Running low on sour milk? Here are the best verified substitutes, including how to adjust your measurements.

About sour milk
Sour milk is fresh milk that has been acidified, either naturally through bacterial fermentation or intentionally by adding an acid such as lemon juice or white vinegar. It plays an important role in baking, where its acidity reacts with bicarbonate of soda to provide leavening and tenderise the crumb. Sour milk imparts a subtle tang and contributes moisture to baked goods such as pancakes, scones, and quick breads.
Best substitute
Buttermilk is the closest match to sour milk in both acidity and flavour, making it an ideal direct swap in virtually any recipe. It has a similar tangy profile and reacts with bicarbonate of soda in exactly the same way.
Alternative
Stir 1 tablespoon of fresh lemon juice into 1 cup of full-cream milk and allow it to stand for 5–10 minutes until slightly curdled and thickened. This mimics the acidity and texture of sour milk reliably and is the most convenient DIY option.
Alternative
Add 1 tablespoon of white vinegar to a measuring cup, then top up with full-cream milk to the 1 cup mark. Stir and leave for 5–10 minutes until lightly curdled. White vinegar is more neutral in flavour than lemon juice, so it won't add any citrus notes.
| Country | Name |
|---|---|
| Australia | sour milk |
| United Kingdom | sour milk |
| United States | sour milk |
| ZA | amasi |
Alternative
Whisk together three-quarters of a cup of plain full-fat yoghurt with a quarter cup of milk to achieve a pourable consistency similar to sour milk. Yoghurt is more acidic and thicker, so thinning is essential to avoid a dense result.
Alternative
Plain, unflavoured kefir is a fermented milk drink with a similar tangy acidity to sour milk and a naturally thin consistency. It can be used as a direct substitute and works particularly well in baked goods where a slightly more complex fermented flavour is acceptable.