RELEASED 2021.11REASSESSED 2026.08.07

HOBOT

HOBOT 388 Ultrasonic

Name: HOBOT 388 Ultrasonic
Brand: HOBOT

Ultrasonic misting plus systematic path coverage handles routine window cleaning without manual scrubbing within a pane. The constraint is placement: every window is a new setup, and the unit cannot transfer itself between panes.

Autonomy Ladder

Why Level II.

One five-rung scale, every category, from acting only on command to working unsupervised anywhere.

VGeneralized AutonomyAny task, any setting. No consumer robot has reached it.
IVEnvironmental AutonomyCopes with everyday clutter and frees itself, shown by independent testing.
IIIConditional AutonomyFinishes whole jobs in familiar spaces; struggles at the edges.
To reach Level IIIMost sessions finish without intervention. Rescue is occasional, not routine.
IIAssisted AutonomyThis robot

HOBOT 388 Ultrasonic runs preset routines on its own, and the owner is its recovery system.
What it does on its own
- Completes full-pane systematic coverage unattended after placement; no mid-window repositioning required (owner reports, manufacturer documentation).
- Ultrasonic nozzle nebulizes water into a 15 micrometer mist ahead of the pads; two microfiber-covered wheels turning at up to 70 rpm do the mechanical work (manufacturer documentation).
- Edge detection reverses at window frame boundaries without owner intervention (manufacturer documentation, demonstration coverage).
- Companion app on Android and iOS plus an included handheld remote handle start and mode selection (manufacturer documentation).
- Embedded UPS holds the unit in position on the glass with an audible alert for 20 minutes if mains power is interrupted (manufacturer documentation).
Why this level
- Systematic horizontal-stripe path coverage completes a full window pane without owner repositioning once the unit is placed and started, and edge detection handles boundary reversals without intervention.
- The operating domain ends at the pane: the owner carries the unit to each window, anchors the safety rope to an indoor fixture and starts the cycle again, so the machine does not carry the household task through end to end.
- Per-pane placement is the ceiling applied to every window robot classified in this database.
What holds it at Level II
- Inter-window transfer: Unit cannot navigate between window panes; owner must relocate after each pane (inherent form factor, owner reports).
- Surface dependency: Suction anchor requires smooth flat glass; any surface irregularity interrupts autonomous path coverage (manufacturer documentation).
- Pad saturation: Cleaning degradation on heavily-soiled consecutive panes requires mid-session pad swap and owner restart (owner reports).
- Setup per pane: Each window needs the unit carried over, the safety rope anchored indoors and the cycle started again (manufacturer documentation).
Autonomy dimension 64 / 100 · 7 sources reviewed
IManual AutomationOne action on command; no independent operation.

How we assign a level →

Behind the classification

Sources we reviewed.

Provisional7 sources reviewed

Enough has been reviewed to classify, but gaps remain across source types.

Sources reviewed

Manufacturer documentation3 sourcesReviewed

HOBOT 388 product page specifications, safety documentation, and companion app guide.

Longitudinal signal2 sourcesReviewed

Robovations dated log for this robot: 3 tracked entries spanning ~16 months.

Specification sources2 sourcesReviewed

Pages the published specifications were read from.

Monitoring record2 sourcesReviewed

Sources behind the tracker entries following this robot.

Also monitored, nothing listed yet

Press & video reviewsPending

Technology press coverage of HOBOT 388 at launch and category comparisons from home-tech publications.

Owner reportsOngoing

Consumer forum and retail review aggregates covering pad life, suction reliability, and app connectivity.

How we evaluate evidence →

Human Readiness

Ready Now.

One question: what does buying this robot today walk you into? The state is computed from the record, and recomputed daily.

Ready NowThis robot

HOBOT 388 Ultrasonic is on sale, assessed, and nothing on its record argues for waiting.
How this was derived
- Shipping past the first-90-day ownership window with a published assessment, no documented issues on record, and no announced successor.
Notes on the record
- Available direct from HOBOT and third-party retailers since late 2021 at $249–$299.
- Setup requires attaching a microfiber pad, anchoring the safety rope, and positioning the unit on glass.
- Ongoing effort is pad laundering after every use and periodic rope inspection.
On the record
- Shipping since November 2021 · 58 months on the market
- Retail listings on file: Amazon
- No current new-stock listing confirmed
- No successor announced
- 7 sources reviewed
What would move it
A documented problem, an announced successor, or a withdrawn listing moves it out; the rating recomputes daily.
New to MarketOn sale under 90 days; the ownership record is still forming.
WaitA successor is announced and has not shipped; re-read the decision when it arrives.
Known IssuesDocumented problems stand on the record; read the case before buying.

