Selecting the right cot mattress is crucial for ensuring your baby sleeps safely and soundly. Whether you are preparing the nursery before your little one arrives or transitioning them to their own sleeping space around six months, the mattress you choose must meet key safety and comfort standards. Cot mattresses come in two standard sizes: a classic cot size measuring 120cm by 60cm and a larger cot bed size of 140cm by 70cm. Proper fit is vital for safety, and experts at The Lullaby Trust recommend a firm, flat mattress that fits snugly with no gaps larger than 1cm. While a soft, cloud-like surface may seem appealing, babies require a surprisingly firm surface to move easily and stay cool. The mattress should be firm enough that your baby's head does not sink in more than a few millimetres. Additionally, a waterproof mattress or fitted cover is recommended to prevent bacterial buildup and simplify cleaning.
How We Tested
Over the course of a month, we tested a variety of mattresses in our Coxley cot bed from Mamas & Papas. Our young tester participated in both naps and overnight sleeping, while we evaluated each mattress for firmness, fit, breathability, and practicality, including care, maintenance, and price. All mattresses complied with British Standard BS 1877-10:2011+A1:2012 and consisted of foam fibre, pocket springs, or natural fibres such as coconut coir. Each mattress was available in both cot and cot bed sizes.
Our Top Picks
1. Best Overall: Mother&Baby Pure Gold Anti-Allergy Coir Pocket Sprung Cot Bed Mattress
Type: Pocket-sprung
Why we love it: Dual-sided, exceptional allergy protection, coir layer, machine washable
Price: £130
This mattress impressed us from the moment we touched its super-soft cover. The natural coconut coir layer atop a pocket sprung core provides a firm, safe surface. Tencel fibres and Purotex anti-allergy properties reduce house dust mite allergens by 93.7%, cat hair allergens by 92.8%, and dog hair allergens by 66.7%. It is dual-sided with stitched labels indicating the firmer baby side and slightly softer toddler side. The waterproof membrane sits under a machine-washable cover, and our baby tester slept contentedly.
2. Best Budget Buy: Mamas & Papas Essential Fibre Cotbed Mattress
Type: Fibre core
Why we love it: Value for money, machine washable
Take note: Small zip section, could be thicker
Price: £49
Despite the low price, this Mamas & Papas mattress impressed us with its firmness. It is foam-free, can be flipped and rotated for maximum support, and has a water-repellent cover. The cover is removable and machine washable, though the zipped section at the bottom makes reinsertion a bit fiddly. It may be slightly shy of the standard 10cm depth, but it fit our cot bed perfectly and offered quality comparable to more premium options.
3. Best Dual-Sided Option: Snüz Surface Duo Dual Sided Cot Bed Mattress
Type: Pocket sprung
Why we love it: Dual-sided, machine washable cover, waterproof layer
Price: £120
Arriving vacuum rolled, this mattress features a pocket sprung core with a firm foam layer for the first 12 months. After that, you unzip and flip the internals for medium-firm support up to four years. It includes an anti-dust mite barrier, a waterproof membrane, and a machine-washable cover. The 3D breathable mesh cover kept our tester cool even during a heatwave.
4. Best for Firm Support: Silentnight Safe Nights Snuggle Breathable Mattress
Type: Foam
Why we love it: Super firm, machine washable cover, foam and FR chemical treatment free
Take note: No waterproof cover
Price: £79
This mid-range mattress from Silentnight was one of the firmest we tested. Its polyester inner is free of foam and fire retardant chemicals. The soft cloud cover can be zipped off and washed, but you will need a separate waterproof cover. Our tester enjoyed restful sleeps and good breathability.
5. Best for Natural Materials: Naturalmat The Coco Mat
Type: Coir
Why we love it: Five-year guarantee, natural materials, handmade in Devon
Take note: No waterproof cover
Price: £250
Handmade in Devon, this mattress features two wool layers from Soil Association-certified organic farms and a coir core from the world's only certified organic coconut plantation in Sri Lanka. The quilted wool-cotton cover is naturally fireproof. It is bedbug and dust-mite resistant, self-ventilating, and firm. It is the most expensive option and requires a separate waterproof cover.
6. Best for Heat Regulating: Baby Elegance Cot Bed Mattress
Type: Fibre pads
Why we love it: Machine washable cover, airflow technology
Take note: Tiny zipper takes getting used to
Price: £68
This mattress fits cot beds perfectly and uses Coolmax technology to optimise airflow. While we could not verify improved temperature regulation, our tester experienced no clamminess during hot naps. The cover is machine washable, though the tiny zipper is tricky. It is lightweight but standard 10cm depth, with anti-allergy fibre pads for a hypoallergenic sleep space.
