Online Calculator for 85% of Age-Predicted HRmax

Use the traditional formula to find your target heart rate for vigorous exercise.

Heart Rate Training Zones

Visualization of heart rate zones based on your age.

What is 85% of Age-Predicted HRmax?

The value representing 85% of your age-predicted maximum heart rate (HRmax) is a key metric used to define the upper end of the vigorous intensity training zone. To find this value, you first need an estimate of your HRmax, which is the highest number of times your heart can beat in one minute during maximal physical exertion. The most common and traditional equation to estimate this is simply 220 minus your age. Once you calculate 85% of age-predicted HRmax, you get a target heart rate that helps ensure your workouts are strenuous enough to significantly improve cardiovascular fitness and speed.

This specific percentage is often used by athletes and fitness enthusiasts to guide high-intensity interval training (HIIT) and other challenging workouts. Training near this threshold helps your body improve its lactate threshold, meaning you can sustain harder efforts for longer periods. While it’s a valuable guideline, it’s important to remember that this is an estimation; actual maximum heart rates can vary significantly among individuals.

The Age-Predicted HRmax Formula and Explanation

The calculation is a two-step process based on the widely used Fox and Haskell formula. It provides a simple, accessible way to estimate your training zones without requiring a clinical stress test.

1. Estimate Maximum Heart Rate (HRmax): This is done using the traditional equation.
   
   HRmax = 220 - Age
2. Calculate the Target Percentage: To find your target for vigorous activity, you multiply the HRmax by 85%.
   
   Target Heart Rate = HRmax * 0.85

Variables Table

Variables used in the HRmax calculation.

Variable	Meaning	Unit	Typical Range
Age	Your chronological age	Years	10 – 90
HRmax	Estimated Maximum Heart Rate	BPM (Beats Per Minute)	130 – 210
Target Heart Rate	The desired percentage of HRmax for training	BPM (Beats Per Minute)	110 – 180

Practical Examples

Understanding how to calculate 85% of age-predicted HRmax is clearer with examples. Let’s see how it works for two different individuals.

Example 1: A 25-Year-Old Person

• Inputs: Age = 25 years
• Calculation:
  • HRmax = 220 – 25 = 195 BPM
  • Target Rate = 195 * 0.85 = 165.75 BPM
• Result: The target heart rate for vigorous training is approximately 166 BPM.

Example 2: A 50-Year-Old Person

• Inputs: Age = 50 years
• Calculation:
  • HRmax = 220 – 50 = 170 BPM
  • Target Rate = 170 * 0.85 = 144.5 BPM
• Result: The target heart rate for vigorous training is approximately 145 BPM.

How to Use This Age-Predicted HRmax Calculator

Using this calculator is simple and straightforward. Follow these steps to determine your target training zones.

1. Enter Your Age: Type your current age in years into the input field. The calculator automatically assumes the unit is years.
2. Review the Results: As soon as you enter your age, the results will update in real-time. The main result shows your target heart rate at 85% intensity.
3. Analyze Intermediate Values: The calculator also provides your estimated maximum heart rate (100%) and values for moderate (70%) and light (50%) intensity zones to give you a complete picture.
4. Interpret the Chart: The bar chart visually represents these different training zones, making it easy to see the difference between light, moderate, and vigorous effort.

Key Factors That Affect Maximum Heart Rate

While age is the primary variable in the traditional formula, several other factors can influence an individual’s actual maximum heart rate. It’s important to be aware of these as they can explain why your perceived exertion may not always align perfectly with a formula-based prediction.

• Genetics: A significant portion of the variability in HRmax between individuals is due to genetic predisposition.
• Fitness Level: While counterintuitive, a higher level of cardiovascular fitness can sometimes lead to a slightly lower HRmax as the heart becomes more efficient. However, fitness level doesn’t drastically change the true maximum.
• Altitude: Exercising at high altitudes, where there is less oxygen, can cause your heart rate to be higher at submaximal efforts and may slightly lower your achievable HRmax.
• Medication: Certain medications, such as beta-blockers, are specifically designed to lower the heart rate and will directly impact your HRmax.
• Temperature: Exercising in high heat and humidity places extra stress on the body, which can elevate your heart rate even at the same intensity level.
• Hydration Status: Dehydration reduces blood volume, forcing the heart to beat faster to circulate blood, which can affect heart rate response during exercise.

Frequently Asked Questions (FAQ)

Q1: Why is the “220 – Age” formula used?

A: The “220 – Age” formula is used for its simplicity and has been a standard in fitness for decades. While more complex formulas exist, this one provides a quick and reasonably accurate estimate for the general population.

Q2: Is this calculation accurate for everyone?

A: No. It’s an estimation for an average person. Individual maximum heart rates can vary by 10-20 beats per minute or more from the predicted value. The most accurate way to determine your HRmax is through a medically supervised maximal stress test.

Q3: Why train at 85% of my HRmax?

A: Training at 85% of your HRmax falls into the “vigorous” or “hard” intensity zone. This level of effort is effective for improving performance, boosting your lactate threshold, and maximizing cardiorespiratory fitness.

Q4: What if I’m a beginner? Should I train at this intensity?

A: Beginners should start with lower intensity zones, such as 50-70% of HRmax, to build a solid aerobic base before attempting high-intensity workouts. It’s best to consult a doctor or fitness professional first.

Q5: Are there other formulas to calculate HRmax?

A: Yes, several other formulas exist, such as the Tanaka (208 – 0.7 * Age) and Gellish (207 – 0.7 * Age) equations, which are considered more accurate by some researchers, especially for older adults.

Q6: Does my resting heart rate affect this calculation?

A: No, this calculation is independent of your resting heart rate. However, other methods like the Karvonen formula use resting heart rate to calculate target zones based on heart rate reserve (HRR), which can be more personalized.

Q7: Can I use this for swimming or cycling?

A: Yes, the principle applies to any cardiovascular activity. However, HRmax can sometimes be slightly lower in non-weight-bearing activities like swimming compared to running.

Q8: How does it feel to exercise at 85% intensity?

A: At this intensity, your breathing will be deep and rapid. You should find it difficult to speak more than a few words at a time. It should feel challenging and sustainable for only short intervals.