How to Measure Your Bed for a Flat Sheet or Valance

You've measured the mattress, ordered what looked right, and the sheet arrived either swimming loose at the corners or too tight to tuck properly. Bed linen sizing sounds like it should be obvious — it isn't, because "double" and "king" mean slightly different things depending on who's selling it, and a flat sheet that's the wrong size doesn't fail gracefully. It just looks wrong on the bed, every single night, until you replace it.

Quick answer: A flat sheet needs to be roughly 30-40cm larger than your mattress on each side to allow for tucking. A valance needs matching entirely on drop length and base coverage, not mattress size — the two measurements aren't related, which is the mistake most buyers make.

What size flat sheet do I need?

A flat sheet needs to cover the mattress with enough overhang to tuck under on both sides and the foot end. A standard UK double mattress is 135 x 190cm, so a double flat sheet at 230 x 265cm gives tucking allowance without being so oversized it bunches.

Bed size	Mattress (approx)	Flat sheet size
Single	90 x 190cm	175 x 260cm
Double	135 x 190cm	230 x 265cm
King	150 x 200cm	275 x 275cm
Super King	180 x 200cm	305 x 275cm

If your flat sheet is sized closer to the mattress dimensions than this, it's not going to tuck — it'll sit flat on top and slip within a night.

What's the difference between a valance sheet and a base valance?

A valance doesn't cover the mattress at all — it covers the bed base and the visible gap underneath. A valance sheet has a fitted top panel that sits under the mattress plus a skirt that drops to the floor, covering both the base and the space beneath it. A base valance is just the skirt on a fitted band, designed to sit under the mattress alone. If your bed frame already has drawers or a solid base you don't need hidden, a base valance is the simpler and cheaper option. If there's genuinely nothing under there you want on show, go with the full valance sheet.

How do I measure the drop length?

Standard drop is around 40cm from the top of the base to the floor — right for most divan and standard bed frames. If your bed sits higher (hotel-style frames, older divans, beds with risers) the standard drop will look short and expose the frame underneath. Measure from where the mattress sits to the floor before ordering, not the frame height alone, because the mattress adds height you need to account for.

How deep does my fitted sheet need to be?

Depth refers to how far down the elasticated pocket reaches — standard is around 25-30cm (10-12 inches), extra-deep options go up to 40cm (16 inches) for pillow-top or layered mattresses. If your mattress plus topper is deeper than your fitted sheet's pocket, the corners will pop off within days regardless of how good the fabric is.

If you're ordering for more than one bed size across a property — student accommodation, holiday lets, or a small hotel — measure one of each bed type properly before ordering the full run rather than assuming standard sizing applies across the board. Call 01204 896528 if you want to talk through an unusual bed frame or mattress depth before you commit to a bulk order.

Once you've got sizing sorted, it's worth checking the thread count claims on whatever you're buying too — does a higher thread count actually mean better bedding? covers what the number actually tells you. 

Common questions

What size flat sheet do I need for a UK double bed? 

A standard UK double mattress is 135 x 190cm — a double flat sheet at 230 x 265cm gives enough overhang to tuck properly on all sides.

What's the difference between a valance sheet and a base valance? 

A valance sheet has a fitted top panel that sits under the mattress with a skirt to the floor. A base valance is just the skirt, designed to sit under the mattress alone.

How do I measure fitted sheet depth? 

Measure from the top of the mattress to the bottom, including any topper. Standard depth is 25-30cm; extra-deep options go up to 40cm.

Will a standard drop valance fit a high bed frame? 

Not always. Standard drop is around 40cm — measure from where the mattress sits to the floor before ordering if your frame is higher than average.

Can I use a flat sheet instead of a fitted sheet? 

Yes, some prefer this for ease of laundering, but it needs sizing larger than the fitted equivalent to allow for tucking, and it won't stay as secure overnight.

Do hotel beds use different sizing to home beds? 

Not usually in dimension, but hotel bed linen is typically a heavier, more wash-durable fabric — see the hotel bedding range if you're buying for guest rooms.

Browse wholesale flat sheets for the full size and fabric range, or valance sheets and base valances to check drop length and style before ordering.