How To make Buttermilk

All you need is 1 cup of milk and 1 tablespoon of lemon juice or white vinegar. That's it. Here's how it comes together.

A hand holding a measuring jug with milk in it.

Step 1: Pour the milk into a jar or bowl. Full cream milk gives the thickest result, but any milk will do.

A shot looking into a small bottle filled with cultured milk.

Step 2: Add the lemon juice or vinegar and stir it through. Just a regular stir with a spoon is all it needs.

A small jar placed on a tea towel and filled with buttermilk.

Step 3: Leave it on the bench for 5 minutes. It'll go slightly thick and curdled looking. That's exactly what you want.

Overhead shot looking down on a bottle filled with buttermilk.

Step 4: Give it one last stir and use it straight away. Your homemade buttermilk is ready to go.

Team Thermomix? Weigh the milk and lemon juice (or vinegar) straight into the mixing bowl and mix 30 sec/speed 1 to combine, then leave it in the bowl for 5 minutes to thicken, same as the stovetop version. One bowl, no extra dishes.

Buttermilk Ingredients

Vinegar, milk and a lemon on a white background.

You really only need 2 things: milk, and something acidic.

Lemon juice vs white vinegar - either works, and the end result is basically the same. Lemon juice gives a slightly fresher, more citrusy edge, while white vinegar is more neutral and won't add any flavour at all. I just use whatever's closest to hand.
Milk - full cream milk gives the thickest, richest buttermilk, but reduced fat and skim both work fine too. Just note the thinner the milk, the thinner your buttermilk will be.

Variations

No milk and vinegar on hand? Buttermilk powder mixed according to the packet works a treat, and it's worth keeping a tin in the pantry if you bake often.
Sour cream or natural yoghurt - thin it out with a splash of milk until it's pourable. Works well in cakes and muffins, though it's a bit thicker than the real thing.
Got kefir in the fridge? It's a straight 1:1 swap for buttermilk, no acid needed at all.
Dairy-free? Use soy or oat milk with the same tablespoon of lemon juice or vinegar. I'd steer clear of almond milk here, it can curdle strangely and doesn't thicken properly.

Recipe Tips

Storage: keep it in a sealed jar or container in the fridge for up to 14 days.
Freezing: pop it in the freezer for up to 3 months. It goes a bit grainy once thawed, but it's still totally fine to bake with, just give it a good shake or stir first.
Not thickening? Your milk was probably too cold. Let it sit on the bench a bit longer, or start with milk that's closer to room temperature.
Need a smaller amount? 1 tablespoon of vinegar or lemon juice is the same as 3 teaspoons, so you can easily scale the whole thing down for a smaller quantity.

What Is Buttermilk And What Can You Use It For?

Traditionally, buttermilk was just the liquid left behind after churning cream into butter. These days, the buttermilk you buy at the supermarket is actually cultured milk, meaning it's had a bacteria added to it that makes it thicken and turn slightly tart and acidic, kind of like a mild yoghurt. The homemade version in this post isn't exactly the same thing (there's no culturing happening, just a quick reaction between the milk and the acid) but it behaves the same way in almost every recipe, which is really all that matters.

So what does it actually do in your baking? The acid in buttermilk reacts with bicarb soda to help things rise, which is why pancakes and scones made with buttermilk come out noticeably fluffier and lighter than the same recipe made with regular milk. In cakes, it breaks down the gluten a little, giving you a softer, more tender crumb. And in biscuits, it's the difference between a dry, crumbly result and one with a bit of a melt-in-your-mouth texture.

It's not just for sweet baking either. The acidity makes it brilliant for marinating meat (it gently breaks down the proteins, so your chicken ends up more tender), and it makes a great base for a tangy, creamy salad dressing if you whisk it with a bit of mayo, herbs and garlic.

Buttermilk FAQs

Is lemon juice or vinegar better for making buttermilk?

Honestly, either is fine. Lemon juice gives a slightly fresher, citrusy note, while white vinegar is more neutral and won't change the flavour at all. They both thicken the milk the exact same way, so pick whichever you've got open in the pantry.

How long does homemade buttermilk last?

Kept in a sealed container in the fridge, it'll last up to 14 days. You can also freeze it for up to 3 months if you want to make a bigger batch. It gets a bit grainy after freezing, but it's still perfectly fine to bake with.

Can I make dairy-free buttermilk?

Yep. Swap the milk for soy or oat milk and use the same tablespoon of lemon juice or vinegar. I wouldn't bother with almond milk though, it tends to curdle oddly instead of thickening properly.

Can I use buttermilk in savoury cooking, not just baking?

Definitely, it's not just a baking ingredient. It's great for marinating chicken (the acidity tenderises it beautifully), and it makes a lovely tangy base for a creamy salad dressing.

Can you freeze buttermilk?

Yes, homemade or store-bought, it freezes well for up to 3 months. The texture goes a little grainy once it's thawed, but it works exactly the same in your baking, just give it a good stir or shake first.

More Recipes To Use Your Buttermilk In

Now that you've got a jar of homemade buttermilk sitting in the fridge, here's where a splash of it works brilliantly in place of regular milk.