Anaerobic Threshold Calculator

bpm
bpm
min/km
Health Updated 16 Jun 2026

The Anaerobic Threshold Calculator estimates the heart rate and running pace at which your body shifts from mainly aerobic to anaerobic energy production. It applies the Karvonen heart-rate reserve method at 85% intensity and approximates threshold pace from your current 10K pace. The formula used is: AT HR = resting HR + (max HR − resting HR) × 0.85; AT pace ≈ 10K pace × 1.05.

Formula

AT HR = Resting HR + HRR × 0.85; AT Pace ≈ 10K Pace × 1.05

Example Calculation

Inputs
  • Maximum Heart Rate: 185 bpm
  • Resting Heart Rate: 60 bpm
  • Current 10K Pace: 5.5 min/km

Suppose you enter: Maximum Heart Rate = 185, Resting Heart Rate = 60, Current 10K Pace = 5.5. The calculator applies the formula (AT HR = Resting HR + HRR × 0.85; AT Pace ≈ 10K Pace × 1.05) and shows all output values below. Change any input field to immediately see how the result changes.

Frequently asked questions

What is the anaerobic threshold?
It is the exercise intensity at which lactate begins to accumulate faster than your body can clear it. Training near this point improves your ability to sustain hard efforts.
When should I use this calculator?
Use it to set heart-rate and pace targets for tempo or threshold workouts, sitting just below the level where fatigue rises sharply.
What units should I enter?
Enter heart rates in beats per minute and your current 10K pace in minutes per kilometre.
How accurate are the results?
These are estimates from population formulas. A lab lactate test or a field threshold test gives a more individual value.
How do I interpret the result?
Aim to keep threshold sessions around the AT heart rate shown; stay below it for easy runs and push above it only for short intervals.
How can I verify the calculation manually?
Use the displayed formula and work through the numbers step by step. If your manual result differs slightly, check rounding and unit conversions first.
Can I use this for planning and budgeting?
Yes. Run best-case, expected, and worst-case inputs to compare outcomes and make safer planning decisions.