Choosing between the TOTO Washlet KS6 and K300 is one of the most searched TOTO comparisons right now — and you deserve a straight answer on what’s actually different.
Both share TOTO’s signature PREMIST and EWATER+ hygiene technology, but the KS6 is the K300’s official replacement, and the upgrades go deeper than you might expect.
| Feature | TOTO Washlet KS6 (SW3946) | TOTO Washlet K300 (SW3036R) |
|---|---|---|
| Image |  |
 |
| 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 5-13/16″ |
| Water Heating | Instantaneous (unlimited) | Instantaneous (unlimited) |
| EWATER+ Wand Cleaning | Auto (inside & outside, before & after every use) + CLEAN RESIN | On-demand only |
| PREMIST | Yes | Yes |
| User Presets | 4 | 2 |
| Night Light | Yes | No |
| Seamless Seat Design | Yes | No |
| WASHLET+ Compatible | Yes | No |
| Buy Now |  |
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1. TOTO Washlet KS6 (SW3946#01)
The TOTO Washlet KS6 is the newest addition to TOTO’s online-exclusive lineup and the direct successor to the beloved K300.
It keeps everything that made the K300 great — instantaneous water heating, PREMIST, EWATER+, a slim wireless remote — and layers on a set of meaningful upgrades that push hygiene and comfort noticeably further.
If you’ve been comparing TOTO models across the lineup, you’ll find the KS6 slots in just below the TOTO Washlet S5 in feature density, but it brings a distinct design language and its own set of premium touches.
Features
- Instantaneous tankless water heating — unlimited warm water every time
- EWATER+ auto-wand cleaning inside and outside before and after every use
- CLEAN RESIN antimicrobial coating on the wand and seat surface
- PREMIST bowl misting before each use to prevent waste from sticking
- Seamless seat design with no gap between seat and cover
- 4 user memory presets on the wireless remote
- Built-in nightlight for low-light bathroom visits
- Adjustable spray position — front and rear
- WASHLET+ compatible for concealed cord and water line installation
- Warm air dryer with 3 temperature settings, SoftClose lid, auto deodorizer
Pros
- Significantly upgraded EWATER+ coverage versus the K300
- Seamless seat eliminates the hard-to-clean gap found on older models
- 4 user presets make it genuinely practical for multi-person households
- Nightlight is a quality-of-life upgrade that becomes indispensable fast
- WASHLET+ compatibility opens the door to a clean, cable-free installation
Cons
- Only available in Cotton White — no Sedona Beige option
- Elongated only — no round version available
- Higher price point than the K300 during the K300’s clearance phase
Check its current price on Amazon
2. TOTO Washlet K300 (SW3036R#01)
The TOTO Washlet K300 spent years as one of the most recommended mid-premium bidet seats on the market — and for good reason.
It brought together instantaneous water heating, PREMIST, EWATER+ wand cleaning, and a slim wireless remote at a price point that undercut TOTO’s flagship S-series models, making it the go-to recommendation in countless heated bidet seat roundups.
If you’re still researching the K300, it’s worth knowing that TOTO is actively phasing it out — the KS6 is its official replacement, with improvements across the board.
Features
- Instantaneous tankless water heating — endless warm water
- EWATER+ on-demand wand cleaning before and after use
- PREMIST bowl misting system before each use
- 5 spray settings including oscillating and pulsating modes
- 2 user memory presets on the slim wireless remote
- Adjustable heated seat, warm air dryer, built-in deodorizer
- SoftClose lid — no slammed seats
Pros
- TOTO’s proven EWATER+ hygiene technology at a potentially lower clearance price
- PREMIST is one of the most genuinely useful bidet features available
- Slim profile fits a wide range of elongated toilets
- Years of proven reliability and positive user reviews
Cons
- Being discontinued — limited long-term parts and support availability
- Only 2 user presets, which limits household flexibility
- No nightlight — a noticeable omission at this price tier
- No seamless seat design — the gap between seat and cover is harder to clean
- EWATER+ is on-demand only, not fully automatic like the KS6
- Not WASHLET+ compatible
Check its current price on Amazon
Hygiene Technology: Where They Really Differ
Both seats use TOTO’s PREMIST system, which mists the inside of the bowl with water before you sit down.
