Choosing between the TOTO WASHLET KS6 and S7A puts you at a genuine crossroads in the TOTO lineup — and the difference is bigger than you might think.
Before you spend a single dollar, this breakdown gives you the honest, side-by-side comparison you need to pick the right seat for your bathroom.
| Feature | TOTO WASHLET KS6 | TOTO WASHLET S7A |
|---|---|---|
| Image |  |
 |
| Model Number | SW3946#01 | SW4736AT40#01 |
| Dimensions (L x W x H) | 25-5/16″ x 15-1/4″ x 11-13/16″ | 20-7/8″ x 15-1/16″ x 4-1/16″ |
| Water Heating | Instantaneous (unlimited) | Instantaneous (unlimited) |
| EWATER+ Coverage | Wand only | Wand + bowl |
| Auto Open/Close Lid | No | Yes (motion sensor) |
| User Presets | 4 | 4 |
| Warranty | 1-year limited | 2-year limited |
| Buy Now |  |
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1. TOTO WASHLET KS6 (SW3946#01)
The KS6 is TOTO’s newest mid-tier WASHLET — a direct successor to the popular K300 — and it brings a sculpted, minimalist silhouette that fits naturally in both modern and traditional bathrooms.
If you want everything the K300 had plus EWATER+ wand cleaning, a seamless seat design that eliminates dirt-trapping gaps, and four user memory presets, the KS6 is the upgrade you’ve been waiting for.
Features
- Instantaneous tankless water heating for unlimited warm water
- Five spray settings: rear, soft rear, front, oscillating, pulsating
- PREMIST function mists the bowl before each use to reduce waste adhesion
- EWATER+ automatically cleans the wand inside and out before and after every use
- Heated SoftClose seat with five temperature levels
- Warm air dryer with adjustable temperature
- Built-in air deodorizer with automatic activation
- Soft nightlight for low-light bathroom visits
- Illuminated handheld/wall-mountable remote with 4 user memory presets
- WASHLET+ compatible for concealed hose/cord installation on select TOTO toilets
- Seamless seat design with CLEAN RESIN surface
- Elongated fit only; Cotton White
Pros
- Very strong feature set at a mid-tier price point
- Elegant low-profile design that blends into most bathrooms
- EWATER+ and PREMIST together provide serious passive hygiene
- Four user presets — unusually generous for this price tier
- Replaces the discontinued K300 with meaningful upgrades
Cons
- No auto open/close lid — you still need to lift and lower manually
- EWATER+ only covers the wand, not the bowl (unlike the S7/S7A)
- Only 1-year limited warranty — shorter than the S7A
- Elongated only; no round version available
Check its current price on Amazon
2. TOTO WASHLET S7A (SW4736AT40#01)
The S7A is TOTO’s current flagship bidet seat — the most feature-complete WASHLET in the lineup and the replacement for the beloved S550e.
What sets the S7A apart from its sibling the S7 is one genuinely life-changing addition: an automatic open/close lid with a motion sensor that opens the seat as you approach and closes it after you leave — no hands, no buttons, no effort.
Features
- Automatic open/close lid with motion sensor — hands-free, fully touchless
- Instantaneous tankless water heating for endless warm water
- Five spray settings: rear, soft rear, front, wide front, oscillating, pulsating
- AIR-IN WONDER WAVE technology aerates each water droplet for a softer, more comfortable spray
- EWATER+ cleans both the wand AND the toilet bowl after every use
- PREMIST pre-wets the bowl before each use to prevent waste adhesion
- Heated SoftClose seat with five temperature settings
- Warm air dryer with five temperature levels
- Power deodorizer with boost mode for especially strong odors
- Soft nightlight with scheduling and night mode
- Illuminated touch-button remote with 4 user memory presets
- Ultra-slim 4.1″ rear profile — one of the sleekest bidet seats available
- Auto-flush compatible with separately sold TOTO kit
- WASHLET+ compatible; works with standard and TOTO T20/T40 toilets
- Seamless seat with CLEAN RESIN surface; Cotton White or Sedona Beige
- 2-year limited warranty
Pros
- Auto open/close lid is a genuinely transformative convenience — especially for hygiene
- EWATER+ covers both the wand and the bowl — the most complete passive hygiene on the market
- AIR-IN WONDER WAVE makes the spray measurably more comfortable than standard aerated streams
- Ultra-slim 4.1″ profile creates an integrated, near-seamless look on the bowl
- Power deodorizer boost is a thoughtful real-world upgrade
- Auto-flush compatible for a fully touchless bathroom when paired with the right TOTO toilet
- 2-year warranty offers better long-term protection than the KS6
Cons
- Significantly higher price than the KS6 — the auto lid commands a real premium
- Auto-flush requires a separate kit and a compatible TOTO toilet
- Elongated only; no round bowl version
Check its current price on Amazon
Water Heating: Both Win Here — But One Does More With It
Both the KS6 and S7A use instantaneous tankless water heating, so neither seat ever runs cold mid-wash — a clear upgrade over older tank-heater models you may have read about in our best bidets for existing toilets guide.
