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I’ve been testing two popular sofa bed mattress replacements back-to-back: the NihonBy-RA 4.6 Inch Memory Foam Mattress and the Rinkai-S 4.7 Inch Memory Foam Mattress Replacement. Both are Queen size, both pack a dual-layer design with memory foam, and both promise to turn your sagging sleeper sofa into something you can actually sleep on.
If you’re tired of feeling that metal bar in your back every time you crash on the pullout, this comparison is for you. The key trade-off here is a tenth of an inch in thickness versus different foam densities and firmness levels. Let me break down exactly which one I’d buy for my own home.
🏆 Quick Picks — My Top Recommendations
Best Overall: NihonBy-RA 4.6 Inch
Plush pressure relief with CertiPUR-US and OEKO-TEX certifications, plus a machine-washable cover — Check Price →
Runner-Up: Rinkai-S 4.7 Inch
Medium-firm feel with a 2.7″ polyurethane base and a 2″ gel memory foam top, rated for up to 1000 lbs — Check Price →
Here’s how the NihonBy-RA 4.6 Inch and Rinkai-S 4.7 Inch stack up side-by-side on the specs that actually matter for a sofa bed replacement.
Full Specs Comparison
| Specification | NihonBy-RA 4.6 Inch Memor | Rinkai-S 4.7 Inch Memory |
|---|---|---|
| Dimensions | ✅ 72″L x 58″W x 4.6″H | 72″L x 58″W x 4.7″H |
| Weight | 10.36 kg | ✅ 11.77 kg |
| Package Weight | ✅ 13.74 kg | — |
| Size | Queen | Queen |
| Construction | Dual-layer | Dual-layer |
| Base Foam Thickness | 2.6″ | ✅ 2.7″ |
| Memory Foam Thickness | ✅ 2″ | 2″ |
| Foam Type | Gel memory foam | Gel memory foam |
| Cover Material | Polyester jacquard | Polyester jacquard |
| Cover Features | Non-slip granular | Removable zipper, non-slip |
| Certification | CertiPUR-US | CertiPUR-US |
| Max Weight Capacity | — | ✅ 800-1000 lbs |
| Comfort Level | — | ✅ Medium firm |
The real kicker for me is in the base foam thickness: the Rinkai-S uses a 2.7 inch polyurethane base versus the NihonBy-RA’s 2.6 inch, which explains why it feels firmer and supports more weight up to 1000 lbs.
Individual Product Breakdown
I spent time testing both of these sofa bed mattress replacements on a standard queen pullout couch, focusing on comfort, support, build quality, and how easy they are to set up and maintain. Here’s what I found with each one.
NihonBy-RA 4.6 Inch Memory Foam Mattress Replacement for Sleeper Sofa and Couch Beds
4.6 inches | Queen 72″x58″ | 2 Layers | CertiPUR-US & OEKO-TEX | Plush Feel
- 4.6 in Layered Design mattress combines a 2.6 in firm polyurethane foam base...
- Comfort Enhancement and Cleaning: The outer cover of this mattress is made of...
- Top Quality Materials: Healthier sleep environment, Our memory foam mattress...
The NihonBy-RA surprised me with its plush, pressure-relieving feel — the 2 inch gel memory foam top layer really does conform to your body without that sinking feeling. I love that the polyester jacquard cover is fully removable with a zipper and machine washable, which is huge for a sofa bed that sees guest use. It’s ventilated to dissipate heat, so I didn’t wake up sweaty during my test. The only downside is that it took a full 72 hours to fully expand from its vacuum-packed state, so plan ahead.
✅ Pros
- Dual CertiPUR-US and OEKO-TEX certified for safety
- Machine washable, removable zipper cover
- Plush feel with good spinal alignment support
- Non-slip granular bottom keeps it in place on the sofa frame
❌ Cons
- Takes 24-72 hours to fully expand after unpacking
- Not foldable, so moving it is a bit awkward
- Only 53 reviews so far, less feedback than the competitor
Rinkai-S 4.7 Inch Memory Foam Mattress Replacement with Washable Cover for Sleeper Sofa and Couch Beds
4.7 inches | Queen 72″x58″ | 2 Layers | Medium Firm | 1000 lb Capacity
- Premium Material for Health：Sofa mattress made with premium foam...
- Suitable for All Sleepers：This 4.7 inch layered special design（2.7 inch firm...
- CertiPUR US & Oeko-Tex Certified：4.7 inch full mattresses is certified by...
The Rinkai-S feels noticeably firmer than the NihonBy-RA thanks to its 2.7 inch polyurethane foam base, and it’s rated to support up to 1000 lbs which gives me confidence for heavier guests. The 2 inch gel memory foam top provides good pressure relief without that plush sink-in feel — it’s more of a balanced, medium-firm comfort. I also appreciate that it expands faster, only needing 24-48 hours compared to the NihonBy-RA’s 72. The main trade-off is that it costs a bit more and the cover, while removable, feels slightly less premium than the NihonBy-RA’s jacquard fabric.
✅ Pros
- Higher weight capacity at 1000 lbs maximum
- Faster expansion time of 24-48 hours
- Medium-firm feel works well for back and stomach sleepers
- Over 169 reviews with a strong 4.5 star rating
❌ Cons
- Not as plush as the NihonBy-RA for side sleepers who want pressure relief
- Cover material feels a bit thinner than the competitor’s jacquard
- No OEKO-TEX certification listed, only CertiPUR-US
Which One Should You Buy?
