Quick answer

Measure your John Lewis mattress length and width first, then choose a fitted sheet that matches those exact dimensions and has deep enough pockets for the mattress height.

Why size accuracy matters for John Lewis mattresses

John Lewis cot and cot bed mattresses are made to specific dimensions, commonly 120x60cm for a standard cot and 140x70cm for a cot bed. Using a sheet that is too small can pop off during the night, while one that is too large may bunch up, creating a suffocation risk. Always check the dimensions on your mattress label or product page before buying.

Depth and pocket size: the overlooked factor

Even if the length and width match, the fitted sheet must have deep enough pockets to fit over the mattress thickness. Standard cot mattresses are typically 10-15cm deep, but some models are thicker. Look for sheets with elasticated edges that can accommodate your mattress depth. If you're unsure, measure the mattress height and compare with the sheet's stated pocket depth.

Steps to choose the right fitted sheet

  1. Measure your mattress: Use a tape measure to record the length, width, and height of your John Lewis mattress. Write these numbers down. Common sizes: 120x60cm for cot, 140x70cm for cot bed.
  2. Match the sheet dimensions: Look for a fitted sheet that lists the exact length and width of your mattress. Avoid 'one-size-fits-most' options unless they specify your exact measurements. A mismatch in length or width can cause the sheet to slip or bunch.
  3. Check the pocket depth: Compare the mattress height to the sheet's pocket depth. The sheet should have at least 2-3 cm of extra depth to stay secure. If the sheet is too shallow, it may pop off; if too deep, it may wrinkle underneath.
  4. Decide on pack quantity: A pack of 2 is enough if you wash frequently, but a pack of 4 provides backup for multiple changes between laundry days. Consider how often you want to do laundry and if you need extras for travel or daycare.
  5. Verify the material and care: Choose 100% cotton for breathability and easy washing. Check the care label to ensure it can handle frequent hot washes. Cotton sheets soften over time, but some blends may pill or shrink.

Product facts