1875 Rapitest SunCalc Sunlight Calculator for Gardens – Measures Full Sun, Partial Sun, Partial Shade, and Full Shade. Designed and Engineered in The USA.

Given the price, you can't expect lab accuracy. It's a good value.A couple of comments:1 - You need to scrub the probes before using. There is a scrubby sponge in the box.2 - Succulents are having their day in the sun, but this unit will not work for gritty succulent soil. Not enough soil contact, probably, and certainly you can't make mud of it for pH.3 - Light is measured in LUX, which is really not a measurement of anything plants need. You can get the same measurement on your cell phone. But a light meter that measures PPFD is quite expensive. LUX can be a good proxy measurement for outdoor sunlight, but for plants under grow lights like houseplants and seedlings, it's pretty useless.

I always have the hardest time figuring out if different parts of my yard are good for certain plants sun-wise. This Sun Calc is great. I've tried it in multiple parts of my yard and it reads accurately. One thing I noticed other reviewers saying is it did not give an accurate read and I want to give my suggestions for troubleshooting. First, this needs 12 full hours of LIGHT to read accurately. So it has to be put out at sunrise and picked up 12 hours later. If you put it out later and the full 12 hours run into evening darkness then that will throw off the reading. If it is a very cloudy day, that will throw off the reading. So do it on a day that is average for your area and make sure the sun calc is there for a full 12 hours of daylight. If none of that works, then you may have a faulty product. If you get a good product then this is AMAZING.

Updating Review - I took this out to use it this year and it did not work. I opened it up to change the batteries and the ones that came with it leaked and eroded the thin terminal metal so this no longer works. I thought it would be okay to store indoors but I guess the batteries need to be removed when not in use. This was a complete waste of money.Updating review - The company responded to me with the sun ranges for each category. Posting here if you are interested.Full Sun – 6 + hoursPartial Sun – 4-6 hoursPartial Shade – 1.5 – 4 hoursFull Shade – Less than 1.5 hoursI placed this in an area that I expected to be partial sun and that is what the meter showed. It is easy to assemble, turn on, and use. It is also easy to tell when it is still measuring sunlight.It would be nice it the calculated level lit up as a solid light instead of a flashing light. With how quick it flashed I had to cover the two closest bulbs to make sure I was seeing the correct one light up.They also have poor product support. I reached out to see how they calculate the sunlight levels for each category. Depending on where you look, you can get different hour levels for the different categories of sun. Some also measure morning, mid-day, and evening sun differently. The company never responded to me.

The first meter I ordered from Amazon did not seem to function properly. The pH and moisture seemed OK, but fertilizer always seemed to read at the low-end of ideal and light always seemed to read 2000 fc no matter how bright or indirect the sunlight. I filled out a return online and had a replacement within 3 days and a free return label -- good service.The replacement unit seems to function OK. Over the range of pH 6-8 the meter seemed accurate. I tested pH on distilled water (it was 7), on baking soda (it was 8) on soil of known slight acidity (it was 6-6.5). However, when tested on very acid soil (verified to be pH 4 with a chemical test kit), the meter read between pH 1-2.The moisture meter seems to work fine. It read 0 on dry soil, 9 on soaking wet soil, and somewhere in between on moderately damp soil.The light meter was way too sensistive. I compared it to a professional meter and it was reading 1000 footcandles when there was only 200 fc. I "recalibrated" it by putting black tape over 95% of the sensor on top until the readings matched the professional meter -- it is now more or less correct.The fertility meter seems pretty accurate. I mixed up a batch of half strength Miracle-Gro fertilizer solution and poured it over some old spent soil and took a reading -- it read "Too little". Using regular strength MG it read "Ideal" and using double strength MG it read "Too much". I've used this weekly to monitor my fertilizer levels and tell me when to reapply my liquid fertilizer to different vegetables and this is the most useful (and difficult to find) function on a meter like this.Something to note, you MUST insert the probes a full 3.5 inches into the soil for an accurate reading. This makes it difficult to use the meter in very hard clay soils or in shallow house plant pots (like my Bonsai trees).- Rob Thompson

I purchased this as a used item from Amazon warehouse and it came to me in pieces and did not work. I am unable to move the review on its functionality.