I was working out last night, and I hardly ever bother with the heart rate thingies. But I decided to see where I was, so I put my hands on the sensors, and it showed my HR.

For fat burn, the chart on the machine said I should be above something like 130. For cardio, my heart rate should be above 168 or something. I had been doing the elliptical for about 15 min. Well my heart rate was at like 175, lol. I wasn't working THAT hard...I was breathing and sweating a bit, but it wasn't intense cardio or anything. As far as I know, my heart is normal...I just had a physical a few weeks ago, lol.

So is that accurate? Was my heart really working that hard? Or is the heart rate sensor like the calories burn, just a "rough estimate?"

The hand sensors are notoriously wrong.

I agree. And if you have someone wearing a HR monitor on the next machine, your machine will display their HR.

The heart rate sensors are often wrong, yes. On the other hand, I often have a heart rate of 175ish when I am wearing my Polar on the elliptical machine. After 15 mins you could have been at that rate. I often get in the low 180s before I notice much conversational impact.

I wear a HRM for accuracy and mine is unfortunately one that "chatters" to the machines next to me. Luckily most people at my gym don't wear a monitor and it doesn't bother them lol.

For me anaerobic threshold is about 178+, I can jog all day at a pace of about 8mph and barely break 160. My resting heart rate is reasonably low though (about 50-52).

The sensors on the equipment seem to be somewhere in the ballpark but I highly recommend getting a HRM and learning how your own body works.

I have a Polar HRM that I haven't used for a long time, but on Friday I used it again as I've now got a fitness program made my a personal trainer, so I need to track my heartrate. There is some delay on the cardiomachine screens I've noticed, but they're generally only a few beats different from my HRM.
I'm a bit confused too what HR I should train at but the personal trainer I saw recommended aiming for about 140, so I'll stick with that for the next 6 weeks and see what happens.

Yeah my treadmill at home regularly says I have a hr of 200 when I am barely walking. And then it is 92 when I am sprinting.

Exact same for me. I use it out of curiosity now. If I tried to keep my heart rate at like 140 for the "weight loss" effects I'd have to be going super slow.