Putin's Military Overcommitment to Ukraine

How much military does a normal country need at home ready to respond to domestic instability or invasion along these lines? I shouldn't really quite know how to go about doing this. But let's focus on the soldiers because they're the people that could be used in that way. So America has a ratio of one, one uniform soldier for 237 net. And then you go to what you might think of as like more classical European military powers such as Russia. It's not an all-out war by any means but very large percentage are clearly stretched.