The Best Jars for Overnight Oats (2025 Guide: Sizes, Features & Types)
Overnight oats have gone viral and it’s no surprise. They’re healthy, endlessly customisable, and take less than five minutes to prep. From TikTok trends to meal prep routines, this no-cook breakfast has become a staple for busy mornings and better eating habits.
But here’s the part nobody talks about: the jar itself makes all the difference.
A great jar can:
- ✅ Speed up your morning with quick, no-mess prep
- ✅ Avoid leaks that ruin your bag, outfit, or day
- ✅ Make eating more enjoyable through high-quality materials and thoughtful design
In this guide, we’ll break down what to look for in the perfect overnight oats jar - including size, shape, material, and the one feature that often gets overlooked but matters most:
👉 the quality of the lid.
What Size Jar Should You Use for Overnight Oats?
When it comes to overnight oats, jar size matters more than you might think. Too small, and you’ll end up with a mess. Too large, and your oats will look lost at the bottom.
Here’s a breakdown of the most common jar sizes:
🥣 250ml (8 oz) - Small Jar
- Ideal for kids or light eaters
- Great for basic oat + milk mixes
- Can feel cramped with toppings or mix-ins
🥄 350ml (12 oz) - Medium Jar
- Perfect for a standard single serving
- Leaves space for fruit, yoghurt, nut butters, or protein
- ✅ This is the size used in the OATOLOGY Jar
🥛 500ml (16 oz) - Large Jar
- Good for big appetites or double servings
- Great for smoothies or parfaits
- Bulkier and takes up more fridge space
Tip: A typical serving of rolled oats is 50g (½ cup) with 100–150ml (½–⅔ cup) of milk. A 350ml (12 oz) jar gives you just the right amount of space for oats, liquid, and toppings.
Glass vs Plastic – Which Material Is Best for Overnight Oats?
The material you choose isn’t just about looks - it impacts safety, taste, and sustainability.
✅ Glass Jars
- BPA-free, non-toxic, and food safe
- Doesn’t absorb flavours or odours
- Dishwasher-safe and long-lasting
- Recyclable and eco-friendly
- Stylish, clean look
❌ Plastic Containers
- Lightweight but may contain chemicals like BPA
- Prone to staining and odour build-up
- Can degrade, crack, or warp over time
That’s why we chose durable, leakproof glass for the OATOLOGY Jar - it’s cleaner, safer, and built to last.
Must-Have Features in an Overnight Oats Jar
A good jar doesn’t just hold your oats. It makes your mornings easier, your food fresher, and your routine smoother. Here’s what actually matters when choosing the right one:
🔒 A Lid That Works (and Stays That Way)
This is the most important part - and also the one most brands get wrong.
A poor-quality lid means leaks, messes, and frustration.
A great lid means:
- A tight, reliable seal (no guessing or checking)
- Easy to screw on and off
- No drips in your bag or fridge
- Built to last with durable materials, not cheap plastic
At OATOLOGY, we spent just as much time designing the lid as the jar itself - because your whole morning depends on it.
💎 Durable, High-Quality Glass
We use thick, toughened glass that:
- Resists cracking, scratching, and thermal shock
- Stays clean and neutral (no smells or stains)
- Feels solid and premium in your hand
🍴 A Jar That Fits You
A wide mouth makes prep, eating, and cleaning simple.
Built-in measurement guides mean perfect portions - no guesswork.
When your jar is designed properly, it becomes part of your routine. It doesn’t get in the way - it helps you stay on track.
Types of Jars for Overnight Oats (With Pros & Cons)
From minimalist glass jars to plastic pudding cups, here are the most common types people use - and how they compare.
🫙 Classic Jars / Mason Jars
- ✅ Affordable and durable
- ❌ Narrow mouths and tricky lids
🫗 Clamp-Top Jars (Kilner Style)
- ✅ Airtight seal
- ❌ Bulky and fiddly to open
🫙 Minimalist Pantry Jar
- ✅ Stylish and modern
- ❌ Often lacks seal or spoon
🍦 Yoghurt-To-Go Cup (Image 2)
- ✅ Lightweight with built-in spoon
- ❌ Usually plastic, prone to leaking
🥄 Mason Jar with Spoon Clip (Image 3)
- ✅ Handy for commuters
- ❌ Spoon often gets lost or dirty
🎋 Bamboo Top Jar
- ✅ Cheap
- ❌ Thin glass & not portable
💡 Pro tip: The best all-rounder is a 350ml (12 oz) wide-mouth glass jar with a spoon and a secure lid - just like the OATOLOGY Jar.
Why We Designed the OATOLOGY Jar the Way We Did
We tested dozens of jars. None had everything we wanted - so we made one that did.
The OATOLOGY Jar is built for real, everyday use. Every feature solves a real problem:
- ✅ Leakproof stainless steel lid with BPA-free silicone seal
- ✅ Scoop-lid for measuring oats perfectly
- ✅ Wide mouth for easy eating and cleaning
- ✅ Clip-on stainless steel spoon for convenience
- ✅ Dishwasher-safe, durable glass - built to last
If overnight oats are part of your routine (or you want them to be), this jar makes it easier, tidier, and honestly - more enjoyable.
Frequently Asked Questions About Overnight Oats Jars
Can I use any jar?
Sure, but for regular use, a wide-mouth, leakproof glass jar is a game-changer.
Do I need glass?
It’s safer, more durable, and better for taste and the environment than plastic.
What size should I use?
Most people prefer 350ml (12 oz). Bigger jars work too, but can feel bulky.
How do I clean it?
Use warm water, or toss it in the dishwasher if it's glass and wide-mouthed.
Is a spoon really necessary?
Yes - especially if you eat breakfast at work or on the go. That’s why we include one.
Final Thoughts: A Better Jar = A Better Breakfast
Overnight oats are already easy. The right jar makes them effortless.
If you want to:
- Save time
- Eat healthier
- And make your mornings simpler...
Then a jar built for overnight oats is the upgrade you didn’t know you needed.
👉 Ready to Upgrade?
Shop the OATOLOGY Jar - Premium glass, perfect size, no leaks, no stress.