The difference comes in how that water is delivered.
The S7A’s AIR-IN WONDER WAVE system infuses air into each droplet before it exits the nozzle, producing a softer, broader spray that many users find more comfortable and more effective than a conventional aerated stream.
The KS6’s spray is excellent — smooth, warm, and fully adjustable — but it lacks that aeration upgrade.
Winner: TOTO WASHLET S7A — same unlimited warm water, but meaningfully more refined delivery.
Hygiene Technology: This Is Where the Gap Opens Up
This is the most important category in this comparison, and it’s where the S7A justifies a significant portion of its premium.
Both seats use PREMIST to spray the bowl before you sit, which dramatically reduces waste adhesion and cuts your cleaning time substantially.
Both seats use EWATER+ — TOTO’s proprietary electrolyzed water system that converts tap water into a mild sterilizing compound — to clean the wand before and after every use.
But the S7A goes further: its EWATER+ also automatically mists the toilet bowl after every flush, keeping the bowl itself consistently cleaner without any scrubbing effort on your part.
The KS6’s EWATER+ stops at the wand.
This is not a minor distinction.
If you’ve ever opened your toilet lid mid-week and wondered how it got that way despite regular cleaning, you’ll understand immediately why bowl EWATER+ matters.
You can explore why this level of passive hygiene is so valued in our pros and cons of bidets breakdown.
Winner: TOTO WASHLET S7A — EWATER+ for both the wand and the bowl is a genuinely meaningful hygiene advantage.
Design and Profile: The S7A Is Visibly Slimmer
The KS6 has a refined, sculpted look that sits nicely on most elongated toilet bowls.
But the S7A’s 4.1-inch rear profile is in a different category entirely.
At that height, the S7A is one of the thinnest bidet seats available anywhere, and when paired with a TOTO WASHLET+ compatible toilet — which conceals the power cord and water supply hose inside the toilet’s base — the result looks nearly indistinguishable from a high-end integrated bidet toilet.
If bathroom aesthetics are important to you and you’ve been researching the difference between a bidet toilet vs a bidet seat, the S7A’s slim profile genuinely narrows that visual gap.
The KS6 is by no means bulky — it’s a modern, low-profile seat — but the S7A’s silhouette is in a class of its own.
Winner: TOTO WASHLET S7A — the 4.1″ rear height and contemporary lid design are in a different aesthetic league.
Convenience Features: Auto Lid Changes Everything
The KS6 comes with a soft-close lid, a SoftClose seat, and a handheld illuminated remote with four user memory presets.
That’s genuinely strong at its price tier — and it already puts the KS6 ahead of many competing seats covered in our bidet toilet seat comparison chart.
But the S7A adds automatic lid opening and closing via a motion sensor — and once you’ve used a bidet seat with this feature, going back feels almost unthinkable.
The lid opens as you walk toward the toilet and closes automatically after you step away.
It eliminates a touchpoint entirely, which matters for hygiene, and creates a genuinely spa-like experience that’s hard to put a price on.
The S7A also adds a power deodorizer boost mode, finer control over nightlight scheduling, and auto-flush compatibility for a fully touchless experience when installed with the optional TOTO kit.
Winner: TOTO WASHLET S7A — the auto lid alone is worth serious consideration.
Verdict: Which One Should You Buy?
