Fat Burning Zone Calculator (Best Heart Rate to Burn Fat)

If you’ve ever ran on a treadmill and kept checking your heart rate in the so-called “fat burning zone” only to not see any change when you stepped on the weight scale?

You may be doing a lot of working out and cardio, but progress has frustratingly plateaued. As a personal trainer of 20 years, I hear this concern from new clients all the time. They think they’re staying in the “fat burning zone” but it’s something isn’t working.

Maybe you’ve been doing your cardio all wrong by wasting your time staying in the wrong heart rate zone. Slogging through slow and steady workouts can leave you frustrated without the results to show for it. You’re not lazy, you could just be in the wrong fat burning heart rate zone.

Below you’ll find an easy-to-use fat burning zone calculator. You’ll uncover your true fat burning zone when working out to lose weight.

How to Calculate Your Fat Burning Zone

All you have to do to calculate the best heart rate zone for fat burning is to enter your age and resting heart rate into the calculator. It’ll automatically determine the heart rate range for you to maximize fat burning when working out.

Here’s how to find your resting heart rate (without equipment):

1. Sit or lie down and relax for at least 5 minutes.
2. Use your fingers (not your thumb) to find your pulse on your wrist or neck.
3. Count the beats for 60 seconds using a timer.

This number is your resting heart rate — how many times your heart beats per minute when you’re at rest. It’s a sign of your cardiovascular fitness level, improving the accuracy of the calculation.

It’s best done first thing in the morning before getting out of bed for the most accurate reading.

The Truth About the Fat Burning Zone

When you’re working out at lower intensities (60-70%), your body has enough oxygen to break down stored fat for energy. But at higher intensities, your body shifts to using more quick burning carbohydrates because they’re faster to access under stress.

A common concern is whether the typical 220 minus age formula is even accurate for determining your fat burning zone. This might be a one-size-fits-all calculation, and it’s meant to give a ballpark number.

The fat burning zone calculator above uses the Karvonen formula with resting heart rate for better accuracy. But at the end of the day, these are all just estimates and not an exact science.

You don’t have to be overly concerned about staying in the fat burning zone the entire time you’re working out. Sometimes you may dip or go slightly over, but that won’t ruin fat burning.

Just try to stay roughly within the range most of the time and that’ll be good enough. It doesn’t have to be perfect every minute of your workout.

I’ve heard some of my clients say that they feel worried that low intensity workouts are too easy to actually burn fat. But burning fat doesn’t have to feel like death and fat burning thrives in lower intensity conditions. The aerobic system works differently than the anaerobic system.

The Fat Burning Zone “Myth”?

But here’s the catch…

You’ll burn a higher percentage of fat in this heart rate zone, but the total calories burned are lower than at higher intensities.

So, you’ll burn more fat proportionally, but not necessarily more fat overall unless the workout is long or combined with a calorie deficit.

60-70% max heart rate is the ideal fat burning zone because your body prefers fat as its main fuel source here. This is why doing longer low-intensity steady state (LISS) cardio sessions are great for fat loss.

LISS cardio can be easier to stick with for most people because it feels doable and not draining. It’s far easier to do 30 to 45 minutes of LISS a handful of times per week than keep up with a grueling HIIT (high-intensity interval training) workouts all the time that leaves you dreading your next workout.

HIIT and intense cardio workouts can be tough on the joints, tendons, and nervous systems. This is especially true for beginners, people carrying extra weight, or those coming back from a break. This is far less stressful on the body, making it safer and more sustainable, especially if you’re doing it multiple times per week.

Fat Burning Zone: How Long Is Enough to Actually See Results?

Ideally, you’ll want to stay in the fat burning zone when working out for 30 to 60 minutes per session.

This is the sweet spot that gives your body enough time in the fat burning zone to switch from burning quick energy sources like carbs to tapping into stored fat, kickstarting real, noticeable weight loss results.

Fat will become your body’s primary fuel source after the first 15 to 20 minutes when glycogen stores have depleted. Glycogen is a stored carbohydrate in your muscles and liver that your body prioritizes for energy before starting to tap into stored fats.

For weight loss and fat loss, try for three to five workout sessions per week in your fat burning zone. This is enough time in the fat burning heart rate zone for you to start seeing real results and see the scale going down. You can also combine with strength training to increase your metabolism even more.

It’s best to lift weights first and then follow with your cardio workouts to maximize fat burning. The strength training in the beginning will deplete glycogen, making it easier to start burning stored fat after cardio.

Amplify Your Results in the Fat Burning Zone

Bodybuilders have long used fasted cardio in the mornings to cut down even more before a show. You’ll maximize fat burning while glycogen is low. You’ll preserve muscle mass while dropping fat. And you can avoid excess fatigue and stress on your nervous system when you work out fresh in the morning.

High-intensity workouts can be stressful to your central nervous system, especially when in a fasted state. But LISS cardio, like being in the fat burning zone, will maximize fat loss. Just make sure you’re well-hydrated and well-rested before working out.

For even a bigger boost, try taking C8 MCTs with your morning coffee when intermittent fasting and doing cardio workouts. C8 MCTs are highly ketogenic and are quickly converted into ketones by your body. This helps to kickstart fat burning by flipping the metabolic switch so your body starts burning fat stores for fuel.

How to Track Your Heart Rate

Ideally, you’ll use a heart rate monitor to continually track and measure your heart rate during workouts because it’s going to be very difficult if you have to keep checking your heart rate to see if you’re staying within the fat burning zone.

There’s a saying: If you don’t track it, you can’t measure it. And if you can’t measure it, you can’t manage it.

This is going to be even more true when you’re working out in the fat burning zone. You might think you’re staying within the range, but without tracking your heart rate, it’s all guesswork. Using a heart rate monitor will take the uncertainty out and help you train smarter, not just harder.

I personally prefer to use an Apple Watch to track my heart rate. It’s very convenient to use and the data is reliable. It also allows you to move freely when exercising. But you can also use a chest strap or a simple fitness tracker such as the Whoop, Fitbit or the Oura Ring.

Whatever you use, it’s essential to have a real-time heart rate so you get instant feedback. You’ll know when to dial it up or ease it off. This makes each session more effective without wasting your time.

I know with the chest straps though is that they can be uncomfortable to wear. There’s also the friction of having to put it on and take it off. And keeping it charged, which can be too much of a pain to use for a lot of people.

Many cardio machines have built-in heart rate trackers that you can use. All you have to do is put your hands on the designated spot, and it should give you a pretty accurate reading for your heart rate.

But you’ll have to keep your hands on them a lot, which can be difficult if you’re walking on the treadmill or using the elliptical and needs your hands for arm movement.

Summary

• Your Personalized Fat Burning Zone: Use the calculator with the Karvonen formula by putting in your age and resting heart rate to find your optimal fat burning heart rate zone. This formula is more accurate than the 220-age method.
• Optimal Heart Rate Range: Keeping your heart rate within 60-70% of it’s maximum allows your body to efficiently use stored fat as fuel, boosting weight loss.
• Benefits of Low-Intensity Cardio: Doing longer sessions with LISS cardio can be more sustainable and easier on the body, especially for beginners or those with joint issues.
• Understanding the Fat Burning Zone Myth: While the fat burning zone leads to a higher percentage of fat burned, higher-intensity workouts will burn more total calories. You can also use both methods with 2-3 shorter HIIT workouts and 3-6 longer LISS workouts in a week.