Bedding listings often assume you already know the difference between a flat sheet and a fitted sheet. If you have ever stood in front of a size chart wondering whether you need one, the other, or both, you are not alone.
The short answer: a fitted sheet covers your mattress, and a flat sheet goes over you. They do different jobs, and whether you need both depends on how you sleep and how warm your bedroom gets.
This guide explains what each one does, when you can skip one, and how to build a sheet setup that works through summer and winter.
What Is a Fitted Sheet?
A fitted sheet is the sheet that wraps around your mattress. It has elastic sewn into the edges so it grips the corners and stays in place while you move during the night.
This is the layer your body is in contact with for most of the night, which makes it the most important piece for comfort. If the fitted sheet traps heat or feels rough, no amount of adjusting the blanket on top will fix it.
An organic muslin fitted sheet uses an open weave that lets air move through the fabric rather than sitting against your skin. It also has a naturally relaxed, slightly crinkled surface, which means no ironing.
What Is a Flat Sheet?
A flat sheet, sometimes called a top sheet, is a plain rectangle of fabric with no elastic. It sits between you and whatever is above you, whether that is a blanket, quilt or duvet.
A flat sheet does three useful things. It gives you a light layer you can use on its own when the room is warm. It keeps your blanket or duvet cover cleaner, since your skin touches the sheet rather than the heavier layer. And it lets you adjust your warmth without changing the whole bed, simply by folding it back or pulling it up.
Our organic muslin flat sheet is made from the same Turkish cotton as the fitted sheet, so the two feel consistent when used together.
Do You Need Both?
Not necessarily. Here is how it usually breaks down.
You need a fitted sheet. There is no real substitute. It protects the mattress and creates the surface you sleep on.
A flat sheet is optional but useful. Many people in the United States use both. In much of Europe, it is common to skip the flat sheet and use a duvet cover directly, washing the cover more often instead.
A flat sheet is worth having if you sleep warm and want a layer you can use alone on hot nights, if you want to wash your duvet cover less frequently, or if your bedroom temperature swings between evening and early morning.
You can reasonably skip it if you use a muslin duvet cover and wash it regularly, or if you simply prefer fewer layers to make.
Using Both Together Through the Seasons
The advantage of owning both is that your bed becomes adjustable rather than fixed.
On the warmest summer nights, a fitted sheet plus a flat sheet is often enough on its own. As nights cool slightly, add an organic muslin blanket folded at the foot of the bed, so you can pull it up if you wake cool at 4 a.m. In colder months, keep both sheets as your base and add a quilt or duvet cover above them.
This is a more useful approach than swapping your entire bedding twice a year. The sheet layer stays the same, and only what sits above it changes.
Getting the Size Right
For a fitted sheet, the important measurement is not just the mattress width and length but its depth. Mattresses have grown thicker over the years, and a sheet cut for a shallow mattress will pop off the corners on a deep one.
Measure your mattress depth before ordering. Naturloom fitted sheets are made for standard US mattress sizes, and we also make custom sizes for customers whose mattresses fall outside those measurements. If you are unsure, email us before ordering rather than guessing.
For a flat sheet, size is more forgiving, since it simply drapes. The question is how much overhang you want on each side.
Colors That Work Together
Our muslin sheets come in Ivory, White, and four soft stripes: Sage Green, Anthracite Grey, Taupe and Terra Cotta. Because the stripes are woven in low contrast, they read as texture rather than pattern from across the room, which makes them easy to pair with a plain blanket or quilt.
If you want the bed to feel calm and layered rather than matched, a striped flat sheet with a plain fitted sheet is a simple way to get there.
Caring for Muslin Sheets
Muslin is easy to look after and needs no ironing. Wash your sheets alone the first time. Use a gentle cycle at 86°F (30°C) and tumble dry on low heat. If you are air drying, lay them flat rather than hanging them.
Do not use bleach and do not dry clean. Avoid washing sheets with jeans or anything that has small hooks, which can pull at the weave. Muslin becomes softer and more relaxed with each wash, so the sheets you have owned for a year will feel better than the ones you just opened.
Shop Muslin Bed Sheets
- Shop Muslin Bed Sheets
- Shop the Organic Muslin Fitted Sheet
- Shop Organic Muslin Blankets
- Shop Muslin Duvet Covers
Read Next
If you sleep warm and want the full sheet setup explained, read Best Bed Sheets for Hot Sleepers.
For a complete summer bed rather than just the sheet layer, read Lightweight Summer Bedding Guide for Hot Sleepers.
The Bottom Line
A fitted sheet is the one piece you cannot do without, because it creates the surface you sleep on. A flat sheet is optional, but it gives you a light top layer for warm nights and keeps heavier bedding cleaner.
If you are building a bed from scratch, start with a breathable fitted sheet, add a flat sheet if you sleep warm or want the flexibility, and layer a blanket or quilt above them as the season changes. Naturloom muslin sheets are made from organic Turkish cotton and ship from our family business in Florida.
Frequently Asked Questions
What is the difference between a flat sheet and a fitted sheet?
A fitted sheet has elastic edges and wraps around the mattress to create the surface you sleep on. A flat sheet is a plain rectangle with no elastic that lies over you, between your body and a blanket or duvet.
Do you really need a flat sheet?
No, it is optional. Many people use a duvet cover directly and wash it more often. A flat sheet is worth having if you sleep warm, want a light layer for hot nights, or prefer to wash heavier bedding less frequently.
Can you sleep with only a flat sheet in summer?
Yes. On warm nights a flat sheet over a fitted sheet is often enough. If the room cools before morning, a muslin blanket at the foot of the bed gives you something to pull up without changing the whole setup.
How do I know what size fitted sheet to buy?
Measure your mattress depth as well as its width and length, since deep mattresses need a deeper sheet to stay on the corners. Naturloom sheets fit standard US sizes and custom sizes are available for mattresses outside those measurements.
Are muslin sheets good for hot sleepers?
Muslin has an open weave that lets air move through the fabric rather than holding it against the skin, which is why it is often chosen for warm bedrooms and summer bedding. It is also lightweight, so it does not add weight to the bed.