A baby mattress that is a few centimetres too small is not a small problem. A gap at the cot's edge is something safe-sleep guidance asks parents to avoid, and it is easy to get wrong, because cot sizes are less standard than the labels suggest.
Measuring takes five minutes, a tape measure and a notebook. This is how to do it properly.
In short
Measure the inside of the cot, in two or three places, and use the smallest reading. The mattress must fit snugly, with no gaps at the edges, and meet your cot manufacturer's requirements. Check the cot's manual, or ask its maker which mattress size it supports.
What you need
- A rigid tape measure. A cloth one sags and gives a false length.
- Your cot with the old mattress and any bedding removed.
- A pen. Write the numbers down and note the unit: inches or centimetres.
Step 1: Measure the inside, not the frame
Measure the interior of the cot, from the inside face of one side to the inside face of the other. The outside of the frame is larger and will mislead you.
- Length: from the inside of the head end to the inside of the foot end.
- Width: from the inside of one long side to the inside of the other.
Measure each in two or three places: both ends and the middle. Wood moves and cots flex, and the smallest measurement is the one that counts.
Step 2: Check the depth
Measure from the cot base to the top of the rail. Mattress thickness matters here because a thicker mattress raises your baby closer to the top of the side. Once your child can sit up or pull to stand, lower the base to its lowest position so the rail stays well above them. If your cot has adjustable base heights, check this with the mattress in place, not on its own.
Step 3: Look at the base
A mattress needs a flat, firm base to rest on. Check whether your cot has a slatted base, a solid board or a net, and that the slats are evenly spaced with none missing or loose. A firm mattress on an uneven base will not stay flat.
Step 4: Compare, and check the fit
The mattress must fit snugly, with no gaps at the edges, and meet your cot manufacturer's requirements. A gap is a place a baby can slide into. Check the cot's manual, or ask the maker which mattress size it supports. Not every bassinet or travel cot is designed for a replacement mattress, so do not assume that a size will work.
| Mattress | Size | Made for |
|---|---|---|
| Nurture | 52 x 28 x 4 in (about 132 x 71 x 10 cm) | Cots. Reversible: firm for infants, supportive for toddlers. |
| Nurture Mini | 36 x 24 x 2 in (about 91 x 61 x 5 cm) | Compatible compact cots. Single firm surface. |
If your interior measurements are close to one of these, check that the mattress would fit your cot snugly and that your cot's maker supports a replacement mattress of that size. If they fall between the two, or fit neither, do not stretch to make one work.
Common measuring mistakes
- Measuring the outside of the frame. It is always larger.
- Trusting the label. "Standard cot" is a description, not a measurement. Measure yours.
- Measuring once. Take two or three readings and use the smallest.
- Copying the old mattress. If it fits well now, its size is a useful clue, but measure the cot itself to be sure.
- Mixing units. Write inches or centimetres next to every number.
Questions parents ask
How do I measure a cot for a baby mattress?
Measure the inside of the cot, from the inside face of one side to the inside face of the other, for both length and width. Take two or three readings and use the smallest, then write down whether you used inches or centimetres.
How snugly should a mattress fit the cot?
It must fit snugly, with no gaps at the edges, and meet the cot manufacturer's requirements. A gap can let a baby slide into the space. If you are unsure, check the cot's manual or ask its maker.
What size is a standard cot mattress in India?
"Standard cot" is a description, not a measurement, and cot sizes are less standard than labels suggest, so measure yours. The Flexrest Nurture is 52 x 28 x 4 in (about 132 x 71 x 10 cm) for cots, and the Nurture Mini is 36 x 24 x 2 in (about 91 x 61 x 5 cm) for compatible compact cots. Check your cot maker's guidance on replacement mattresses before ordering.
What if my cot falls between two sizes?
Do not stretch to make a size work. Send us your interior length and width and we will help you compare them with our sizes, though your cot maker's guidance has the final word. Or use Find your size.
Does mattress thickness matter?
Yes. A thicker mattress raises your baby closer to the top of the cot side. Once your child can sit up or pull to stand, lower the base to its lowest position so the rail stays well above them, and check this with the mattress in place.
What should the base of the cot be like?
A flat, firm base with evenly spaced slats, none missing or loose. A firm mattress on an uneven base will not stay flat.
Still not sure?
Send us your interior length and width and we will tell you plainly whether either of our sizes fits. Write to us or message us on WhatsApp, or use Find your size to compare the two. For more on choosing, read how firm a baby mattress should be.