For the other direction, based on a couple of centuries of data: https://www.state.gov/foreign-language-training/ https://www.state.gov/foreign-language-trainin

For the other direction, based on a couple of centuries of data: https://www.state.gov/foreign-language-training/ https://www.state.gov/foreign-language-training/ Some languages take english L1 speakers 3x as long to learn as others. I agree with GP's 2 years for Cat I-II languages (assuming you're mostly living there and learning the language in your spare time, not intensively).