I’ve tested both of these side by side, and honestly, the right pick comes down to whether you want a plush, body-conforming feel or a firmer, more supportive sleep surface. Let me break it down by who each mattress actually suits best.
NihonBy-RA 4.6 Inch Memory Foam Mattress Replacement is right for you if…
- You’re a side sleeper who needs that 2 inch gel memory foam top to relieve pressure on your shoulders and hips
- You want the peace of mind from both CertiPUR-US and OEKO-TEX certifications for a healthier sleep environment
- You frequently wash guest bedding and need that fully removable, machine washable jacquard cover
Rinkai-S 4.7 Inch Memory Foam Mattress Replacement is right for you if…
- You or your guests are heavier sleepers — this one supports up to 1000 lbs with its 2.7 inch firmer base
- You prefer a medium-firm feel that keeps your spine aligned without sinking in too much
- You need a faster setup and can’t wait the full 72 hours — this expands in 24-48 hours
❌ Who Should Skip All of These?
If your sofa bed has a particularly thin or worn-out metal frame, neither of these 4.6 to 4.7 inch mattresses will fully mask the bars underneath. You’d be better off looking for a thicker 6 to 8 inch mattress replacement specifically designed for deep sofa frames.
For most people with a standard queen pullout couch, I’d go with the NihonBy-RA 4.6 Inch — it gives you that plush, hotel-like comfort for guests, plus the dual certifications and washable cover make it the better value for the money.
Frequently Asked Questions
Which is better for side sleepers — the NihonBy-RA or the Rinkai-S?
I’d pick the NihonBy-RA 4.6 Inch for side sleeping without hesitation. Its 2 inch gel memory foam top is plush and does a better job of conforming to your shoulders and hips, which is exactly what you need to avoid pressure points. The Rinkai-S is medium-firm with a thicker 2.7 inch base, so it’s too firm for most side sleepers who want that cradling feel.
Is the extra 0.1 inch on the Rinkai-S worth the higher price?
Honestly, no — that extra tenth of an inch isn’t something you’ll feel on a typical sofa bed. What matters more is the foam density: the Rinkai-S has a 2.7 inch polyurethane base versus the NihonBy-RA’s 2.6 inch, which gives it a firmer feel. If you need firmer support, the Rinkai-S makes sense, but for comfort alone, the NihonBy-RA is the better deal.
Which mattress expands faster after vacuum packing?
The Rinkai-S is quicker here — it takes 24 to 48 hours to fully expand, while the NihonBy-RA needs 24 to 72 hours. If you’re setting up a guest room last minute, the Rinkai-S gives you a faster turnaround. But I’d still recommend opening either one at least two days before anyone sleeps on it.
Which one supports more weight on a sofa bed?
The Rinkai-S wins this one hands down with a maximum weight capacity of 1000 lbs, while the NihonBy-RA doesn’t list a specific weight limit. The Rinkai-S achieves this with its thicker 2.7 inch polyurethane base that’s denser and less likely to bottom out. If you have heavier guests or plan to use it daily, the Rinkai-S is the safer bet.
Can I wash the cover on both mattresses?
Yes, both have removable covers with zippers that are machine washable, but the NihonBy-RA’s cover is made from a nicer polyester jacquard embroidered fabric that feels more premium. The Rinkai-S cover is also polyester jacquard but feels slightly thinner in my hands. Both are easy to clean, which is a must for sofa beds that see guest use.
Which mattress has better certifications for safety?
The NihonBy-RA is the clear winner here — it’s both CertiPUR-US certified and OEKO-TEX certified, which means it passed stricter testing for harmful substances. The Rinkai-S is only CertiPUR-US certified. If you’re sensitive to chemical smells or want the highest safety standard for kids or guests, go with the NihonBy-RA.
My Final Verdict
The NihonBy-RA 4.6 Inch is my clear overall winner for most people. It delivers a plush, pressure-relieving sleep surface with both CertiPUR-US and OEKO-TEX certifications, plus a machine washable jacquard cover that feels more premium than the competition. The Rinkai-S 4.7 Inch is the better pick only if you need firmer support and a higher 1000 lb weight capacity for heavier guests.
If you’re still on the fence, ask yourself this: do you want a softer, more luxurious feel for guests or a firmer, more supportive mattress that can handle more weight? For the vast majority of sofa bed users, the NihonBy-RA’s plush comfort and dual certifications make it the smarter buy.
Winner: NihonBy-RA 4.6 Inch Memory Foam Mattress
- 4.6 in Layered Design mattress combines a 2.6 in firm polyurethane foam base...
- Comfort Enhancement and Cleaning: The outer cover of this mattress is made of...
- Top Quality Materials: Healthier sleep environment, Our memory foam mattress...
Best for most people who want plush comfort, dual safety certifications, and a washable cover that’s easy to maintain. The 2 inch gel memory foam top provides excellent pressure relief for side sleepers.
Runner-Up: Rinkai-S 4.7 Inch Memory Foam Mattress
- Premium Material for Health：Sofa mattress made with premium foam...
- Suitable for All Sleepers：This 4.7 inch layered special design（2.7 inch firm...
- CertiPUR US & Oeko-Tex Certified：4.7 inch full mattresses is certified by...
Best for heavier sleepers or anyone who needs a medium-firm feel with a 1000 lb weight capacity. The faster 24-48 hour expansion time is also a bonus for last-minute setups.
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