There are approximately 33.814 US fluid ounces in one liter. If you are using the UK imperial system, one liter equals about 35.195 imperial fluid ounces. The difference is because a US fluid ounce is slightly larger than an imperial fluid ounce. So, for most purposes, especially in the US, you can use: 1 liter = 33.814 US fluid ounces This conversion is widely used for liquid volume measurements.