How we assess readiness →

Robovations Score

How this number was reached

70of 100

StrongAt or above 67% of the 436 robots we scoreand 95% of the 21 scored robot window cleaners

DeficientLimitedCapableStrongExemplary

Measured on 8 of the 9 inputs14% not counted

Our assessment did not establish an independent source for software stability on this machine, so that input is left out of the score rather than guessed at, and the rest re-weighted to fill the space. A gap in what we have been able to verify is not evidence against the robot. Where a whole pillar has nothing measured, we publish no number at all.

What moved itpoints gained or lost against a typical robot

Carried by

Field failure rate85+2.4
Consumables91+1.8
Support longevity73+1.1

Held back by

Routine maintenance34−4.0

Capability40% of the score67What it does without you.

Task completion16% of the score75

Evidence

Once placed, it covers the pane systematically and unattended at a published 4 minutes per square meter, reversing at frame boundaries without intervention, with water laid down as a 15 micrometer ultrasonic mist ahead of two microfiber wheels rather than run onto the glass. Two documented items put a human back in the run rather than only at the ends: a saturated pad streaks across consecutive heavily soiled panes and needs a mid-session swap and restart, and owner reports say heavily soiled glass may need a second pass with a fresh pad. It does not descend or return.

Coverage and navigation10% of the score70

Evidence

iTWire's hands-on review of the Hobot 388 reports that beyond the multi-storey case "it will clean all windows without any intervention. With a few caveats, of course", and robotobzor.ru's own bench and window test concludes "робот прошел все тесты" (the robot passed all tests) on small and medium windows, with automatic detection of the boundaries of the cleaning area. No source in the pool reports a missed region, but neither documents corner coverage, and one owner in robotobzor's comment thread reports streaks left behind.

Edge-case recovery10% of the score50

Evidence

iTWire cut the mains power deliberately mid run: "we had the Hobot operating and deliberately pulled the plug; it stopped moving and simply stayed where it was." It holds itself on the glass rather than falling, but it does not resume on its own, and iTWire adds that "the device should only be turned off from the physical switch as the suction motors will stop and it will fall off the window", so a human has to end and restart every interruption correctly.

Operating envelope4% of the score65

Evidence

robotobzor.ru's test finds it "в большей мере подходит для мойки пыльных окон" (better suited to dusty windows) and that on a greasy kitchen backsplash "не факт, что с первого раза это получится, или получится вообще" (it is not certain it will work on the first pass, or at all); the same test puts the working range at a 35 by 35 cm minimum pane and a maximum surface step of 1.5 mm, so heavily framed or beaded glass and heavy soiling both fall outside it.

Dependability40% of the score80Whether it keeps doing it.

Field failure rate16% of the score85

Evidence

Four and a half years in market since November 2021 with no documented safety recalls and owner forums reporting consistent suction motor performance across multi-year use, which is a mature record by this category's standards. The most common documented mode is seal loss on glass carrying a residue film, and the record is careful that this is a surface-condition issue rather than a mechanical regression. Evidence is consumer forum and retail review aggregates with no links on file, so the retail-review ceiling applies without binding.

Software stabilitynot countedno source verified33

Evidence

Robotobzor's R3 review states that updating the robot through the app, 'which guarantees the stability and relevance of the software', is among the app features that 'set it apart from the 368 and 388 models'; the same site's 388 review lists that robot's app functions as remote start, three cleaning modes and push notifications, with no firmware update among them. No update channel for the machine itself is documented, so the stored 33 stands.

Support longevity10% of the score73

Evidence

Four and a half years of continuous availability direct from HOBOT and third-party retailers, from a specialist manufacturer with a live product line above it, and a consumable channel with genuine redundancy: replacement pads are available from HOBOT and from third-party suppliers, so supply does not depend on one vendor. The record also documents owner-serviceable replacement guidance for the safety rope and the power cable. Held here because no support term, parts window or end-of-support date is published, and the model carries no update commitment of any kind.

Ownership burden20% of the score57What it asks of you.

