Your target heart rate is the range of heartbeats per minute you should aim for during exercise to get the most benefit without overexerting yourself. For most people, that range falls between 50% and 85% of their maximum heart rate, depending on how intense they want their workout to be. It’s a simple, practical tool for gauging whether you’re pushing hard enough to improve your fitness or coasting too easy to make progress.
How to Calculate Your Target Heart Rate
The most widely used starting point is estimating your maximum heart rate by subtracting your age from 220. A 40-year-old, for example, has an estimated max of 180 beats per minute (bpm). From there, you multiply by the percentage that matches your workout intensity. Moderate exercise sits at 50% to 70% of your max, while vigorous exercise falls between 70% and 85%.
For that same 40-year-old, a moderate workout means keeping the heart rate between 90 and 126 bpm. A vigorous session means staying between 126 and 153 bpm. These numbers shift with every birthday, so it’s worth recalculating once a year or whenever you start a new training plan.
There’s also a more personalized method called the heart rate reserve formula. Instead of using only your max, you subtract your resting heart rate from your max first. That difference is your “reserve,” the range your heart has to work with above its baseline. You then multiply the reserve by your desired intensity percentage and add your resting heart rate back. If your resting heart rate is 65 bpm and your max is 180, your reserve is 115. For 60% intensity: 115 × 0.60 + 65 = 134 bpm. This approach accounts for your baseline fitness level, so two people the same age but with very different resting heart rates will get different targets.
Why the 220-Minus-Age Formula Isn’t Perfect
The standard formula gives a useful estimate, but it can miss the mark by several beats per minute depending on your sex and fitness level. A study of 180 recreational marathon runners found that the formula overestimated max heart rate in women by about 5 bpm and underestimated it in men by roughly 3 bpm. That’s a meaningful gap when you’re calculating zones based on percentages of that number.
An alternative equation (208 minus 0.7 times your age) was similarly off for women in the same study. The takeaway isn’t that formulas are useless, just that they’re approximations. If you’ve been exercising consistently and your predicted max feels too easy or impossibly hard, trust your body over the math. A graded exercise test supervised by a professional gives the most accurate max heart rate, but for everyday fitness, the formula is a reasonable starting point.
What Each Heart Rate Zone Does for You
Heart rate zones break the spectrum from rest to all-out effort into tiers, each with a distinct effect on your body.
- Zone 2 (60% to 70% of max): This is where your body relies most heavily on burning fat for fuel through aerobic metabolism. It feels like a brisk walk or easy jog, comfortable enough that you can hold a full conversation. Building a base of Zone 2 training improves endurance and cardiovascular efficiency over time.
- Zone 3 (70% to 80% of max): A moderate-to-hard effort, like a steady run. You can still talk, but in shorter sentences. This zone strengthens your heart’s ability to pump blood and improves overall aerobic capacity.
- Zone 4 (80% to 90% of max): Hard effort. Conversation becomes difficult. Your body shifts toward burning more carbohydrates because it needs energy faster than fat metabolism can supply. Interval training often targets this zone to push your lactate threshold higher.
- Zone 5 (90% to 100% of max): Near-maximum effort, sustainable for only short bursts. This is sprint territory, useful for competitive athletes building top-end speed and power.
The “Fat-Burning Zone” Reality
You’ve probably seen cardio machines advertising a “fat-burning zone” at lower intensities. There’s a grain of truth here: in Zones 1 and 2, a higher percentage of the calories you burn come from fat. Your body has time to break down fat stores through a slower chemical process. As intensity climbs into Zones 3 through 5, your body increasingly shifts to carbohydrates for quick energy, burning proportionally less fat per calorie.
But percentage isn’t the whole picture. Higher-intensity exercise burns more total calories in less time, and it can improve long-term fat loss more effectively than staying in a low zone. You’re always burning a mix of fuel sources at every intensity. The best zone for losing fat is whichever one you’ll actually sustain consistently, whether that’s a 30-minute walk or a 20-minute interval session.
How to Monitor Your Heart Rate
The simplest method requires no technology at all. Place two fingers on the inside of your wrist or the side of your neck, count the beats for 15 seconds, and multiply by four. This works well for a quick check mid-workout, though it’s hard to do while running or cycling.
For continuous tracking, wearable devices fall into two categories. Chest straps use electrical sensors to detect the actual electrical signal your heart produces with each beat, making them the most accurate option. Wrist-based monitors (smartwatches and fitness bands) use light-emitting diodes pressed against your skin to detect blood flow through your arteries. They’re far more convenient, but their accuracy depends on fit, skin tone, and how much your wrist is moving during exercise. For casual fitness tracking, a wrist device is usually sufficient. If you’re training by precise zones or doing high-intensity intervals where every beat matters, a chest strap is the better choice.
When Heart Rate Targets Don’t Apply
Beta-blockers, commonly prescribed for high blood pressure and certain heart conditions, slow the heart rate as part of how they work. If you take one, you may never reach your calculated target heart rate no matter how hard you exercise. That doesn’t mean you aren’t getting a good workout; the medication is simply capping your heart’s response.
In this situation, perceived exertion is a better guide than a number on your wrist. The Borg Rating of Perceived Exertion Scale asks you to rate how hard an effort feels on a scale from 6 to 20. Most workouts should feel “somewhat hard,” meaning they take real effort but you can keep going. A practical shortcut: if you can talk in short sentences but not sing, you’re in a solid moderate zone. If you can’t talk at all, you’re likely pushing too hard. This talk test works for anyone, but it’s especially useful when medications or medical conditions make heart rate an unreliable metric.
Weekly Exercise Targets by Intensity
Knowing your target heart rate is most useful when paired with how long and how often you should exercise. For moderate-intensity work (50% to 70% of max), the goal is 150 minutes per week, or about 30 minutes five days a week. For vigorous-intensity exercise (70% to 85% of max), 75 minutes per week achieves comparable benefits in half the time. You can also mix the two: a couple of easy days and a couple of harder sessions.
If you’re starting from scratch, there’s no need to hit those numbers immediately. Build up gradually, adding five or ten minutes per session over several weeks. The target heart rate range gives you a way to keep each session honest. If you’re consistently below 50% of your max, you’re likely not pushing enough to trigger cardiovascular adaptations. If you’re regularly above 85%, you may be overtraining and increasing your injury risk without proportional benefit.