If your AcuRite Iris® (5-in-1) display unit or My AcuRite® account is reporting inaccurate rainfall readings, the rain gauge on the AcuRite Iris® (5-in-1) sensor can be calibrated to improve accuracy by following the directions below.

NOTE: The AcuRite Iris® (5-in-1) sensor comes pre-calibrated. The steps below are not required for a new sensor. 

To calibrate the rain gauge on the AcuRite Iris® (5-in-1) sensor:

Items Needed:

AcuRite Iris® (5-in-1) sensor, display console, plastic cup, pin, screwdriver

1. First, make sure the AcuRite Iris® (5-in-1) sensor is perfectly level using the built-in bubble level.
2. Place the display console close by so you can monitor it during the calibration process.
3. Make a pinhole in the bottom of a plastic cup. Hold the cup over the rain gauge and fill it with exactly 1 cup (8 oz.) of water, allowing the water to drip into the rain gauge. You should hear the internal buckets tip and see the water drain through the rain gauge.
4. A few seconds after each bucket tip, the display console will display rainfall in approximately 0.01" or more increments.
5. The cup of water should take more than 20 minutes to empty; a quicker period will result in an inaccurate calibration. (We’re trying to simulate a normal steady rainfall.) When the cup is completely empty of water, the display console should register 1.06"
   NOTE: We recommend performing this procedure multiple times BEFORE making any adjustments to the calibration screws to ensure adjustment is needed.

If the rain gauge doesn't register close to 1.06" after the cup is empty of water, then you should make an equal adjustment to the two calibration screws on the bottom of the AcuRite Iris® (5-in-1) sensor. Be sure to adjust both screws the same amount. Turning screws clockwise will increase the rainfall amount. Turning screws counterclockwise will decrease it.

Adjustment:

1. To adjust the rainfall reading by 2% turn both screws evenly 1/8 of a turn.
2. To adjust the rainfall reading by 4% turn both screws evenly 1/4 of a turn.
3. To adjust the rainfall reading by 8% turn both screws evenly 1/2 of a turn. 

There should be nearly an equal number of water drops (typically about 25 water drops) between bucket tips. If not, then adjust the calibration screws on the bottom of the AcuRite Iris® (5-in-1) sensor until an equal number of water drops are tipping the buckets. Then, restart the calibration procedure.

If you don't hear the buckets tipping or see water dripping alternately out of each drain, there may be an issue with the rain gauge or its adjustment. Please use the link below to access and clean the tipping cups within the sensor and verify they are seated correctly.

AcuRite Iris® (5-in-1) No Rainfall

Here's a video detailing the AcuRite Iris® (5-in-1) Rain Gauge Calibration Procedure that you may find helpful:

If you have accidentally removed the calibration screws or adjusted them unevenly, the following procedure approximately resets the screws to the Factory Default.

1. Tighten the calibration screws fully
2. Unscrew them 5 1/4 full turns evenly
3. Clear today's rain totals
4. Rock the sensor back and forth until you hear 10 clicks- you may need to open up the sensor and tip the cups back and forth manually.
5. In a minute or so the rain total on the display should be .10 inches (every click/tip should register .01)

• *To increase rainfall-turn screws clockwise
• *To decrease rainfall- turn screws counter-clockwise