Routine maintenance12% of the score34

Evidence

Two chores after every single use, and the second is load-bearing rather than cosmetic: the pad comes off to be rinsed and hung dry, and the suction ring is wiped to remove glass cleaner residue that degrades the seal over time, which is the same residue named as the machine's most common failure mode. Around them, a monthly safety rope fray inspection with replacement on any strand damage, a three to six month intake port brush and a mineral check on the pad contact surface, and an annual power cable sheath inspection. Per pane the owner carries the unit over, runs the cord and anchors the rope, plus mid-session pad swaps on soiled glass.

Consumables8% of the score91

Evidence

The best consumable position among the corded machines here. Pads are washable and reusable for 30 to 50 wash cycles rather than a wear item, and they are sourced from both HOBOT and third-party suppliers. HOBOT specifies its own detergent for the ultrasonic nozzle but states that pure water also works, so there is no proprietary metered supply to buy. Nothing else recurs on a schedule: rope and power cable are replaced on inspection, not on a calendar, and there is no filter cartridge and no subscription.

middle half of the databaseits medianthis robot

Reported, not scoredneither measures how well the robot works

Five-year cost$415

Inexpensive to own for a window cleaner, and the running cost is genuinely small rather than merely deferred. About 275 dollars at the middle of the 249 to 299 dollar range, plus roughly 75 dollars of replacement pads over five years, since the pads last 30 to 50 wash cycles and a household cleaning a few times a year will not exhaust many, about 40 dollars of detergent, which is optional because HOBOT states pure water works, and one safety rope replacement. No subscription and no metered supply.

Data postureLocal

Core function needs no account and no network.

What leaves the homeDocumented

The HOBOT 388 operates via a companion app with standard Wi-Fi connectivity. Basic control is available via onboard buttons with no network transmission. The companion app sends session commands to the device locally; manufacturer privacy documentation does not indicate cloud-based data collection from device operation. No documented history of third-party data sharing or security incidents.

On-device processingYes

Read the full methodology →

FIT CHECK

Will the HOBOT 388 Ultrasonic work on your windows?

Describe your windows using the controls. Each choice reads the spec sheet for you, flagging where the HOBOT 388 Ultrasonic is built for your space and where it isn’t.

Window style

Frame style

Building height

Power preference

See every window cleaner suited to these conditions

A classification of fit for the conditions you set, not a recommendation. Verdicts describe engineering design intent, not test results.

SPECIFICATION

The full spec sheet.

Priced below the category median, with every figure charted against the category below.

Dimensional drawing

Key specificationsManufacturer-published

Footprint: 5.83 × 11.61 in · 3.74 in tall
Weight: 2.02 lbs
Wi-Fi: Supported
Backup battery runtime: 20 min•
Power type: Mains-corded, 5 m cord•
Min pane size: 13 in•
Safety rope rating: 441 lb•

Where it lands · ranked across 27 robot window cleanersThis robotMedianTypical range

Runtime20min

20 min130 min

Bottom of range

Price$299

$150$850

Near median

Weight2.02lbs

1.3 lbs4.8 lbs

Below median

Position shows where the figure sits across the tracked category, not a quality judgment.

Official referencesProduct page

OWNERSHIP

Living with it.

Dependable glass-cleaning performer with no documented regressions; suction seal loss dominates owner reports.

Consistent suction motor performance across multi-year use. Most common failure is suction loss from surface film or residue, not mechanical regression. Firmware updates addressed early app connectivity issues.

Owner effort~40 minhands-on per month

Reliability trend Stableowner-reported arc

What goes wrong · 4 documented · 1 self-recover

Occasional

Suction loss mid-paneUnit detaches, safety rope arrests fall

Owner fixReseat suction cup, restart path

Occasional

Pad streaking on panesVisible streaks on large windows

Owner fixExchange pad between windows

Occasional

App disconnect via WiFiRemote control lost, unit continues path

Self-recoversReconnect app when in range

Rare

Edge-detection stallUnit pauses at frame edges

Owner fixManual restart via button or app

Upkeep routine

Each useEvery cycle

Remove microfiber pad, rinse with water, and hang to dry before storage. · Wipe suction ring with a clean damp cloth to remove glass cleaner residue that degrades the seal over time.

Monthly12×/yr

Inspect safety rope for fraying; replace if any strand damage is visible before next use.

Seasonal4×/yr

Clean suction motor intake port with a dry brush to remove dust accumulation that reduces grip force. · Check pad contact surface on the cleaning head for mineral buildup; rinse with diluted white vinegar if present.

