How Many Calories Did I Really Burn

I want to figure out how many calories I need each day, and then subtract 500 calories from that to lose a pound a week (3500 calories are in a pound, divided by 7 days a week = 500 fewer calories per day). I am keeping track of all this now on my iPhone with an awesome free app called Lose It.

One of the hardest parts is determining how many calories I burn on the stationary bike that I work out on in front of the morning news. My iPhone app tells me I only burn 93 calories in 30 minutes, but I think it should be more than that.
I googled for how many calories did I burn, and went to the top six hits. I got a pretty wide range of answers, 119 – 211 calories, which doesn’t help much. Most of the sites required my weight, and there was not much choice in exactly how hard I worked on the bike. I would have guessed “moderate exertion”, but I have no idea how many miles per hour I am going, my bike doesn’t tell me. One site, which I thought was the best, let me pick the level of exertion by how many watts I was doing (using?), and I work at about 90, my bike does tell me this. I had to chose 100 watts. This site also wants male or female, age, height, weight and lifestyle (sedentary, somewhat active, etc). It returns for you how many calories you need per day based on your lifestyle and then how many calories you burn from exercise. I got 183 calories for 30 minutes of bicycling, which I think is more accurate. It also tells me my BMI and recommended minimums of various vitamins, minerals and other nutrients.

Here’s the site: http://www.nutritiondata.com/tools/calories-burned