I am definitely not the right person to answer this, but tagging so it shows up on my wall.

Tagging

For the OP, you can use the 220-age (+6 if female) formula. It isn't the best, but it does have the virtue of simplicity. Just be ready to adjust this up or down based on your experience.

The setting will have some impact on the calories reported as it will impact the ability of the FT4 to determine how hard you are working. The other inputs are age, sex, and weight. And, again, it will be an estimate based averages.

I like to use "highest seen"

Based on that, you could use 187.

One thing that you will find as you get in better condition is that it will be harder to get your heart rate up to Max. That is one reason folks run intervals. This gets the system primed, and, by the end of the series, you are hitting the Max during the fast part of the interval.

For me when I am most fit, I only hit HRmax during my kick to the finish at the end of a 5K.

If that 187 came near end of workout at that high HR, your muscles were already tired and couldn't push the heart as high.

That's why all HRmax tests are fast ramping, within about 12-15 min you'll be hitting max, because tired muscles just can't push it higher.

If you had decent warmup and got up to 187 near start, add 5.
If this was near end of your last described workout, add 10.

And if you want some HR zone ranges that at least incorporate a value you can indeed measure, resting HR, then try this.
www.calculatenow.biz/sport/heart.php?

The fat-burning zone is the current fad name for the much longer known Active Recovery HR zone, is is good for day after hard efforts - get the blood flowing, aid repair, but don't add more load that needs repair to muscles trying to already.
Tempo is not commented on, because except for race day, usually not a good training zone. Uses too much carbs and is intense enough to need a recovery day, but not intense enough to really cause improvements like higher zones can.

Also, for cheaper Polar like that with no VO2max stat, yes the HRmax is important for a chance at decent calorie burn.
It assumes that if your BMI (height & weight) is in the bad range (age & gender), then your fitness level is also bad, or VO2max.
Which is usually not a good assumption.
That stat with HRmax then determines calorie burn.

Also, to your interval level, the harder you push, the shorter it needs to be. Exactly like lifting. Lift the most weight with short rep ranges, then decent rest, and can do it again. If the rest is too short, you ain't doing that weight again.
So for really good HIIT routine, 15-45 sec for hard effort, 3 x as long for the walking rest. About 10 reps. Notice how high you can get the HR then.

And actually, if HRmax goes up as a stat compared to where it was before, and you did a certain % of that but it goes down, you'll get less calorie burn now. if HRmax is coming down, then indeed more calories burned.

If treadmill access, you can always test it out. Since not much cardio, may not matter much.
http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

Thank you so much for clearing that up! I hit the 187 during really hard active intervals during HIIT exercises. Some exercises, I go straight from 140-185 in about 40 seconds. So that counts right? I do 20 seconds on and 10 off (I follow the fitnessblender videos on youtube) and each exercise is 4 reps. I've tried 40 on and 15 off but I find that very difficult because I usually push it hard. I should just add 5 to 187 right? That's what it says on the website you posted too.

I don't really know what a fat burning zone is. I've read about keeping your heart rate in the fat burning zone while working out. Initially when I started running on the treadmill, I would make myself come down to 140-165 because I'd start running and constantly hover between 160-185. I didn't know better. Now I don't bother about it because the concept just sounds silly and 140-165 doesn't feel like I'm working out at all.

Initially, when I had the max HR set to 195 (according to what I read on different sites), the numbers for calories burnt were too high. I never felt like I had burnt that much. One hour of zumba would show up as 800 calories. Granted I always give it my best, but it still felt like too high even after I got fitter and more efficient and didn't feel so tired at the end of it. So I made it 208 just based off that.

So getting more efficient with movements will indeed cause you to burn less, especially if there is no way to increase intensity. Running you just go faster, weights you just add more to the bar. Zumba .... well, it's to the beat of the music, hard to swing more or faster unless the class is more advanced by faster beat music.

But, you becoming fitter doesn't cause you to burn less if you weigh the same - misunderstanding caused by the cheaper HRM's as I described above. So they'll easily go from overestimating to under because you became fit and HR lower for same level of effort, so it thinks you are burning less even though weight is the same and you are burning the same.

Fat-burning zone is where your energy source is about 50% fat and carbs each. Going up in intensity and HR zones you burn the same quantity of fat, but more carbs and calories overall, therefore the ratio of fat lowers. The myth fad that has been slowly going away because of the current HIIT fad that is misapplied, is that you should stay in that zone to burn the most fat. False, burn more calories and same amount of fat going harder.

Also be aware hard each and every workout doesn't mean better - unless you are merely going for calorie burn and not really improving the body by the exercise.
Exercise if done right tears the body down - it's the rest for recovery and repair that actually builds it back up. You do hard everyday because it feels right, you can easily be killing that repair process.

