Many people today use mattresses that don’t follow standard sizing, especially in the US and European markets where custom-made mattresses are becoming more popular. But this also brings a challenge: how do you find the right size bed sheets for a mattress that isn’t standard?
Poorly fitted sheets can be frustrating. Fitted sheets may pop off the corners. Flat sheets may not cover the sides fully or can bunch up with too much excess fabric. This guide will help you choose the right custom size fitted sheet and custom size flat sheet based on your actual mattress dimensions, so your bed always looks clean and feels comfortable.
Fitted Sheet: Match Mattress Size and Add Extra Depth
A fitted sheet is designed to wrap around your mattress and stay securely in place.
- The length and width of the fitted sheet should match your mattress exactly.
- The depth (or mattress height) of the sheet should be 3 to 5 cm more than your actual mattress height. This extra fabric allows the sheet to tuck under the mattress securely and stay in place, even if your mattress is extra thick or has a topper.
Example:
If your mattress is 180 cm wide, 200 cm long, and 30 cm deep, your custom fitted sheet should be
180 cm x 200 cm x 33–35 cm (depth).
This ensures a snug fit that doesn’t pull loose overnight.
Flat Sheet: Use a Clear Formula for the Best Fit
A flat sheet should drape neatly over the sides and foot of your mattress. For custom sizes, we use the following formula to calculate the right dimensions:
Flat Sheet Length = Mattress Length + 2 × Mattress Depth − 10 cm
Flat Sheet Width = Mattress Width + 2 × Mattress Depth + 20 cm
This gives you a tailored fit that’s not too tight or too loose.
Why This Formula Works
Flat Sheet Width = Mattress Width + 2 × Depth + 20 cm
The goal is to have the flat sheet fully cover the sides of your mattress and drape beyond the edge a little for a clean look.
- The “2 × depth” part ensures the sheet can drop down on both sides of the mattress.
- The extra 20 cm means the sheet will hang an additional 10 cm below the mattress on each side.
This extra drop on both sides gives a soft, luxurious look and allows the sheet to be tucked under easily.
If you prefer less drape, you can reduce the extra length—for example, add just 10 cm total—but keep in mind that this value is split across both sides, so you need to calculate for both.
Flat Sheet Length = Mattress Length + 2 × Depth − 10 cm
This may look a bit unusual, but it’s based on how people typically make their beds.
- The foot of the bed usually needs more fabric to tuck in.
- The head of the bed, however, often sits against a wall or headboard, and doesn’t need extra length or draping.
That’s why we subtract 10 cm from the total length—it reduces excess fabric at the top, helps your sheet lay flatter, and makes the bed easier to manage.
Example Calculation
If your mattress measures:
Length: 213 cm
Width: 213 cm
Depth: 36 cm
Your flat sheet size would be:
Length = 213 + 2 × 36 − 10 = 275 cm
Width = 213 + 2 × 36 + 20 = 305 cm
So your custom size flat sheet should be 275 cm x 305 cm. This will give you a clean, balanced fit with a natural drape on all sides where it’s needed.
Why Custom Sizing Matters
The right sheet size improves both comfort and appearance. Sheets that are too tight can ride up; sheets that are too loose can bunch and look messy. When you use custom-sized sheets based on your actual mattress dimensions, you get:
- A better sleep experience
- A bed that looks well made
- Less hassle when making your bed
Let us know your mattress dimensions, and we’ll help you find the perfect fit.