I know water is 1:1, but I am tired and I can not find how many ml of co2 is 1 gr of co2.

The reason I ask this question is that I have to insert a flowmeter into a co2 cylinder and let it run for two days at a flow rate of 1 ml per minute, The cylinder is 2 kg of co2 and I don't know if will last that long. yes I M THAT STUPID. I am expecting a gr of co2 been a ton of ml but...