How Do I Choose the Best Mattress for My Bed?

You can choose the best mattress for your bed by evaluating your existing mattress and bed frame.

Here at Mattress Online, we understand that it's important to pair you with your perfect mattress. However, it's just as essential that the mattress is a good match for your bed.

In this guide we will take a look at how to choose a mattress for an existing bed. We will detail exactly how to measure your bed frame accurately and why, in some cases, it may be better to purchase a new bed frame for your mattress.

How to choose a mattress for your current bed

When you're choosing a new mattress for your current bed, you'll need to make sure that:

Your bed is a good match
Not every mattress will be compatible with every bed. If you have a bed frame with slats, check that the gaps between them are no greater than 8cm (3 inches). A gap wider than this may cause damage to your new mattress.
Your new mattress will fit your bed
You should ensure that your new mattress will fit your bed by measuring your bed. We recommend allowing a +/- one inch (2.54cm) tolerance in the stated width and length of your new mattress. This is because it's not always possible for a manufacturer to make a precise size, particularly for pocket sprung mattresses.

Consider whether you also need a new bed

If you are buying a mattress for an existing bed, you should also take into account the age of the current frame.

Has it seen better days?
Does it have slats and if so are they sagging, bent or broken?
If your bed is a divan, is the structural integrity of the base still there?

If you are unsure about any of the above, it may be better to purchase a new bed or divan base as well.

A black and silver Oban bed frame by Time Living in a light-coloured bedroom with stylish black interior accessories. — A mattress and bed frame should work together to provide you with the best support and comfort possible.

Buying a mattress and bed frame together means you can make sure you are getting a good fit. Many manufacturers actually offer divans and mattresses as a set, giving you one less thing to think about!

When pairing a new mattress with an old bed frame it is important to take care. If your bed frame shows any signs of damage such as broken slats or loose screws, this can damage your new mattress.

However, if your bed is relatively new or in very good condition, you should have no issues upgrading your mattress.

How to measure your bed for a new mattress

Before shopping for a new mattress, you should take the inside measurements of your bed.

Using a tape measure, measure the inside length of the bed frame where the mattress sits from top to bottom. Then measure the inside width of the bed frame, from side to side.
If you have a divan, take the measurements from the top where the mattress would sit flush with each of the divan sides.
Jot down these dimensions and use them for reference as you're shopping for a new mattress.
Make sure that your mattress isn't any larger than the measurements you have, though you can choose one which is around 1 inch (2-3cm) smaller.

A close shot of several measuring tapes laid down together. — It is essential to measure your bed before shopping for a new mattress.

Whilst shopping for a new mattress, the usual measurement categories are Single, Double, King and Superking as well as a handful of others. A breakdown of all the mattress sizes we offer is available below.

Mattress Size	Imperial	Metric
Single	3' x 6'3"	90cm x 190cm
Small Double	4' x 6'3"	120cm x 190cm
Double	4'6" x 6'3"	135cm x 190cm
King	5' x 6'6"	150cm x 200cm
Superking	6' x 6'6"	180cm x 200cm

For more sizes, please check our full Size Guide.

These measurements are based on the industry standard, but there are sometimes small differences between certain mattresses and manufacturers. When shopping for an existing bed it is always best to measure what you have and double-check.

Shopping for your mattress

Whilst shopping for your mattress, keep the measurements you have taken close to hand and compare with the measurements found on all our mattresses.

A person using a slim laptop on a clean white table. — On our site, it is so easy to compare not only measurements, but prices and specifications of all our mattresses.

You can choose a mattress than runs between 1 inch (2-3cm) smaller but certainly no larger than the measurements you have taken.

Once you find a mattress that seems like a good fit you can simply order, sit back and enjoy fast, free delivery!

When your mattress arrives, we do recommend testing the mattress for size on your bed before unwrapping.

Ensuring the perfect pairing between your bed and mattress is extremely important. It can provide you with years of good quality, supportive sleep. It really is time well invested!

Need a unique size?

Your bed may be a unique size and need a specific size of mattress. If you are struggling to find one on our site, please don't hesitate to get in touch and make use of our expertise. We are here to help!