On-site TEFL courses usually last 4 weeks. On a standard 4 week course you can expect the days to be very intensive, with a lot of work to be done in the evenings and at weekends too, preparing classes and writing assignments. Some courses are offered over 2, 3 or 5 weeks instead. With 2 or 3 week courses you should check carefully to be sure that this will be accepted by employers in countries where you want to teach. CELTA and Trinity Cert TESOL courses always last 4 (or 5) weeks when taken full time. There are also weekend or 3-day courses, sometimes designed as introductory courses, to give you a taste of TEFL to see if it's for you before you take the plunge into a longer TEFL certification program. A further option is an MA in TESOL, a route commonly followed in the US. As with most Masters degrees, these take one year or longer and consequently tend to cover theory and methodology in greater detail. Most online courses are sold as a number of hours of study. So one provider may offer 40, 80 and 120 hour online courses, for example. The time you take to do this of course depends on how fast and how often you work! Online TEFL courses, by their nature, can be taken part-time, and some on-site TEFL certification programs can be studied part-time as well. So the question 'How long does it take to get a TEFL certificate' depends entirely on the type of course.