How many calories burnt on elliptical 30 mins??

To get the most accurate number for you personally, the best thing to do is buy a heart rate monitor. Polar is a great one. I know my treadmill at home reads quite a bit higher in calories burned than my hr monitor does. So the machines are more of an average than an exact reading. MFP seems to be more of an average, too.

I think the 200 calories sounds more accurate, I have found the elliptical to be a little easier than running, for example.

The "very general rule" is 8-10 calories per minute of vigorous exercise.

My HRM tells me I burn about 10 calories per minute with the resistance set at 5 and my speed at 7 mph. I'm 139 lbs.

I found mfp to ridiculously overestimate on the elliptical. I'd go with your HRM if you have one? If not, the machine sounds a little low. I'd guess, as you look quite 'light' in your pic, that you'd be burning around 250 in a half hour, with a moderate level of effort. But obviously this is also a bit of a wild guestimate.

That's funny, I've found it almost amazingly close for my size, age, and intensity. But I also get on the elliptical, set the resistance very high, and work out so that my heart rate is teetering on the edge between "Cardio" and "Too High" (usually about 160, varies with age), and keep it there for the whole workout. The one we have at work is a high-end Precor with a heart rate monitor built in, and it's using my weight to help calculate calories and my age to track my heart rate, so I'm thinking it's in the ballpark at least.

I think the MFP elliptical setting is based on that type of a workout - high-level sweaty cardio. If you're going lighter, it's quite possible your machine is closer than MFP.

The elliptical I use reads between 15 and 16 calories per minute for the intensity of workout I do. We have several exercise support/training folk that my workplace contracts to support us, and the one I work with watched my workout one day and calculated out the calories, and the machine was correct to with 20-30 calories on my 700-calorie workout that day. So it's not perfect, but it's darned close.

If you have access to another elliptical machine, try to put the same effort into it and see what it comes up with. Or you can probably calculate the calories somewhat more accurately somewhere if you track your heartrate and enter your weight and height.

In any case, my workout would burn about 450-500 calories in 1/2 hour. I'm 6' 3" and 220+ lb. I bring my heart rate to 160. I set the resistance to "13" (if that means anything, I'm sure the numbers differ from model to model, but I'm using a Precor and I think the resistance stops at "20"). I do 4 miles in 45 minutes (so 5 MPH). And I generate 220-240 watts sustained. This is all according to the machine.

If you're a lot smaller, use a much lower resistance, go more slowly, etc etc, 200 may not be that far off. In any case, it's not going to be off by more than half, so you're looking at a discrepancy of 200 calories a day or a pound every 18 days. I'd just take the average and go with it.