The journal

Overnight oats: ratios, soaking time and storage

The overnight oats ratio that works, which oats to use, why they soak in the fridge and how long a batch keeps.

By Stirred Daily editorial team · 2026-09-26

Jars of overnight oats topped with berries and banana beside a bowl of rolled oats on a wooden kitchen counter

Quick answer: the overnight oats ratio

Use one part rolled oats to one part milk by volume, for example half a cup of oats with half a cup of milk. Stir, close the jar and refrigerate overnight. If you add yogurt, count it as part of the liquid; if you add chia seeds, add a little extra liquid because they absorb it too. Weighing is more repeatable than cups: around 45 g of oats to 120 ml of milk makes one generous jar, and our note on weighing and scaling a recipe shows how to multiply it for the week.

Which oats work, and why

Rolled (old-fashioned) oats have been steamed and flattened, so they soften fully in a night of soaking and keep a little texture. Quick oats soften faster and turn creamier, sometimes mushy. Steel-cut oats are whole groats cut into pieces; they stay firm after a night in milk and are better cooked, which our simmer technique covers.

Oats for overnight soaking
Oats	After one night	Best use
Rolled (old-fashioned)	Soft, still some bite	The standard overnight jar
Quick or instant	Very soft, creamy	If you prefer a porridge texture
Steel-cut	Still chewy and firm	Cook on the stove instead

Hands stirring rolled oats and milk together in a glass jar beside a kitchen scale and a small jug of milk

Soak it in the fridge, not on the counter

Overnight oats are a raw grain sitting in milk for hours, so where they sit matters more than the recipe. North Carolina Cooperative Extension points out that a jar left at room temperature overnight can let bacteria grow, while the same jar in the fridge is not a problem (NC State Extension: overnight oatmeal safety). The USDA's rule of thumb is to refrigerate perishable food within two hours, because bacteria multiply fastest between 40°F and 140°F (USDA: the danger zone).

Measure the oats and liquid into a clean jar.
Stir well, scraping the corners so no dry pockets remain.
Close the lid and put the jar straight into the fridge.
Leave it for at least six to eight hours, then stir again before eating.

How long a batch keeps

Prepared overnight oats are a leftover as far as storage goes. The USDA advises keeping refrigerated leftovers for three to four days (USDA: leftovers and food safety), so making four jars on Sunday covers most of the week. Texture changes before safety does: the oats keep softening, so keep crunchy toppings such as toasted nuts in a separate container. Our guide to toasting nuts in the oven makes a batch that lasts all week.

Oats in the evening

Overnight oats are usually breakfast, but a small bowl also works as a light evening snack. TalkAboutSleep looks at what the evidence says about eating oatmeal before bed, including how long before bedtime to eat it.

Overnight oats, step by step

Rolled oats and milk in a 1:1 ratio
Extra liquid if using chia or yogurt
Stirred, lid on, straight into the fridge
Soaked at least six to eight hours
Toppings kept separate until serving
Eaten within three to four days

Frequently asked questions

Can I leave overnight oats on the counter?

No. Oats soaked in milk should go into the fridge within two hours; at room temperature bacteria can grow overnight.

Can I use water instead of milk?

Yes. Water gives a lighter, less creamy result; plant milks and yogurt work too. Keep the jar in the fridge whatever the liquid.

Can I warm overnight oats?

Yes. Heat them gently in a pan or the microwave, stirring, and add a splash of milk if they have thickened too much.