How To Measure Mattress Size: A Simple Guide to Getting It Right

If you’re wondering how to measure mattress size—whether for a new bed frame, bedding, or a room layout—you’re in the right place. Mattress sizing can be confusing, and small mistakes can lead to ill-fitting sheets or furniture that doesn’t work in your space. This FAQ-style guide walks you through exactly how to measure mattress size correctly and what to keep in mind.

What Does “Mattress Size” Actually Mean?

When people talk about mattress size, they usually mean three measurements:

• Length (head to foot)
• Width (side to side)
• Height or thickness (top surface to bottom)

Standard size names like Twin, Full, Queen, and King refer mostly to length and width. Thickness can vary a lot, even within the same size, so it’s important to measure all three.

How To Measure Mattress Size Step by Step

1. What tools do I need?

You only need:

• A tape measure (flexible or retractable)
• A flat surface
• Something to write down your numbers

If possible, remove all bedding, toppers, and protectors before measuring.

2. How do I measure mattress width?

1. Place the mattress on a flat surface.
2. Measure from one side edge to the opposite side edge at the widest point.
3. Keep the tape measure straight and horizontal, not at an angle.
4. Note the measurement in inches or centimeters.

This gives you the width (for example, a typical Queen is around 60 inches wide).

3. How do I measure mattress length?

1. Measure from the head end to the foot end.
2. Again, keep the tape measure flat and straight.
3. Note this as the length.

Many standard mattresses are about 75–80 inches long, but this can vary.

4. How do I measure mattress height (thickness)?

1. Start from the bottom of the mattress (where it touches the foundation or floor).
2. Measure straight up to the highest point of the top surface.
3. If the surface is rounded or tufted, measure to the tallest point.

Mattress thickness often ranges from about 6 to over 14 inches. This matters especially for sheet pocket depth and bed frame fit.

How do I know which standard size my mattress is?

Once you know length and width, you can compare them to common mattress categories:

If your measurements are within about 1–2 inches of one of these pairs, your mattress likely falls into that size category. Slight variations are common due to manufacturing differences or rounded edges.

Why does measuring mattress size matter?

Accurate measurements help with:

• Choosing the right bed frame or base
• Ensuring sheets and mattress protectors fit properly
• Planning bedroom layout and space
• Matching a new mattress to an existing frame or headboard

Without knowing how to measure mattress size correctly, it’s easy to end up with gaps, overhang, or bedding that doesn’t stay in place.

Common Questions About Measuring Mattress Size

Should I measure the bed frame or the mattress?

Always measure the mattress itself when determining mattress size. Bed frames often have extra space or decorative elements that extend beyond the mattress and do not reflect the true sleep surface.

Do I include the mattress topper or pad?

If you’re buying sheets or mattress protectors, it can help to measure mattress + topper thickness together so you choose the correct pocket depth.

If you’re matching standard size names (Twin, Queen, etc.), measure just the mattress length and width.

What if my mattress doesn’t match any standard size exactly?

Some mattresses are custom or slightly non-standard. If your measurements don’t match typical sizes:

• Use your actual length, width, and height when choosing bedding.
• For frames, look for options that can accommodate your exact dimensions or offer some adjustability.

Even a few extra inches can affect fit and comfort, especially for tight-fitting sheets.

How precise do my measurements need to be?

Aim for measurements to the nearest half-inch. A small margin of error is usually fine, but more precise measurements are helpful if you’re dealing with tight spaces or custom products.

Tips for More Accurate Mattress Measurements

• Measure twice to confirm your numbers.
• Check from edge to edge, not from piping or seams alone.
• If your mattress has curved corners, measure at the widest and longest points.
• Avoid measuring while the mattress is bent, sagging, or partially off the frame.

✔️ Quick Mattress Takeaways

Key points to understand about How To Measure Mattress Size

• Use three measurements: width (side to side), length (head to foot), and height (thickness).
• Measure the mattress, not the frame, to determine true mattress size.
• Compare your length and width to common size ranges (Twin, Full, Queen, King, etc.) to identify standard sizing.
• Thickness matters for sheet fit and bed appearance; include toppers when choosing deep-pocket bedding.
• Allow for small variations in dimensions; focus on the closest standard size if you’re near common measurements.
• Re-measure if you’re unsure—accurate measurements reduce the chance of buying bedding or furniture that doesn’t fit.

Understanding how to measure mattress size gives you a clear starting point for everything from bedding to bedroom layout. With a tape measure and a few minutes of attention, you can confidently match your mattress to the right accessories and setup.