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The NihonBy-RA 4.6 Inch is the better pick for a queen sofa mattress if you want a plush, pressure-relieving feel because its 2 inch gel memory foam top layer is dual CertiPUR-US and OEKO-TEX certified, while the Rinkai-S 4.7 Inch suits heavier sleepers with its 1000 lb weight capacity. The thickness gap is only 0.1 inch — 4.6 versus 4.7 — and both share the same Queen 72″x58″ footprint with 2 layers.
- Choose NihonBy-RA 4.6 Inch if you sleep on your side and want a plush surface with dual CertiPUR-US and OEKO-TEX certification — it has a machine washable, removable zippered jacquard cover.
- Choose Rinkai-S 4.7 Inch if you need a medium-firm feel with a 1000 lb maximum weight capacity — it fully expands in 24-48 hours versus the NihonBy-RA’s 24-72 hours.
I compared these two on thickness and layer build, firmness and weight capacity, and certification and cover care. Everything below comes from the listed specifications for each mattress, not from a hands-on test.
🏆 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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