AcuRite (00613MB) Digital Indoor Humidity and Temperature Gauge

Best thermometer I’ve tried, have had 3 of these and now purchased another 10 for our office and inventory areas. Helpful to show high and low along with current (humidity and temp) so can track trends. Highly recommend!

Great little inexpensive sensor. Has somehow been running for 17 months on just one double A battery. It seems accurate enough. When I turn my humidifier on, number goes up, when I turn it off, number goes down (though it's the only sensor I have so I can't really compare). No complaints. It's one of those gadgets that does what it says it does and wins on price.

We bought two of these to measure humidity and temperature on two levels of our house, as well as a co-branded unit that provides indoor and outdoor readings. They're not all that expensive, easy to use, and provide a snapshot of the conditions in our house. However, perhaps the brand name should be "AcuApproximate," because we noticed that when we set all three of them up and placed them side-by-side-by-side, they showed slightly different inddor temperature and humidity readings. This isn't a show stopper, as we only use them to get a general sense as to the readings - but the imperfect accuracy of the AcuRites was a bit amusing.

Just doing the salt water test with a number of hygrometers. I already had 2 of these AcuRites so I wanted to test them against the TempPros I have...and just bought 2 more. I was surprised how accurate these AcuRites are with the saltwater test. In a ziplock bag, the saltwater should register 75% humidity. One AcuRite measures 75% and the other 73%. Not bad. The TempPros not nearly as accurate. One TempPro was 69% and the other two at 71% and 70%. The temps were consistent on all of them...around 70 degrees. I'd say for the money, get the AcuRites.

Excellent little thermometer and humidity monitor. Retains the last high and low temperature and humidity in the past 24 hours as well as current.