As to my comment on fad HIIT routines, I mean compared to what it used to mean before the name was tacked on to every routine someone could think of.

Imagine lifting. The positive response and getting stronger happens when you overload the muscle by going up to max what it can handle. If the muscle is tired and can't do what it could otherwise - is that overloading, will it get the same positive improvements? No. What if you keep the weight the same, never increasing it? No.
Do some squats with a weight that is near max for 8 reps. Now, which rest period is going to allow you to do that much weight for another 8 reps - 15 sec or 90 sec?

Those videos aren't HIIT, despite them using the name, not with rests shorter than the hard effort. Because very quickly your hard effort isn't as hard as it could be. If you are doing a 4 reps of some bodyweight exercise, then they are making up for ease of doing it by making the rests shorter. That's more tabata intervals, not HIIT. You aren't overloading the muscles for improvement, you are overloading the cardiovascular system for improvement. Still beneficial, but not the same thing.
That's fine, it's a way to make something seem tough, shorten the rests. But it's no longer the same overload with weight or effort.

Just saying, if this is start of exercise, you'll get benefits out of almost everything you do, even if it's not what could be obtained.

The 185 you are seeing sounds like the anaerobic spike, same thing you'd get from lifting heavy weight. But still a good indicator. Most will see HR increase as session goes on, but if too long can't reach the same max, which means the earlier hard efforts weren't really that hard. And running up around max is super intense, if you can really keep that up for 20 min, then you are likely about 80-85% of HRmax.
I would test your HRM though with treadmill - you might be surprised how much you burn, since it's not really possible to get a feeling for that.

You and another person could go in to Zumba class the same weight in body, arms, legs (since lifting them), and both be coordinated with body and do the moves same efficiency.
You'd burn the same calories. But you could go in being in great shape you are, they could go in and you could barely hear the music over their wheezing. Fitness just determines how easy or hard the effort will be for you.
Like breaking that 15 lb dumbbell free from gravity by picking it straight up from the floor. Male or female, old or young, weak or strong - same energy required to lift it. The other stuff just determines how easy it is for you. If weak that was a workout and body may try to improve, if strong then body thought nothing of it.

So the Zumba feeling that easy is no longer a workout for the heart/lung system, you got plenty there to spare. But it'll still work the muscles and joints and be beneficial. Like I walk 4 mph flat now and HR barely goes over 90, which is about the start of the aerobic exercise range. That ain't a workout for me that requires any improvement. If I only did that for months I'd lose fitness actually. But it's a great warmup and cooldown to something else to get the blood flowing and then stretch.

Traditional HIIT as it used to be known was to get as close to lifting for those that only wanted to do cardio, perhaps for a sport. Same overload on muscles used, if diet allowed same increase in strength and muscle.
So just as you can only lift to close to max when you have enough rest, and the hard effort is short in comparison, so also with traditional HIIT. 15-45 sec max effort, 3 x as long for easy effort, doing some cardio like running. Can't do that on treadmill correctly either. Only need about 8-10 reps.
And just like you wouldn't lift with same muscle day after day, HIIT needs repair and rest if done right.

But if you aren't doing a sport, and are doing lifting already, skip the HIIT and just get the real best results by the lifting. If you like the cardio do it in that Recovery (aka Fat-burning) zone the day after, or if you like the intense nature, do what you can in intervals after your lifting, (which won't be much since they should be tired).
But since you don't enjoy cardio, unless you just need to burn more to eat more to adhere to the diet, just do the lifting and take the deficit from total daily burn.
Or indeed do the Zumba as something fun you enjoy and burn extra there.

4-5 days a week isn't "only" - that's excellent. With couple rest days means you can have a couple really intense days to recover from.


You taking longer rests just means you could indeed get more intense. Or else you selected a routine for advanced and you aren't really there yet for strength/fitness. But keep it up. So that's good you've seen active demo of the effects of rest being too short.
Same thing happens on day to day basis as during the workout too. Imagine how bad your intervals would become if you did 30 seconds strong, and then 30 sec strong, and then 30 sec strong. That final one would not really be strong compared to first one. Same thing can easily apply day after day. Easy day allows hard day to be more intense.

So if you did about 30 min with HR up at 180, that was right at or barely below lactate threshold. I'd bet you were at 85% of HRmax.
That would put HRmax at 212.

If you are personally curious where it's at, even though you don't want to really do much cardio, and feel like doing a puke test, there is a way. But unless doing endurance cardio and training specific HR zones, not really needed.
http://www.myfitnesspal.com/blog/heybales/view/testing-hrmax-vo2max-with-max-treadmill-test-643927