It is 2 am. Your baby has just had one of those spectacular nappy incidents that somehow defies the laws of physics. You have changed the sheet, and there are no clean ones left.
So how many cot sheets do you actually need? The right number depends on how often you wash, whether the baby sleeps in more than one space, and how old they are.
The Short Answer
For the newborn stage (0-4 months), aim for 5-6 fitted cot or crib sheets. For older babies (4 months+), 3-4 is a comfortable minimum if you do laundry every 2-3 days.
What Affects How Many You Need
Laundry frequency
This is the biggest variable. If you do laundry daily, you can manage with 3 sheets. Every 2-3 days puts you at a minimum of 4-5. If you batch-wash weekly, 6-7 gives you a sensible buffer.
Number of sleep spaces
Babies who split their nights between a bedside crib and daytime naps in a Moses basket need sheets for both.
Baby's age
Newborns have significantly more accidents per week than a 9-month-old. In the early weeks, leaky nappies, posset, and occasional explosive incidents, you may need to change the sheet every day or two.
Season
Warmer months mean babies sweat more, particularly if they sleep in a warm room. You may find yourself washing sheets more often in summer.
Recommendation by Stage
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Newborn (0-4 months): 5-6 sheets
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4-8 months: 4-5 sheets
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8 months and over: 3-4 sheets
What to Look for When Buying Cot Sheets
Fit matters for safety
A fitted sheet that is too loose can come away from the corners of the mattress and create a loose fabric hazard. The Lullaby Trust recommends keeping the sleep space clear of loose bedding. Always buy sheets made for the specific mattress size you are using. Make sure to measure before buying rather than assuming standard sizing.
Material
100% cotton is the most breathable option and holds up well to repeated washing. Jersey cotton (stretchy) is especially easy to put on and off, which matters when you are doing a 4 am sheet change.
Easy fastenings
Elasticated corners that go all the way around the sheet, not just at the corners, stay on more securely. Look for deep-pocket sheets if your mattress is thicker than standard.