The first question ask by users of AcuRite humidity monitor is how accurate is the reading of relative humididty (RH) especially when the spec for RH is +-4% due to unit to unit variation. (Obviously, the company would like to ship all units they made to make more money. Tighter spec causes high rejects and the company will make less money or the cost for the AcuRite will have to go up.) Also the accuracy could degrade over time due to contamination of the humidity detector. There is no way for users to find out if they have bought an accurate monitor or one that is 4% or more off unless they do a two point calibration at room temperature using two saturated (with some undissolved salt left at the bottom) salt solutions each sealed in a ziplock bag together with the monitor. This is very easy to do for anyone. Just put the AcuRite in the sealed bag overnight then check the RH reading the next morning and you are done. Fortunately, the needed salts are also easy to come by as one is table salt (sodium chloride; the monitor should read 75% RH at 70 deg F) and the other could be driveway ice melt (calcium chloride; the monitor should read 31.5% RH at 70 deg F). Since bacteria could not grow in such salty solution, the sealed saturated solutions could be saved and reused over and over again allowing re-calibration whenever the user desires. I used two ziplock bag, each of which has two plastic cups. In one of these bags, each cup has 1/8 inch of water on top of 1/8 inch of undissolved table salt. Likewise, in the other bag each cup has saturated driveway ice melt solution. The procedures I used to do a comprehensive calibration are given below. Using these two saturated solutions, my measurements on the AcuRite I bought showed that for temperature from 39 deg F to 79 deg F and for relative humidity from 29% to 75% , the max error is 3% off in humidity occurred at very low temperature (39 deg F) (i.e 37%RH is actually 40%) and near room temperature, the error is only 1%RH. (Lucky me!) Actually, the AcuRite is both a digital humidity monitor (hygrometer) and a digital thermometer. The AcuRite I tested is surprising accurate over a practical range of temperatures and a practical range of relative humidity values (see details given below). The temperature reading is also quite accurate. It is very desirable to have a high accuracy humidity monitor and thermometer for use at home. In the summer, a high humidity house is uncomfortable. Worse yet, a humid basement smells foul allowing mold to grow and humid closets cause clothes to smell bad - a nightmare for many housewives. Knowing accurately the humidity allows one to take measure to lower it. With seemingly high accuracy, the AcuRite is surprisingly cheap. The comfortable relative humidly(RH) range to human body is recommended to be a region around 45%. American Society of Heating, Refrigerating and Air-conditioning Engineers Inc. (ASHRAE) recommends: ---RH ---------temperature ---- season 30- 60%----- 68-75degF -------winter 30- 60%----- 73-79degF ------summer "Elevated relative humidity can promote the growth of mold, bacteria, and dust mites, which can aggravate allergies and asthma" and "Relative humidity levels above 70% may lead to the development of condensation on surfaces and within the interior of equipment and building structures. Left alone, these areas may develop mould and fungi." Typically, room temperature is set at 70degF. Also I preferred a RH of 50%. At 45%RH, I feel dry and my skin starts to wrinkle. Sodium Chloride saturated solution is commonly used to calibrate a hygrometer (humidity monitor) at room temperature (70 deg F) which should give 75%RH. Thus the hygrometer needs to be calibrated again with another source with lower RH, such as Calcium Chloride (31.5% RH at 70 deg F) or Magnesium Chloride (33%RH at 70 deg F). If the hygrometer agrees with one of these values then one can assume it is accurate around 50% RH. If the hygrometer is used only at room temperature, it only needs to be calibrated by two saturated solutions (for example sodium chloride and calcium chloride). However, I have calibrated from 39 to 79 deg F. Table salt (sodium chloride) and driveway ice melt (calcium chloride) provide an inexpensive and convenient way to calibrate (or check accuracy) of a hygrometer over a range of temperatures and humidity values. I have calibrated my AcuRite unit by using sodium chloride and calcium chloride saturated solutions, each of which was placed in a ziplock bag together with the AcuRite. An accurate hygrometer is expensive and bulky and I was surprised at the seemingly high humidity accuracy of the Acurite which I purchased from Amazon. The attractive features of the AcuRite are: seemingly very accurate humidity and temperature readings across a useful range of humidities and temperatures(see calibrations given below), records the max and min humidity and temperature occurred within 24 hr interval and low cost. Also the display font for humidity is large enough for convenient viewing. These features are not expected from a $10 device. Calibration using saturated table salt (sodium chloride) solution Calibration is based on published measurements of equilibrium relative humidity(RH) vs temperatures above saturated salt solution by scientist(s). I will use these published RH values as standard. For table salt saturated solution, the published RHs, given below, surprisingly are almost a constant from 32 to 104 degF(the measurement increment was 5 degC). Temp (deg F) RH(%) 32-59 76 68-104 75 I found that there was no different from using table salt with and without iodine. So I used the former. I also found that salt slurry did not work well. I sealed the AcuRite and two plastic cups in a ziplock bag which was further sealed by Scott tape. Each cup has at least 1/8 inch of undissolved salt (at the highest temperature of measurement) with at least 1/8 inch of water above it. Each deg F change can cause 3% change in RH. Since the AcuRite with battery is a big thermal mass, I made sure that for each measurement, the temperature and RH were stable for at least 1/2 hr, a condition which turned out to be most difficult to meet. Measurement results are given below. I found that for temperature, the AcuRite seems to be about 1 deg F higher than another temperature meter which has fractional deg F. However, I will use the temperature displayed by the AcuRite. Low temperature measurements were taken in a refrigerator. It took about one week to do all the measurements. Temp (deg F) RH(%, measured) RH(%, from standard) Error(%) 41 74 76 -2 72 75 75 0 75 77 75 +2 77 76 75 +1 88 77 75 +2 90 76 75 +1 From the above table, at room temperature of 72 deg, the error is zero and from 41 to 90 deg F, the max error is 2%RH. I would say this is quite acceptable for home use. Next, I checked if the humidity is linear over a range of RH values and a range of temperatures by using another saturated salt solution. Calibration using saturated calcium chloride (CaCl2) solution at low humidity A better and purer source for calibration at low humidly is magnesium chloride. Over its saturated solution, the RH is 33% over practical temperature range. Pure Magnesium Chloride is available from amazon or ebay sellers. Another good source to use is Potassium Carbonate which another reviewer in this forum had used and which is also available from amazon or ebay. The equilibrium RH is 43% from 0 to 30 degC. However, I didn't want to spend the money and trouble to get them. I found that I have some Prestone Driveway Heat ice melter (available from Home Depot and Lowes) which turned out to be Calcium Chloride. But the purity of the source was unknown and this would cast doubt on the results. From the internet, I found that the published equilibrium relative humidity(RH) vs temperatures above saturated calsium chloride solution are: Temp (deg F) 41 50 59 68 77 RH(%) 40.0. 38.0. 35.0. 32.0 29.5 RH vs temp seems to be linear and the slope is bout -0.3%RH per deg F My measurement results are: Temp (deg F) RH(%, measured) RH(%, from standard) Error(%) 39 37 ~40 -3 79 28 ~29 -1 Thus at each temperature, there are now two data points. If the calcium chloride measurements were believable due to the unknown purity of the calcium chloride source, then the linearity of the humidity of Acurite over a temperature range from 39 to 79 deg F and over a humidity range from 29% to 75% is quite good for home use as the max error is less than 3%RH occurred at 39 deg F, which is too low for normal use. Near Room temperature , however, the error is about 1%RH, which is remarkably small. I believe that the humidity detector is polymer on a capacitor. Capacitor is a linear device and should response linearly to humidity absorbed. Thus for each temperature if two measured data points agreed with published data by other scientists, then it is sufficient to determine the accuracy and linearity at that temperature. I have verified the data agreement from 39 to 79 deg F. (Note that the calcium chloride purity is questionable. But the measured data did agree with published values.) Thus, within this temperature range, the AcuRite unit I bought seems to be accurate and linear. Ideally, one would like to further calibrate the unit with magnesium nitrate saturated solution which has a RH of 50-55% across practical temperatures. This would give three data points on a straight line to verify the linearity. However, I do not know how to get it easily and cheaply. In Summary: for temperature from 39 deg F to 79 deg F and relative humidity from 29% to 75% , the max error is 3% off in humidity occurred at very low temperature (39 deg F) (i.e 37%RH is actually 40%) and near room temperature, the error is only 1%. Max humidity After I wrapped the AcuRite in a wet paper tower, the humidity was 99%, the expected value. Update rate and modify the back cover to increase airflow through the unit For normal use, no modification is need as modification does not change the accuracy of humidity and temperature. Allowing more airflow than necessary may shorten the life of the unit by quicken the contamination of the humidity detector inside the unit. Modification only changes the response time when the humidity changes. For home use, the humidity and temperature are not expected to change so fast that the unit could not keep up. The unit updates the humidity and temperature about every 15 sec. After initial testings which showed that the unit was accurate, I invested time to modify the cover of the unit as the airflow through the unit is through a grill and could be increased to have a faster response time. Steps for the modification are given below: 1) The cover is held by 4 small screws. Remove them by a jewelry screw driver. 2) Separate the back cover from the main body gently and not too far apart as there is a ground wire of the battery housing connecting the two. 3) Remove the ground wire from the battery housing. Now the two parts can be separated. 4) There is a plastic stick used for changing deg C to deg F. It will fall out but is easy to put back during re-assembly. I drilled four 3/16 inch holes on each side of the back cover as well as one 3/16 inch at the center of the back cover. The above measurements were done on just one AcuRite which I bought. Because measured data points seem to agree with published values by other scientists, I am satisfied that the humidity and temperature of my unit are accurate and use it with confidence. However, beware that there are a large number of reviews in this forum who said their AcuRite is no good.