7. Best for Older Babies and Toddlers: The Tiny Bed Company Tiny Dreamer Deluxe Organic Coconut and Pocket Sprung Cot Bed Mattress
Type: Coir and pocket sprung
Why we love it: Dual-sided, made in England, coir layer, machine washable
Take note: No waterproof cover
Price: £190
Handmade in England in small batches, this is the thickest mattress we tested. The top side features a soft honeycomb fabric with organic coconut coir, making it less firm and ideal for older babies and toddlers. The bottom side is firmer with a mesh cover for better airflow. The cover is machine washable, but a separate waterproof cover is needed. A build-your-own service is available for custom fit.
8. Best for Asthmatic Babies: ClevaMama Anti-Allergy Cot Bed Mattress
Type: Foam
Why we love it: Waterproof protection, certified asthma and allergy friendly, value for money
Take note: Cannot use immediately, light smell when unboxing
Price: £75
This mattress-in-a-box needs 48 hours to air out and unroll fully. The machine-washable outer cover offers 100% waterproof protection and keeps out bugs and dust. It is certified asthma and allergy friendly by Allergy Standards Ltd and infused with anti-fungal and anti-mite treatments. It is lightweight, firm, and comfortable at a reasonable price.
9. Best Quality: The Little Green Sheep Twist Natural Cot Bed Mattress
Type: Coir and wool
Why we love it: Five-year guarantee, natural materials, optimum comfort, dual-sided
Take note: Expensive, no removable cover
Price: £219
This is the heaviest mattress we tested due to its natural materials: a supportive natural latex, coconut husk fibres, and a wool layer that regulates temperature and resists bacteria and dust mites. It is dual-sided with a firm baby side for the first year and a spongier toddler side. The cover is not removable, so a waterproof protector is required. Our baby slept contentedly on this clean, comfy, and safe mattress.
10. Best for Travel: Ickle Bubba Fibre Cot Mattress
Type: Fibre core
Why we love it: Budget buy, machine washable, waterproof sleeve
Take note: No soft covering
Price: £69
This is the thinnest and lightest mattress we tested at 8cm depth, but it offers a firm sleeping surface. The fibre core is breathable and water-resistant, with a waterproof sleeve. The machine-washable cover is hypoallergenic. While the cover lacks a soft finish, a fitted sheet adds comfort. Its lightweight nature makes it ideal for travel.
11. Best Midrange Buy: CuddleCo Fibre Core Cot Bed Mattress with 2 in 1 Cover
Type: Bamboo fibre core
Why we love it: Waterproof layer, made in the UK, value for money
Take note: On the thin side
Price: £59
This affordable mattress offers a bamboo fibre core that is firm, hypoallergenic, and temperature regulating. It has a waterproof layer, though an additional cover is recommended for extra protection. The cover is easy to remove with a long side zip and is machine washable. It is slightly thinner than standard at just over 8cm, but comfort and support are not compromised.
12. Best for Breathability: Purflo Breathable Cot Bed Mattress
Type: Fibre padding
Why we love it: Fully machine washable, portable, fully air permeable
Take note: Requires assembly, expensive
Price: £139
Developed with a neonatologist and paediatric sleep doctor, this mattress requires about ten minutes to assemble the frame and mesh sleep surface. The cover is completely removable and washable. Its hollow core offers full breathability year-round, and it is remarkably supportive. It uses Amicor fibre padding, approved by Allergy UK, to reduce dust mites and allergies. It comes with a travel bag for portability.
13. Best for Snug Comfort: Silentnight Safe Nights Twinkle Breathable Mattress
Type: Pocket sprung
Why we love it: Comfortable quilted covering, hypoallergenic materials, breathable
Take note: No waterproofing, expensive
Price: £132
This premium mattress from Silentnight features individual pocket springs for support. The quilted terry towelling cover is comfortable, and the breathable polyester core regulates temperature. Hypoallergenic materials reduce allergies, and the mattress can be used while the cover is being washed, though it lacks the snuggly feel. There is no waterproofing, but it is a quality mattress suitable for the first four years.
Cot Mattress FAQs
What makes a good cot mattress?
A good cot mattress should be firm, flat, and fit snugly in the cot. It should carry the BSI number BS 1877-10:2011+A1:2012 to confirm safety standards. The mattress should be at least 8cm thick and ideally waterproof or have a waterproof cover. Foam mattresses are budget-friendly, spring mattresses offer long-lasting support, and coir provides breathability.
Can you use a second-hand cot mattress?
The Lullaby Trust advises using a new mattress for every baby. If a second-hand mattress is used, it must have always had waterproof protection, be in very good condition with no tears or rips, and be thoroughly cleaned.
The Verdict
While no mattress can guarantee perfect sleep, creating a safe and comfortable environment gives your baby the best chance. Our top pick, the Mother&Baby Pure Gold Anti-Allergy Coir Pocket Sprung Cot Bed Mattress, is a great all-rounder with dual-sided comfort, allergy and waterproof protection, and breathability at a reasonable price. For budget-conscious parents, the Mamas & Papas Essential Fibre Cotbed Mattress at under £50 impressed us with its quality.
