The truth is that tuning is so simple and so many people want to overthink and overcomplicate it. A five digit flashing digital display does not guarantee accuracy or usefulness.
If you understand how a uke is designed built and set up, you will realise that a simple tuner is all you need as a player. The instrument is not complex.
The industry standard identifies 12 ratios of a root frequency to another frequency. They have the musical terminology "interval". They create a 12 note chromatic scale between octaves. The mathematical system has the musical terminology "Temperament". You can change the root frequency (the A note audio frequency) on most electronic tuners if you want to, usually you use A=440Hz and then the software in the tuner applies the 12 ratios or intervals to calculate the 12 other frequencies in each octave. Your uke is designed with frets and a set-up that splits the strings into these same ratios or intervals to produce the 12 notes in each chromatic octave.
As an example of the ratio: The Fifth Interval ratio in the industry standard called "Equal Temperament" = 1.49. This is not the 1.5 ratio that is need to get the Perfect Fifth ratio or interval. It is about 2 cents different. You use fretting technique to get rid of the 2 cent "error" so you can make a perfect fifth interval. You will never be able to get it in all keys at once by trying to tune your uke so the E/A of C/G ratio or interval is exactly 1.5. If your uke is designed and set-up to the standard the E/A and C/G ratio or interval will always be 1.49 when you tune the open strings.
Its all effectively hard wired by design. If you want to vary from the standard, you need to get a new set-up done, you can't change the fret spacing and the set-up technician has adjusted the nut and saddle to fine tune the intervals to the industry standard, so your fifth interval is adjusted to be 1.49 not 1.5. It is a waste of time trying to second guess your electronic tuner and use anything other than the industry standards. The whole system is set up so all you need to do is clip on the tuner and twiddle the four tuner knobs and then start playing.
Makers and tuning technicians need to fiddle more to do set-ups and test the instruments, so they can take advantage of a fancy tuner. But all a player needs to do is to tune the opens strings and start playing. The simpler you keep it, the better it will work. Having a tuner that is fancy and has more flashing lights wont help you, it just makes it seem more complicated. Which is why most players do not need a fancy tuner, you just need one that is easy to read and does not have buttons or features which get in the way. One of my tuners has two knobs, one has three functions the other has 7, IE 21 variations. If I am doing a set-up type activity I might use a few of them. Tuning up to play, I use the simplest function. The Snark is a very simple tuner, you do not need much more if you are a player.
You will see internet videos and discussions where punters can't get their tuner to have the perfect fifth interval of 1.5 and they say the tuner is faulty. What is faulty is their knowledge of how the tuner is designed and programmed.
It will usually be programmed so the fifth interval is always 1.49, not 1.5. You can get tuners that are used for fretless instruments like violins that have different sets of the 12 ratios or intervals (called temperaments) programmed into them.
If you use a different set of ratios or intervals (collectively called a temperament) for your ukulele, it will often be great in one key, but when you want to change key you need to retune the uke because of the way the frequency ratios or intervals work mathematically. So, having a tuner with 10 temperaments sounds great, but in reality it is not really practical. You are stuck with Equal Temperament if you want to play in several keys without re-tuning. Again the best tuner for a player is one that is very simple and easy to use.
Hands-free mode (let the tuner auto-detect the strings you're trying to tune)