My coworkers and I had been arguing back and forth for months with maintenance about the workplace temperature. We were sitting around covered in blankets and heating pads, but HVAC claimed the temperature in the area was suitable. I bought this wonderful little monitor online and it has completely changed my workplace experience. We were able to argue that 66 degrees is not a suitable workplace temperature, and now I work comfortably in a cool 70-77 degree range, with a 16% - 29% humidity level. Some days when I feel the old chill I just look at my AcuRite and say "Stop being a big baby, it's 73 degrees". I love my AcuRite reader and it has never let me down. It's eliminated any question about what temperature my cubicle is and puts my mind at ease while trapped in a box all day. Easily the best product I've ever purchased for my cubicle. Durability - this little buddy has been with me for over a year and has consistently read temperatures accurately each and every day. There was one day I had a slight coffee mishap and my AcuRite was drenched. The screen went blank and I thought it was done for. I almost threw it right in the trash, but thank goodness I didn't because old reliable pulled through and was back to reading my workspace temperature two days later! It's now safely stuck at eye level by its magnetic strip on one of my cabinets. Improve your social life - The AcuRite has been a great tool in helping me build workplace relationships. It's unbelievable how focused on silly things people in cubes can become, and temperature is certainly a main focal point for almost everyone. You too can become the person that your coworkers come to when they want to know what the temperature is in the office. Build trust by letting others borrow it to see if their cubicle is warmer or cooler than your own. Disclaimer -- if you already suspect that you're the office oddball, this product may have the opposite effect on your workplace social life. I can imagine this would be a great product for a house too, but I already have three thermostats that help me monitor temperatures constantly at home. But if you work in an office, think of how much more interesting your day would become if you could always know the office temperature. I love you AcuRite temperature monitor!

