If you are setup to automatically connect to known Wi-Fi networks, and you often times are able to, it can actually result in large battery savings. Transferri

If you are setup to automatically connect to known Wi-Fi networks, and you often times are able to, it can actually result in large battery savings. Transferring data over Wi-Fi is more efficient than going over a cell network. With how many network services exist on phones now days, your phone can spend a lot of time doing network transmissions. Wi-Fi is more efficient for this, thus the savings. You can see this in good cell phone reviews, they'll have a battery life test for Wi-Fi web browsing and another one for 4G web browsing, the Wi-Fi test will demonstrate a much better battery life. Another way to think about it, is if you are in an office building that doesn't have cellular antennas places throughout it, then to connect to the cell network your signal has to get through the building material. If there is Wi-Fi available, odds are those antennas are close by and easily reached. (Of course really noisy Wi-Fi environments can change the math on all this, but I do not know by how much.)