Fitbit, which one?

The Fitbit is not for you. It does not have a heart rate function. It is a pedometer.

I think this is how it works since the more steps, the more calories you burn. For things like elliptical/bike riding you will have to manually enter the calories. I am waiting on mine to come in the mail. I chose the zip for the price and because I really don't encounter stairs on a regular basis in my everyday life, if I decided I wanted to climb stairs I would have to look for some to climb so not so much an issue.

One thing that appealed to me about the fitbit is that my activity level changes greatly from day to day. I work at a small rural hospital and there are some days I spend most of the day sitting and others where I spend the whole shift (12-16 hours) on the move so I hope this will help me keep more accurate account of my calorie burn since there will be a big difference between a slow day and a busy day. I like the idea that with the fitbit I will only have to enter my non-impact activities (I am not a runner).

Oh cause online it showed calories burned. So I assume its just estimating by steps?

"Your tracker and Dashboard show an estimated number of calories burned for that day based on your BMR (Basal Metabolic Rate), which we calculate using the height, weight, age, and gender information you provided us with when you set up your Fitbit account.

When you sync your tracker, Fitbit replaces your estimated calorie burn with your tracker's data. If you manually log activities, the calories burned by doing those will be taken into account as well.

When you haven't synced your device or logged any activities, Fitbit tries to guess how many calories you have burned if you got out of bed, got dressed, went to your day job, came home, and did nothing much more than walk to your car.

Once you start logging activities, Fitbit stops estimating and uses the data you've provided instead. The more you wear your tracker, the more accurate your calorie burn data will be."

I'm not sure how it does it, but it's not just steps that it takes into account.

For example:

May 9
Steps: 6106
Calorie Burn: 2277

May 10
Steps: 6153
Calorie Burn: 2249

Notice that I took fewer steps on May 9, but burned more calories than on May 10 when I took more steps.

I'm sure some one who is more knowledged on the subject can give you more info. That being said, I still use a HRM for dancing and stuff. I also feel it has given me a better idea of how much I burn approximately, every day (TDEE value). It has shown me how inactive, I truly am.