The ThermoPro TP55 Digital Hygrometer Thermometer shows indoor temperature and humidity on a 4 inch screen with digits large enough to read across a room. It records 24 hour and all time highs and lows, displays a comfort icon for dry, comfortable, or humid air, and updates every 10 seconds.
It fits growers running plant rooms or a small greenhouse, keepers of birds and other animals, and homeowners tracking basements or workshops with indoor climate gauges. Readings display on the unit itself, so you check conditions in person rather than through an app.
Specifications
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Display: 4 inch LCD with large digits, humidity shown above temperature
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Controls: Touch sensitive buttons on the front face
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Backlight: Touch activated blue backlight that turns off automatically
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Temperature Accuracy: ±1°F
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Humidity Accuracy: ±2% RH
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Refresh Rate: Every 10 seconds
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Records: 24 hour and all time maximum and minimum readings
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Comfort Indicator: Icons for dry, comfortable, and humid conditions
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Units: Switchable between Fahrenheit and Celsius
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Placement: Fold out tabletop stand, wall mounting hole, and rear magnets
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Power: Batteries included
Reading Humidity and Temperature at a Glance in Plant Rooms, Basements, and Animal Spaces
If you are starting transplants indoors, overwintering tender plants, or keeping a basement dry enough to store seed and tools, the TP55 gives you a reading you can see from the doorway. The 24 hour low tells you how cold a plant room dropped overnight, which helps you decide whether a seedling heat mat or a thermostat change is needed.
The humidity readout sits on top in larger print, so you can spot damp conditions that call for better moisture control before mold sets in. The magnets hold it to a metal shelf or rack, and the stand lets you move it from room to room as you check different spaces. Front touch buttons mean you can switch units or turn on the backlight without taking it off the wall.
What to Expect from the ThermoPro TP55 Digital Hygrometer Thermometer in Real Use
Accuracy draws steady praise. Owners comparing it against other hygrometers, a weather station, a probe thermometer, and wall thermostats found close agreement, within a few tenths of a degree and a handful of humidity points. Readings have stayed accurate after two years of use. The TP55 is not an instant read gauge, though. A unit moved from a much hotter or cooler space can take 15 to 30 minutes to settle on the correct reading.
The large digits and auto off backlight are easy to read in dim rooms, and the magnets hold firmly on a fridge, bird cage, or metal storage rack in a basement or workshop. The 24 hour records proved useful for adjusting heat based on overnight lows.
For the most accurate results, keep direct sun off the back sensors and use the stand so air circulation reaches the rear of the case. A separate owner chose to replace the included unbranded batteries with a trusted brand as a precaution against battery corrosion.
Real-world performance notes sourced in part from verified Amazon customer purchases.
Frequently Asked Questions
How do you reset the 24 hour high and low on the ThermoPro TP55?
Press and hold the max and min button on the front of the unit for a few seconds. The 24 hour high and low clear and start recording again from that point. The all time high and low records are kept separately and run from the last battery change, so you can still see the extremes over a longer stretch after resetting the daily readings.
Why does a new digital hygrometer show the wrong temperature at first?
The sensors need time to match the air around them. If the thermometer has been sitting somewhere much hotter or colder than the room where you set it up, it can show an incorrect reading for 15 to 30 minutes while it acclimates. The same thing happens on a smaller scale when you carry it between rooms with different temperatures. Give it time to settle before you compare readings or make adjustments to heating or humidity.
Where should you place an indoor hygrometer for the most accurate reading?
Keep it out of direct sunlight, especially on the back of the case where the sensors sit, and away from heaters, vents, and appliances that put out heat. Standing the unit on its fold out stand leaves space for air to move around the back, which tends to give more representative readings than mounting it flat against a wall or a warm appliance. In a plant room or greenhouse, set it at the height of your plants rather than near the floor or ceiling.