That single feature does more to reduce toilet cleaning effort than almost anything else on the market — and it’s one of the core reasons TOTO seats appear so often on the bidet toilet seat comparison chart.
Where they split decisively is EWATER+.
The K300 runs EWATER+ on-demand — the wand gets cleaned when you trigger it, but it’s not fully automatic.
The KS6 takes it further: EWATER+ cleans the wand automatically, inside and outside, before and after every single use — without you doing anything.
On top of that, the KS6’s wand and seat are coated in CLEAN RESIN, an antimicrobial material that actively resists grime and bacterial buildup between cleans.
For anyone who cares about genuine bathroom hygiene — and if you’re reading a bidet seat comparison guide, you probably do — the KS6’s hygiene system is the more complete package.
Winner: TOTO Washlet KS6
Comfort Features: A Closer Race Than You’d Expect
Both seats deliver the comfort basics you’d want from a TOTO WASHLET: unlimited warm water from an instantaneous heater, a SoftClose heated seat, oscillating and pulsating spray modes, and a warm air dryer with adjustable temperatures.
The KS6 adds two comfort improvements the K300 lacks.
First, the nightlight — a soft bowl illumination that guides you at night without blinding overhead lights.
It sounds minor until you’ve stumbled to the bathroom at 2am and immediately understood why it’s on every new TOTO model.
Second, adjustable spray position.
The KS6 lets you fine-tune the nozzle placement independently, giving you more precision than the K300’s fixed spray point.
This is particularly useful for users who’ve always wanted a cleaner, more targeted wash.
If comfort customization matters to you, you might also enjoy reading our comparison of the TOTO Washlet S5 vs Brondell Swash 1400 for context on how TOTO stacks up against other premium competitors.
Winner: TOTO Washlet KS6
Design and Build Quality
The K300 was already a well-built, slim seat by the standards of its time — at 5.25″ in rear height, it looked far more modern than TOTO’s older bulkier C-series models.
The KS6 refines that further.
Its seamless seat design eliminates the gap between seat body and cover — a notorious grime trap on older bidet seats that most people don’t notice until they have to clean around it.
The KS6 also introduces a sculpted, low-profile silhouette that blends into both modern and traditional bathrooms without drawing unnecessary attention.
If you’re pairing either seat with a TOTO WASHLET+ compatible toilet, only the KS6 supports concealed cord and water-line routing — giving you a genuinely clean, cable-free installation look.
For integrated toilet-and-bidet combinations worth considering alongside these seats, our highest-rated bidet toilet guide covers the full picture.
Winner: TOTO Washlet KS6
User Presets and Household Suitability
This one is simple and important.
The K300 gives you 2 user memory presets on its wireless remote.
The KS6 gives you 4.
For a single person or couple, 2 presets is perfectly fine.
For a family of three or four people who each have their preferred spray pressure, water temperature, and nozzle position, 4 presets is a meaningful practical upgrade — everyone gets their settings saved and ready without reprogramming the remote each time.
If multi-person household use is a priority in your buying decision, you can also read about how TOTO’s preset system compares to competitors in our best bidets for existing toilets guide.
Winner: TOTO Washlet KS6
Value and Long-Term Ownership
This is where the K300 makes its most compelling case — at least on paper.
Because the K300 is being discontinued, you may find it at clearance pricing that undercuts the KS6 significantly.
On pure sticker price, it could look like a great deal.
But there’s a real cost to buying a discontinued product: limited parts availability over time, no new production supporting warranty claims, and the risk that servicing becomes difficult if something goes wrong in year two or three.
TOTO products are built to last, and the K300 will likely perform reliably for many years — but buying it at end-of-life is a risk the KS6 doesn’t carry.
