Best Robot Vacuum Under $400: What You Give Up and What You Keep

Short answer: Under $400, the clearest gap in our dataset is mop lift, not climb height. A third-party spec table lists 8 mm (0.3 in) mop lift for the Roborock Q10 S5+, against 10 to 18 mm (0.4 to 0.7 in) on four higher-end models; Roborock publishes no mop-lift figure. Dock clearance varies by model, so measure your dock spot against the manual.

Pick by your situation

Choose the situation closest to your home. Each verdict uses a figure from a manufacturer document or listing.

Pet hair on a budget

For long hair, choose the Roborock Q7 M5+ or Q10 S5+ over the ECOVACS Deebot T8 AIVI. Both Roborock models list a dual anti-tangle setup: a JawScrapers Comb main brush plus an anti-tangle side brush. The T8 AIVI's spec table makes no anti-tangle claim. Check price

The eufy 11S MAX lists BoostIQ 2nd Gen auto suction boost on thicker carpets, but our dataset has no brush figure for it. Check its spec sheet before choosing it for pet hair.

Small apartment or tight dock spot

Per the manual's dock diagram (direction not labelled), the Dreame D20 Pro Plus needs 1.5 m and 0.5 m of clearance, so measure your spot against the diagram. The Roborock Q10 S5+ dock measures 8.3 x 7.0 x 10.2 inches. Check price

Hard floors only

If every room is hard floor, mopping decides the choice. The Dreame D20 Pro Plus manual does not recommend mopping carpets, so keep the mop off rugs and replace the mop pad every 3 to 6 months. The eufy Omni C20 documents room-temperature drying for its mop, per eufy's own article. Check D20 Pro Plus price or check Omni C20 price.

You want self-empty

Records name four of these models as auto-empty: the Roborock Q7 M5+ and Q10 S5+ ("with Auto-Empty Dock"), the Dreame D20 Pro Plus ("Auto-Empty Robot Vacuum and Mop") and the ECOVACS Deebot N8 Pro+ ("Auto Empty"). Confirm the dock in the box you buy. The D20 Pro Plus manual lists its dust bag every 2 to 5 months.

First-year running cost

Count parts per year from the manuals, then add the live price of each exact part. The D20 Pro Plus manual gives its dust bag interval as every 2 to 5 months, and its mop pad as every 3 to 6 months. The ECOVACS Deebot T8 AIVI's disposable cleaning cloth is replaced after each use. Our dataset has no consumable intervals for the eufy 11S MAX, so leave its row blank.

What you give up, and what you keep

• Give up anti-tangle on the T8 AIVI. Its spec table makes no anti-tangle claim, while both Roborock models list dual anti-tangle brushes.
• Give up carpet mopping on the D20 Pro Plus. Its manual does not recommend mopping carpets.
• Give up mop lift on the Q10 S5+. A third-party spec page gives 8 mm (0.3 in) (Roborock publishes none), against 10 to 18 mm (0.4 to 0.7 in) on the T50 MAX PRO Omni, X10 Pro Omni, X9 PRO Omni and Qrevo S5V.
• Keep carpet boost. The Q7 M5+ has Carpet Boost, the Q10 S5+ auto-boosts on carpet, and the eufy 11S MAX and Omni C20 both list BoostIQ carpet boost.

Climb limits do not separate these tiers. The Q7 M5+ manufacturer page lists 20 mm (0.8 in); the Q10 S5+ spec page and the D20 Pro Plus retailer leaflet give the same 20 mm (0.8 in). The X9 PRO Omni, X10 Pro Omni and Qrevo S5V also list 20 mm, and only the T50 MAX PRO Omni lists more, at 22 mm (0.9 in).

Check the first-year cost, not only the sticker

1. Take the price from the live retailer checkout, not from this page.
2. For each consumable, count replacements per year from the intervals above, and record the exact compatible part's live price.
3. Add cleaning solution only where the manual permits that liquid.
4. Electricity: use your measured energy use and your own tariff. This guide has no tariff.
5. Leave any unverified cell blank. Do not total a year without measured inputs.

How we chose

We compared dated catalog entries below $400 by stated use case, published specifications, price and availability. We do not present retailer review totals as independent editorial ratings.

See our pet-hair guide, hardwood-floor guide or the full shortlist.

Sources and method

• Roborock Q10 S5+ product page, checked October 17, 2026
• robot-review.com spec page, Roborock Q10 S5+ (third-party), checked October 17, 2026
• Roborock Q7 M5+ product page, checked October 17, 2026
• Dreame D20 Pro Plus user manual, checked October 17, 2026
• eufy 11S product page, checked October 17, 2026
• ECOVACS DEEBOT OZMO T8 AIVI product page, checked October 17, 2026
• eufy Omni C20 room-temperature drying article, checked October 17, 2026

We compile manufacturer documents and cited independent tests; we do not test products ourselves.