I've been trying to monitor it with a few programs but they all seem to be either underestimating or overestimating. Coming from someone with a bandwidth cap, I was just curious how much I'm looking at having this run during day to day computer usage
asked 21 Apr '12, 19:16
I don't have time to measure this myself, but I can give you a very rough guess: Between 0kB/s and 1kB/s on average -- for just mouse and keyboard input. If Synergy is idle then it will use no bandwidth (other than the heartbeat/keep-alive messages).
Each message is just a few bytes, and you probably won't see more than a handful of them every second. However, it depends on what you're doing -- if you copy a lot of text for example, then it might go significantly higher for a brief moment while it copies the text to the client.
Also, regarding your question about bandwidth cap -- like OliverG suggests, a bandwidth cap will usually only be applied to your internet connection. Since it's unlikely you are using Synergy over the internet, this shouldn't affect you.