hum Smart Rechargeable (Sonic, 3 modes, app) review 2027

What problem does the hum Smart Rechargeable solve?

The hum Smart Rechargeable is the cheapest smart toothbrush in our test, and the problem it solves is coverage: a teenager who brushes quickly and evenly has no idea which zones they skip. The app shows missed zones for $45, and in our test the teens used that app more than the adults did. That is the whole case for it. The verdict is blunt about the trade: as a plain brush the Sonicare 4100 is better for the same money. The hum is for the brusher who will actually open the app, not for the one who wants the strongest clean at the lowest price.

How did it score in our test?

We scored the hum across five criteria, and the total came to 7.6.

• Cleaning performance: 26 out of 35. We measured plaque reduction with disclosing tablets across six testers, and along the gumline specifically. The hum removed 76% of plaque.
• Comfort & pressure control: 16 out of 20. We judged noise, vibration in the hand, pressure sensor behaviour and gentleness on gums. The hum has no pressure sensor, so it lost points here.
• Battery & build: 11 out of 15. We counted days per charge at two minutes twice a day, checked the charger type, water resistance and travel case. The hum ran 10 days and charges on a proprietary base.
• Replacement head cost: 12 out of 15. We priced heads at the recommended three-month change and checked third-party availability. hum heads cost about $5 each.
• Modes & app: 11 out of 15. We counted brushing modes, timers and pacers, and asked whether the app coaching changed our testers' coverage. The hum has three modes and an app with a coverage map.

Where does the hum Smart Rechargeable stand out?

The app is the standout. It shows missed zones, and it does so for $45, which no other brush in this test matches. The brush itself is light and slim, with three modes, and the heads run about $5 each — the lowest head cost in the group. Teens in our test used the app more than adults did, which is the behaviour the product is built around. If the coaching gets a teenager to brush the zones they normally skip, the hum has done its job.

How does the Sonic technology work?

Sonic brushes vibrate the bristles side to side at high frequency rather than spinning a round head. The motion drives fluid between the teeth and along the gumline, and the bristle tips do the scrubbing. The hum runs this sonic action through three modes, and the app pairs with the brush to record which zones were covered during a session. The coverage map is the feedback loop: brush, see what you missed, brush again. Nothing about the hum's motor changes the physics — the value is in the map.

What is the hum Smart Rechargeable made of?

The spec sheet is short. Technology: sonic. Modes: three. Pressure sensor: none. Battery in our test: 10 days. Head cost: $5 each. App: yes, with a coverage map. ADA Seal: yes. Plaque reduction in our test: 76%. The charger is a proprietary base, not a USB port or a travel case, and the 10-day battery is the shortest in this comparison. The ADA Seal is the one piece of third-party validation on the box.

How does it compare with the brushes we tested against it?

The Sonicare 4100 costs $50 and scores 8.3. It has a pressure sensor, one mode with two intensities, 14 days of battery, $7 heads and 82% plaque reduction — but no app. For the same money you get a better plain brush and no coaching.

The iO Series 5 costs $100 and scores 8.6, with the highest plaque score in our test at 88%, five modes, a light-ring pressure sensor, 14 days, $8 heads and the Oral-B app. It is more than twice the price of the hum.

The Sonicare DiamondClean 9000 costs $230 and scores 8.8, with 85% plaque reduction, four modes across three intensities, a pressure sensor, 14 days, $10 heads and an app with a coverage map. It is the closest app-for-app rival, at five times the price.

Where does the hum Smart Rechargeable fall short?

Cleaning and pressure control are where it lost. At 76% plaque removal it is the lowest score in this group, behind the 4100's 82% and well behind the 88% of the iO brushes. There is no pressure sensor, so nothing warns a heavy-handed brusher. The battery runs 10 days, and it charges on a proprietary base rather than USB. Those three cons are the reason it sits at 7.6 rather than higher.

Is the hum Smart Rechargeable good value?

At $45 it is the cheapest brush here, and the $5 heads keep the running cost low. The Sonicare 4100 is $50 with $7 heads; the iO Series 5 is $100 with $8 heads; the DiamondClean 9000 is $230 with $10 heads. You are paying for the app and the low head price, and accepting the weakest clean and the shortest battery to get them.

Who should buy the hum Smart Rechargeable?

Teens and app-motivated brushers. If the coverage map is what gets a young brusher to reach the back teeth, the hum is the cheapest way to buy that feedback. If the app will sit unused, the Sonicare 4100 is the better brush for the same money.