Doesn't using my home Wifi reduce the amount of Data I need to buy from my cell phone provider?

Kindle syncs your reading with their cloud service, so you can read the same books on several devices and still know where you left off. For folks that have both smartphone and tablet.. and it is a very handy thing for those of us that do. But this only uses a tiny bit of data, no more than a few kilobytes.

Something on your phone is connecting while you are out... you need to find that something and turn it off. Or, go into your phone settings and find the option to "only update when connected to WiFi" or similar, depending on your actual device.

. If your WiFi drops, if you use your phone in the car, if your ISP goes down for a couple hours...and you use your phone in any of these situations...you're using data. It's also worth mentioning that what may feel like a small amount of data use can be a lot. Browsing the web for half an hour...not alot of data is used. It's mostly just text and images. you are doing more bandwidth heavy when using mobile data this month than you were the last (like watching videos or listening to music while not connected to wi-fi).

Using WiFi eliminates data usage when you are on the network, but as soon as you aren't using a WiFi connection, data is sent over the cellular data network. If your WiFi drops, if you use your phone in the car, if your ISP goes down for a couple hours...and you use your phone in any of these situations...you're using data. It's also worth mentioning that what may feel like a small amount of data use can be a lot. Browsing the web for half an hour...not alot of data is used. It's mostly just text and images. Watch a YouTube video for 3 minutes in HD...and that half an hour of web use is insignificantly small compared to what you've just used. So even if it doesn't feel like you've used alot of data, it's more than possible you've used more than you've accounted for. Also, I recommend you set your phone up to the WiFi networks of houses of Friends and family members, churches, fast food, your place of employment and anywhere else you may frequent. And leave WiFi on. This way, whenever you are at one of these locations, your phone will connect to a WiFi network. Some programs - mostly ones used for staying connected, such as social networking or email clients - will also automatically pull data every few minutes to keep up-to-date. It's best to disable the "Auto-Sync Data" option when you aren't on a network to avoid this. This way, it only refreshes the data if you open the program to refresh it yourself.

It's true if you are on wifi, your phone will not use mobile data but instead wifi data. The only way that your phones data usage could have increased is you weren't connected to mobile data more than wifi this month. Or you are doing more bandwidth heavy when using mobile data this month than you were the laste (like watching videos or listening to music while not connected to wifi).