Best HRMs?

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I just want something that tells me how many calories I've burned during my day! I know some days I've burned more calories than others. Like today I walked twice as much as I i normally do but I have no way of accurately tracking how much I've burned. It's frustrating at the gym not knowing how much I've burned too! So what are good devices/good brands? I probably won't get it til Easter or my birthday maybe because they are pretty expensive and I'm a broke college student haha