Welcome to the lactate threshold calculator. If you are a runner, an athlete, or someone who trains at the gym for fitness purposes, you may have heard about lactate threshold (LT)—and that’s why you’re here. LT is an exercise intensity factor that determines whether you can maintain your pace or if it will cause fatigue.
We have prepared this lactate threshold calculator to help you determine your lactate threshold heart rate (LT HR) using the required data and a proven formula.
In simple terms, lactate threshold, also known as the anaerobic threshold, is the exercise intensity at which lactate starts to accumulate in your blood faster than your body can clear it, leading to fatigue during physical activity.
Here is how lactate threshold works:
Simply put, lactate is constantly produced by muscles. At moderate intensity, lactate is recycled and reused as fuel, which helps maintain pace. At higher intensities, lactate accumulates faster than it can be cleared, causing fatigue.
For athletes in endurance sports, lactate threshold often matters more than VO₂ max. For example, if two athletes have roughly the same VO₂ max or max HR, the one with a higher lactate threshold will outperform athletes with a lower lactate threshold.
Lactate threshold directly affects:
We have built a lactate threshold calculator that you will find to be a useful and handy tool. It uses the Karvonen method, which relies on heart rate reserve (max HR - resting HR) to estimate your lactate threshold heart rate (LT HR).
Here are guide to use the calculator:
age from 220:Max HR = 220 - Your Age (e.g., 24 years old)Max HR = 220 - 24 = 196e.g., resting heart rate 70 bpm.85% lactate threshold factor for most adults, but if you have an accurate lab test or have determined through any method, fill it there.177 bpm. This field can also be used to determine your LT factor. Lactate threshold can be calculated using your max heart rate, resting heart rate, and LT factor. We use a commonly accepted method, first calculate the heart rate reserve (HRR), and then we apply LT factor to determine the lactate threshold heart rate.
Follow those practical steps for calculation:
First, calculate your heart rate reserve by subtracting resting HR from max HR:
Heart Rate Reserve = Max HR − Resting HR
Next, you can apply the lactate threshold factor to determine the lactate threshold heart rate:
LT HR = Resting HR + (HR Reserve × LT factor)
In the calculator, we use 85% as the default LT factor, which works well for most fitness individuals, but can vary from 80 to 90% for trained athelets.
Let's assume you max heart rate is 180 bpm, resting heart rate is 60 bpm, and LT factor is 85%.
Max heart rate: 180 bpm60 bpm85 percentLet's perform calculation:
Step 1: Calcuating heart rate reseve (HRR):
Heart Rate Reserve = Max HR − Resting HRHeart Rate Reserve = 180 − 60 = 120Step 2: Now apply the LT factor:
LT HR = Resting HR + (HR Reserve × LT factor)LT HR = 60 + (120 × 0.85)85% into decimal 0.85)LT HR ≈ 162 bpmThis example shows that your lactate threshold heart rate is 162 bpm before fatigue creaping in.
The following table shows typical lactate threshold heart rate ranges:
| Training Level | Typical LT Intensity (% HRR) |
|---|---|
| Beginner / untrained | ~50–70% HRR |
| Well‑Trained Endurance Athlete | ~75–90% HRR |
| Elite Endurance Athlete | ~85–95% HRR |
| General “Shortcut” Reference | ~85% HRR (often cited) |
Keep in mind that the ranges above are guidelines, not strict rules.
No doubt, we do our best to ensure the calculator’s high accuracy by using research-based, science-backed logic and formulas. However, a lab test cannot be replaced. Our calculator provides reliable estimates, though not as precise as a lab test.
Lactate threshold varies based on fitness level. Most athletes fall between 80 to 90% of heart rate reserve, which is considered a good range. Beginners or untrained individuals may be around 50 to 70% of HRR, while elite endurance athletes can reach 85 to 95%.