How many calories you burn during cardio depends on a few things. Mostly, how hard you are working along with how accustomed to the movement your body is will determine how many calories you will burn. For example walking on a treadmill at 3.5 mph without an incline will burn fewer calories than walking uphill outside at 3.5 mph. They’re both walking at 3.5 mph, but of different demands and intensities. This question often comes up in the form of “what is the best cardio”? The best form cardio is really the one that you will do on a consistent basis!
In short, you and your intensity will determine how many calories your cardio session burns. Intensity can be measured in many fashions but use a “talk test” to start. If you can speak with full sentences, you are at a low intensity. If you can only comfortably produce short sentences, you are at a moderate intensity. Finally, if you can only produce one word answers, you are working at a high intensity. If you are new to cardio, work at low intensities and progress to moderate intensity as the weeks go by. Higher intensities will not only burn more calories during cardio, but after cardio as well. Be sure to work up to it in baby steps though. Doing too much too soon can lead to injury or burn out. As always, consult your healthcare provider before increasing your activity.