Choosing the right bed size is imperative.
Make sure you check the measurements before you purchase any bed, whether it is a single bed or a super king-size bed.

Choosing the right size bed.
Bed size can have a major impact on your sleep quality and bedroom style.
The most important thing is to be comfortable and stretch out, roll around, and starfish in comfort.
If you’re buying a young child’s bed, remember they’ll need room to grow.
The wrong size bed can affect a room's design in terms of style.
A bed that is too small will look out of place. It needs to be just the right size.

 

Will it fit? That's the big question.

Here are a few things you should consider before buying. 
Check and double-check the dimensions of the bed.
It is common for bed frames to have larger external dimensions than their mattresses.
Depending on the size of the headboard and footboard, the overall footprint can vary significantly for some beds, such as sleigh beds.
When it comes to simpler-styled beds, the mattress may extend to the foot end of the bed.

Top tips: 

If you are tall, remember that a mattress for double beds is only 190cm (6”3”) in length whilst king-size or super king mattresses are  200cm (or 6”6”) in length. So, a bed with a low foot end may be best.
Check the space of your room.
Planning your room layout should include things like skirting boards and door frames.
In addition, you should consider where the rest of your bedroom furniture will go and make sure you have enough space to access drawers and cupboards.