respiratory rate

The watch do not measure your respiration. It uses the HRV to count the breaths.

https://support.garmin.com/en-US/?faq=2yEgS0Pax53UDqUH7q4WC6

When I manually count my breaths I get about half of what is reported by the respiration widget.

I use the 945 since 2.5 year 

Ok, thanks. Why is it called the respiration in bmp? That suggets the true rt.

And is it really, as you wrote, the half of the real rt?

I think that when you are counting the respiration rate changes. You are breathing more slowly when you are aware of your breathing, but it is pretty hard to count your breaths without being aware of it :-)

I know this 'problem'.

are you using a heart rate strap or only the watch optical?   

I guess i've never really tried to count to compare, don't really see how respiration rate can be a helpful metric for my training.  

Usually i'm around 16 during day, 13 sleeping, ~35 on a run (during workout maybe 38avg and often 40-45 during warmup), 

I use a heart rate strip and did't use the rr until now: last few years i have rapid acidification in the legs and probably suffer from some form of chronic hyperventilation at night. The (Garmin) respiratory rate might be very helpful for analysis. In this i cant use it.

What values do you get? 

Night between 9 and 13

Normal day :  10 and 20

Workout in D1: 25 and 45