after the 60 minute mash.

  • Use a fresh dried yeast to ferment. The resulting wort will have slightly lower oxygen due to boiling. Fresh dried yeast works well in this environment.

  • Check your pot fits in your oven before starting.

There are a few extra things to think about, but don’t stress too much if you miss some of these numbers.

Realistically, unless you seriously screw something up, your beer will be great.

The bulk of the fermentables still come from the malt extract. You are just adding a little more depth and character.

The partial mash process

After nearly two decades of homebrewing, I’ve tried many partial mashing methods with varying levels of complexity.

It turns out the easiest way also gives the best results. A review of the process follows.


Firstly you must mash the grains so starches convert to sugar:

  • Remove all racks from your oven. Set it to around 158°F (70°C).

  • Heat a gallon (4 liters) of water to 162°F (72°C) in a large pot.

  • Sit a large grain bag in the hot water. It should be larger than the pot. Secure this around the rim with string or a large rubber band.

  • Slowly stir in 4.5 pounds (2 kilograms) of crushed malt, making sure it is fully wet and stirred in.

  • Check your mash temperature. If 153°F (67°C) or a few points off, put the lid on and move to the oven. Otherwise, add cold water or heat as need be.

  • Move to oven for 60-90 minutes. Your oven is the easiest way to maintain mash temperature.

Mash out, grain out

Next, you need to perform a mash out and remove the grain bag:

  • Move pot back to oven top and stir in any specialty grains.

  • Slowly heat to 171°F (77°C) and let rest for 10 minutes at this temperature.

  • Slowly lift the grain bag, letting the liquid drain into the pot.

  • You can sit the grain bag sit in a large colander placed in the pot to make the job easier.

Boil, mix, cool

You then boil and cool the malty liquid:

  • Bring to the boil (have a spray bottle filled with cold clean water for boilovers).

  • Boil for 30 minutes. Add any flavoring hops with 10 minutes before flameout. Add aroma hops with one minute to go.

  • Switch heat off and mix in your tin of homebrew concentrate.

  • Sit in an ice bath to cool.

Mix up and now over to you

Once the pot is cool enough to touch, mix the sweet wort with cold water in your fermenter. Leave most of the solid material in the pot, but it’s OK if some get in the fermenter.

Check your wort’s gravity. If low, add in extra malt extract to bring up to your target original gravity.

From here it is business usual for the kit or extract brewer. Pitch your yeast and ferment as you normally would.

Happy homebrewing!

Mix the partial mash wort with cold water in the fermenter, leaving the solids behind in the pot.

Mix the partial mash wort with cold water in the fermenter, leaving the solids behind in the pot.

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