Buy the TOTO WASHLET KS6 if… you want a premium TOTO WASHLET experience — unlimited warm water, EWATER+ wand cleaning, PREMIST, four user presets, and a sleek modern design — without paying the steep premium the S7A commands.
The KS6 is the natural successor to the K300, and it’s a genuinely excellent seat.
If your budget is the deciding factor, or if you simply don’t need bowl EWATER+ and an auto lid, the KS6 delivers real TOTO luxury at a more accessible price.
It’s also worth comparing it to the TOTO C5 vs S7 to see where the KS6 sits in the broader lineup.
Buy the TOTO WASHLET S7A if… you want the absolute best bidet seat TOTO makes, and you’re not willing to compromise on anything.
The auto open/close lid, EWATER+ bowl hygiene, AIR-IN WONDER WAVE spray, ultra-slim profile, power deodorizer boost, 2-year warranty, and auto-flush compatibility make the S7A the most refined WASHLET in existence.
If you’re building a luxury bathroom, upgrading from an older flagship like the discontinued S550e, or simply want the best and have the budget for it, the S7A is the answer — and our highest-rated bidet toilet guide can help you pair it with the right toilet.
FAQ
Is the TOTO KS6 a replacement for the K300?
Yes.
The KS6 (SW3946) is the direct successor to the K300 (SW3084/K300), which has been discontinued.
The KS6 brings meaningful upgrades: a seamless seat design that eliminates hard-to-clean gaps, updated CLEAN RESIN surfaces, and a refreshed sculpted silhouette — while retaining all the EWATER+ wand cleaning and PREMIST technology the K300 was known for.
If you loved your K300 and are looking for a like-for-like replacement, the KS6 is exactly what you want.
What is the difference between the TOTO S7 and S7A?
The S7 and S7A are functionally identical seats — same spray technology, same hygiene systems, same slim profile.
The one meaningful difference is that the S7A adds an automatic open/close lid with a motion sensor.
The lid opens as you approach and closes after you leave — no hands required.
If that touchless convenience matters to you (and for most people who experience it, it quickly becomes non-negotiable), the S7A is worth the step up from the S7.
You can also compare the TOTO S7A against the S5 to see where the upgrade makes sense.
Do both seats work on standard toilets, or do they require a TOTO toilet?
Both the KS6 and S7A are designed for standard elongated toilet bowls and will fit most standard two-piece and one-piece elongated toilets without any special hardware.
The important compatibility check is the “French curve” — if your toilet tank meets the bowl on a curved slope rather than at a flat 90-degree angle, neither seat may fit properly.
Both seats are also WASHLET+ compatible, meaning when used with a TOTO T20 or T40 WASHLET+ ready toilet, the power cord and water supply hose are routed inside the toilet base for a clean, cable-free installation.
Check TOTO’s official fit chart before purchasing if you have an unusual bowl shape.
Which seat is better for a family bathroom with multiple users?
Both seats offer four user memory presets — an unusually generous number that gives every member of a household their own saved spray settings.
That said, the S7A has a practical edge in a multi-user household: the auto open/close lid reduces the likelihood of anyone leaving the seat up, and the EWATER+ bowl misting keeps the toilet cleaner between uses without relying on any individual to do it.
For a family bathroom where hygiene habits vary, the S7A’s passive automation is genuinely useful — and for more buying context, our guide to the best bidets for home use covers multi-user considerations in detail.
Conclusion
The TOTO WASHLET KS6 and S7A both deliver TOTO’s signature build quality, unlimited warm water, PREMIST, and EWATER+ — but they serve clearly different buyers.
The KS6 is the right call if you want a premium WASHLET experience at a more accessible price, with a beautiful design and strong feature set that beats nearly everything else in its tier.
The S7A is the right call if you want the absolute best — bowl EWATER+, auto open/close lid, AIR-IN WONDER WAVE, 2-year warranty, and a 4.1″ ultra-slim profile that makes your toilet look like an integrated smart fixture.
Neither choice is wrong.
But the S7A’s advantages are real and tangible, not just marketing.
If you’re still weighing your options, our full bidet toilet seat comparison chart gives you a side-by-side look at the entire market, and our best bidet brands guide explains why TOTO consistently ranks at the top of it.
