The UK has knife crime but not knife murder, despite what the fearmongering press would have you believe. The UK murder rate is a quarter that of the US, and is in line with similar countries.
4.8 murders per 100,000 in the US vs 1.2 per 100,000 in the UK.
The figures _do_ take size into account.
United States: 4.8
United Kingdom: 1.2
vacri's statement seems completely accurate.
Murders in the US are currently sitting at 14k, ~11k of which are from firearms. The US only has 5 times more people than the UK, which would turn your stat into a rough US-equivalent of 1.7k.