SC42 Professional Digital Hygrometer Indoor Room Thermometer | Humidity Gauge Pro Accuracy Calibration

I picked up the SMARTRO SC42 Professional Digital Hygrometer about two months ago to monitor my master bedroom because of bathroom with shower. This thing is impressive right out of the box. The 3.5" LCD screen is large and clear, with big digits that are easy to read even from across the room. The touch-activated backlight is a nice touch — it lights up for about 10 seconds when you tap the top, perfect for checking at night without turning on a lamp. Accuracy seems spot-on. It uses industrial-grade sensors (Swiss-made, according to the specs) and updates every 10 seconds. I compared it side-by-side with a couple of other thermometers/hygrometers I own, and it consistently matched or beat them. Temperature is within ±0.5°F and humidity within ±2% RH, which is excellent for this price range. I love that it shows 24-hour and all-time high/low records too — super helpful for tracking how my AC or humidifier is doing. It also has a comfort indicator that tells you if the room is too dry, too humid, or just right. Setup was basically plug-and-play (2x AAA batteries, not included). It comes with a stand, magnetic back, and hanging hole, so you can place it anywhere. No real complaints so far — battery life is solid, and it feels well-built. If you want a reliable indoor consumer thermometer/hygrometer this one is a winner. Highly recommend.

Just got it today based on all of the reviews and I'm extremely Happy with my purchase! Super Easy to set up, literally I put the batteries in and it did whatever it had to do on its own! I Love that it comes with magnets attached and a little stand. I purchase the two-pack and stuck one to the fridge via the magnet and one in another area on its stand. Love the light button to make it bright when you need to see it, Love the Large Numbers, Temperature monitoring was spot on.... I can tell this will function perfectly and the batteries will last quite a while because the light goes to a dimmer mode until you need to make it brighter. We have Golden Retrievers with double coat fur and I'm always cold and can't tell if their rooms are too hot & humid... so these are perfect for each area they are in so I can keep them comfortable! Just got them today and already Love them! Great Price too! I would Highly Recommend and would purchase again! It was delivered FAST too.

So far so good, worked great right out of the box. Love that I can see humidity AND temp all in one place.

After having this for almost a full yr, here's an honest review: The problem with anything like this is knowing if they are truly accurate or not. It's now the end of July'24. I bought a large display clock that also shows date, day and temperature back in April. It's one that I can easily read from across the room--even in the middle of the night because it's backlit. Anyway, I've been checking the two against one another. would you believe they are almost always showing the same temperature even though not sitting next to one another, although in the same ~ 250 sq. ft. room. I guess that means either they're both right or they're both wrong. If wrong, what are the odds they'd both be wrong by the same amount/temperature. I lean towards they're both accurate!. Now here's what I don't like about it: 1) It's back lit --as long as you turn it on, and then it shuts off automatically. The problem with this one, although it has the backlighting, you have to touch the light icon on the top of the frame to turn it on. That means, for example, if you have it sitting on a shelf and you're in bed, you have to get up out of bed to go touch the light icon to turn the back lighting on so you can see the display. Therefore, it either has to be sitting on the nightstand right next to you, or you have to get out of bed to go touch it to see it in the middle of the night. It runs on two AAA batteries. If I were to have to change the batteries once a yr instead of every yr and half, that would be fine by me to be able to see/read it in the dark. I know some people are bothered by any light in a room, so maybe an option to either have the back lighting always on or always off. The other option would be to have a light sensor and when the ambient light in the room is dark, the light comes on and it goes off when the room gets light again-- kind of like the auto adjustment on my laptop. 2) Positioning of readouts: The humidity is displayed on top and the temperature is on the bottom. I can't reverse the positions though I'd like to. I care a lot more about the temperature inside than the humidity and the top figure is easier for me to see at a distance. Living in the PNW it's always humid to some degree-- inside, my home is normally good. If it should get too dry in here during the winter, I tend to know it by the uncomfortable dryness in my nasal passages &/or a sinus headache above my eyes. Anyway, I'd like to have the temperature displayed on top and the humidity on the bottom. or have the choice of which is displayed where. 3) Suddenly this evening, a gray shadow has shown up on the display when lit. It covers probably 7/8th of the display surface--only a little at the very top and at the very bottom aren't affected. However, even with the shadow, I can still read it the display. I don't know if it's simply because the batteries are old or if there's something else causing it. Hold on a sec and we'll find out. Nope! Not the batteries--something else. Those weren't even the original batteries I just replaced. Although fresh batteries made the display brighter, the shadow is still there covering most of the display. So it must be something in the digital display itself or the chip for it. Since I bought this in the summer of '23, the chip could quite possibly be one made during Covid. There have been problems with some chips made during that time when so much of the world's industries were shut down or running on skeleton crews. Maybe I just need to replace this entire unit instead of the batteries. Although this isn't one of the least expensive ones, it's MSRP was $21.95; with a sale price + a 15% coupon, I paid over $15.00 for it---about twice as much as the least expensive ones on Amazon right now. To be fair, they aren't back lit and this is. Still, I've had it for a few weeks under 1 yr and would expect to get more use than that out of any of them. I guess now, my bottom line is:: buyer beware! You may only get ~1 yr's use. If you want to consider this a throw away and replace it annually, it does appear to be accurate.

Easy to read, seems accurate and updates very quickly. Highly recomended… reasonable price, I bought two.

This thermometer is great! Very easy to use and accurate.

I set this in my humidor and it took a couple hours to reach the rh level of the humidor. I have a couple of other brands in there already so I know what the temp and humidity should be. I calibrated it once it reached the temp and humidity I knew was in there. 3 hours later cigars are 68 temp and 66 humidity. Holding the numbers solid. However, if I leave the door open too long and the rh numbers drop, it will take it a few hours to settle and read the proper rh again. I mean it creeps back up on the display. Nevertheless, it is working very well.

This is a solid little unit that provides helpful/accurate information. Easy to read numbers and graphs, and even has a light when neeeded! I had no idea how little indoor humidity I had in the winter time until I got this. Now I'm easily able to guage/achieve a more healthy indoor environment. A must have for cooler/cold climates. Would purchase again and am considering giving as a useful gift.

I use it for keeping my acoustic guitars at the right humidity levels (40~50%) which need an ajustable calibration offset controls (use humidity pack for control reference). Works fine and nice to have a readout backlighting when needed… (Cheaper hygrometers have no controls and can often be inaccurate up to 10%…)

I brought one checked it via a salt test bang on 75% brought another same as bang on 75%. Very pleased with the accuracy, very easy to use & has a decent magnet to hang up. to verify if your meter is correct put it in a plastic container with a cap filled with salt add a very small amount of water to the salt so you can still pick it up & it doesn’t run, seal it properly leave it a full 24hrs and it should read 75% if not it’s out & needs calibration )

He tenido muchos de estos y este es muy preciso, además se ilumina al moverlo, vale la pena el dinero q vale.

Working great so far and I’ve had for a few months now. Accurate measure and backlight is very bright but not blinding. Great display and easy to read.

Ottimo igrotermometro. Alla fine ne ho acquistati tre…. Dopo averne resi due di altro produttore che non ho trovato affidabili e che non permettevano la calibrazione se non in un piccolo range ristretto, inutile nel mio caso. Mentre questo permette una calibrazione senza vincoli !!! Ottimo prodotto.