If budget is the primary concern, our best bidets under $500 guide covers strong alternatives across all brands at accessible price points.
Winner: TOTO Washlet KS6 (for long-term peace of mind)
Verdict — Which One Should You Buy?
The verdict here is clearer than most bidet comparisons.
The KS6 is a better product in every meaningful dimension — more automated hygiene, smarter design, more user presets, a nightlight, and WASHLET+ compatibility.
The K300 is not a bad bidet seat — it’s a great one.
But it’s being retired for a reason.
Buy the TOTO Washlet KS6 if… you want the current-generation TOTO experience with full manufacturer backing, automatic EWATER+ hygiene, 4 user presets, and a seat design built for the next decade.
Buy the TOTO Washlet K300 if… you find it at a deep clearance discount, you’re buying for a single-user bathroom, and you’re comfortable purchasing a product at end-of-life knowing parts may become harder to source over time.
For the vast majority of buyers, the KS6 is the right call.
If you’re also considering TOTO’s S-series lineup alongside the KS6, our breakdown of the TOTO S5 vs C5 gives useful context on where TOTO’s mid-range and premium tiers diverge.
FAQ
Is the TOTO K300 being discontinued?
Yes — TOTO is actively phasing out the K300 (SW3036R) and the KS6 (SW3946) is its official replacement.
The K300’s Amazon listing remains active during the transition period, but production has ended.
Once inventory sells through, it will no longer be available as a new product.
If you’re searching for the K300, the KS6 is the current model to buy — it retains everything the K300 did well and improves on it in nearly every area.
Will the TOTO KS6 fit the same toilets as the K300?
Both seats are designed for elongated toilets only — neither is available in a round version.
The KS6 requires a minimum 2″ clearance between the tank front face and the mounting holes, the same requirement as other current TOTO models like the S5 and S7.
If your K300 fit your toilet, the KS6 will almost certainly fit as well, though it’s always worth checking the TOTO WASHLET fit chart before ordering.
Note that the KS6 is WASHLET+ compatible, meaning it also works with TOTO WASHLET+ ready toilets for a concealed-cord installation — a feature the K300 lacked entirely.
What is the difference between the KS6 and the TOTO S5?
Both are current-generation TOTO seats with instantaneous water heating, EWATER+, PREMIST, and 4 user presets.
The KS6 has a slightly different design aesthetic — quieter and more sculpted — and is sold exclusively through online channels.
The S5 is TOTO’s mainstream mid-range flagship, the Wirecutter top pick for electric bidet seats, and slightly more widely available across retail channels.
Our full TOTO S5 comparison guide covers how the current S-series sits relative to earlier TOTO models if you want the broader picture.
Is the KS6 worth the extra cost over the K300?
In most cases, yes — particularly if you’re buying new.
The KS6 adds automatic EWATER+ (versus on-demand), CLEAN RESIN antimicrobial coating, a seamless seat, adjustable spray position, a nightlight, 4 user presets (versus 2), and WASHLET+ compatibility.
If the K300 is available at a significant clearance discount — say 30–40% or more below the KS6 — and you’re buying for a single-user bathroom with no WASHLET+ integration plans, the K300 remains a capable seat.
Otherwise, the KS6’s combination of upgraded hygiene and modern design makes it the better long-term investment.
For more perspective on where these models sit across the full TOTO lineup, the bidet toilet seat comparison chart gives you a comprehensive side-by-side view.
Conclusion
The TOTO Washlet KS6 vs K300 comparison ultimately tells the story of a product passing the baton to a better version of itself.
The K300 served buyers well for years — and at clearance pricing, it’s still a legitimate purchase for the right buyer.
But the KS6 is objectively more capable: fully automatic EWATER+ hygiene, CLEAN RESIN protection, 4 user presets, a nightlight, seamless seat construction, and WASHLET+ compatibility all represent genuine improvements over the outgoing model.
If you’re buying today, buy the KS6.
If you’re still exploring your options across brands and price points, the best bidets for existing toilets and the best bidet brands guide are excellent next reads.