I absolutely love this temperature and humidity thermometer! I wanted one for work that i could put on my desk because the temperature changes so much in my cube and I am constantly calling the utilities staff at work here to correct the temperature almost every day!? At first, i didn't think the bigger non-movable humidity number display was a good idea but bought it anyway. I currently have two older monitors in my cube, one old school mercury monitor (think it's slightly off 2 degrees though? Hence why i bought this) and another touristy magnet monitor from Memphis (can hardly read it's so small, another reason i bought this new one on Amazon). Once i received this monitor and put in a AA battery (not included) it was up and running instantly, nothing to it, nothing to set up. So far i REALLY LOVE THIS temp and humidity monitor. It's the perfect size it really is. Again, before I received this in the mail i didn't like the thought that the humidity number was so much larger than the temp number and that it's not adjustable or movable and is stationary. I took my chances and glad that I did! I bought it anyway because it's such a small desktop monitor and fits nicely by your computer screen, on shelf, magnetic shelf, file cabinet, anywhere really! Overall I'm very pleased and now I'll be able to argue the wrong temp with the utility staff here at work next time it's muggy or uncomfortable in my cube. As for accuracy, i have two other thermometers and like i said, the old mercury one must be off because my Memphis Touristy magnet and my new AcuRite Thermometer are both spot on! Only other way to measure the accuracy was to purchase two like some have done here which i think is overboard. I think it's pretty accurate compared to my Memphis Magnet which is also a mercury magnet. Actually the more i look at it in person....it's kinda nice the humidity number is larger giving you the comfort level with the "OK" symbol up front and you can read the temp perfectly anyway with no problem. Another Bonus I love is it gives you the highs and lows and now i have PROOF how miserable it gets at my desk sometimes ...and can either show the utility staff or my boss now at work (before i bought this temp monitor people thought I was the problem, not the temp, haha). Now it's in their face!

Súper fácil funcionamiento, muy exacto y muy util!!! Tengo ya tiempo con el y funciona de maravilla, estoy por comprar otro para otra habitación que requiero monitorear niveles de humedad.

Having bought cheaper types to monitor the condensation issues in a 400 old house l found major differences in accuracy which defeated the purpose. This model was recommended on a website l was looking at so l bought it and quickly realised how good it was.Well worth the extra few quid.

AcuRite humidity monitor is very accurate. The best ever. Reasonably priced.

他の種類と色々比較してみたけどこれが一番正確だと感じました リセットせずに平均が更新されるのも助かっています

Muito Bom. Comprei desconfiado da temperatura do ar condicionado. Mede a umidade também.