Yearly1×/yr

Inspect power cable and connector for sheath cracking; manufacturer recommends replacement if outer jacket is compromised.

Cost over time · past the sticker

$299 to buy. Ongoing running cost for this model hasn’t been assessed yet.

Safety notes

CautionSafety rope required for vertical use: Anchor point must support 3 kg minimum load.

CautionCracked or chipped glass prohibited: Damaged surfaces disrupt suction seal and cause falls.

NoteContinuous water drainage risk: Water drains down glass onto sill; manage drip to floors and frames.

RECORD

How the assessment has moved.

Every announcement, release and reassessment behind the current classification.

Coming soon

Just launched

Active updates

Settled

Discontinued

Sep 2026 · AssessmentRecord status: Verified → Provisional
Aug 2026 · AssessmentRobovations Score revised 62 → 70
Aug 2026 · AssessmentRobovations Score revised 63 → 62
Aug 2026 · AssessmentRobovations Score rescored under v4.2: 61 → 63
Aug 2026 · AssessmentRobovations Score rescored under v4.0: 73 → 61
Aug 2026 · AssessmentAutonomy Ladder reclassified III → II
Jul 2026 · AssessmentRobovations Score revised 65 → 73
Jul 2026 · AssessmentRobovations Score recorded at 65 of 100
Sep 2023 · UpdateHOBOT 388 app firmware addresses 5 GHz Wi-Fi dropout in owner reports
Sep 2021 · ReleaseHOBOT-388 window cleaning robot released in the US with ultrasonic spray

Editorial comparisons

Common questions

What people actually ask.

5 answered

OperationDoes the HOBOT 388 work on exterior windows?

Yes, worked from inside. HOBOT’s instruction is to tie the included 4.5 m safety rope, which it rates to 200 kg tension, to a fixture indoors before the unit goes on the glass. HOBOT specifies no exterior anchor point and publishes no height limit for the model.

OperationHow long does it take to clean one standard window?

HOBOT publishes a cleaning speed of 4 minutes per square meter, so a standard pane is a matter of minutes rather than a session. Owner reports note that heavily soiled glass may require a second pass with a fresh pad.

OwnershipHow often do the microfiber pads need replacement?

The included pads are washable and reusable. Owner reports suggest useful life of 30–50 wash cycles before cleaning performance visibly degrades. Replacement pads are available from HOBOT and third-party suppliers.

CompatibilityDoes the 388 require a Wi-Fi connection to operate?

No. Basic operation via the onboard button works without a network connection, and a handheld remote is included in the box. The companion app adds path-mode selection and remote start but is not required.

OperationWhat surfaces can the HOBOT 388 clean?

Manufacturer documentation specifies smooth flat glass only. Textured, frosted, or significantly curved glass is not supported, as suction integrity depends on a flat continuous seal. HOBOT states frameless-window support on other models in its range but does not state it for this one.

Availability

Where it's sold

We may earn commission from qualifying purchases. This does not influence classification.

We are no longer finding a current new-stock listing for this robot. Remaining offers may be used, refurbished, or third-party — confirm the condition and price on the retailer’s page before buying.

Amazon See current listings

Cite / Embed

Reference the HOBOT 388 Ultrasonic classification.

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Citation

Robovations. "HOBOT 388 Ultrasonic: Autonomy Level II (Assisted Autonomy)." Autonomy Ladder™, assessed August 2026. https://robovations.com/robots/hobot-388-ultrasonic/

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Where to next

Three ways to keep going.

For evaluators

Compare with a peer.

See the HOBOT 388 Ultrasonic and HUTT DDC55 side by side: autonomy level, Robovations Score, readiness, and price. Classification, not a verdict.

See the full comparison

Or compare with HOBOT 2S, Ecovacs Winbot 920, Hobot 298.

For browsers

See every Level II.

Every robot we’ve classified at assisted autonomy. Sorted by readiness, score, and price. Filter by category, manufacturer, or release date.

Browse the database

Updated weekly with new entries and reclassifications.

HOBOT 388 Ultrasonic

Will the HOBOT 388 Ultrasonic work on your windows?

The full spec sheet.

Living with it.

How the assessment has moved.

How HOBOT 388 Ultrasonic compares.

What happens when a robot window cleaner loses suction or power?

Robotic window cleaners: which design fits which window?

Window robots: which handle more than maintenance dust?

What people actually ask.