Zone 2 Calculator Guide: Heart Rate, Power, FTP, LTHR, and Aerobic Training Targets
Calculate Zone 2 heart-rate or power targets from FTP, lactate-threshold heart rate, or heart-rate reserve so your easy endurance training stays truly aerobic.
A Zone 2 calculator helps runners, cyclists, and triathletes find the aerobic intensity range that is easy enough to repeat and steady enough to build endurance. Searches like "zone 2 calculator", "zone 2 heart rate calculator", "zone 2 power calculator", and "aerobic zone calculator" usually come from athletes who know they should go easier but do not know the target.
Zone 2 is popular because it solves a real problem: too many endurance athletes make easy days too hard. The TrainingDojo Zone 2 calculator gives a practical target from FTP, lactate-threshold heart rate, or heart-rate reserve.
Open the free Zone 2 calculator and use the result as the starting point for the training decisions below.
The Problem: Easy Training Is Easy to Overcook
Zone 2 should support aerobic development without creating the fatigue of tempo or threshold work. But if the range is vague, athletes drift upward until every endurance session becomes medium-hard.
A Zone 2 calculator gives you guardrails. Power, heart rate, and threshold-based inputs are not identical, but each can help define the aerobic range that belongs in base training, long rides, long runs, and recovery-supportive volume.
What the Zone 2 calculator Gives You
- Zone 2 power targets from FTP.
- Zone 2 heart-rate targets from LTHR or heart-rate reserve.
- A simple aerobic range for base training and endurance days.
- A clear next step into weekly plan design.
How to Use the Calculator
- Pick the input you trust most: FTP, lactate-threshold heart rate, or resting plus max heart rate.
- Calculate the target range before the workout.
- Start near the lower or middle of the range on long sessions.
- Watch for heart-rate drift, heat, fatigue, and hydration changes.
Common Mistakes to Avoid
- Treating Zone 2 as the hardest pace you can call easy.
- Forcing heart rate to match power instantly during warmup.
- Using Zone 2 for every training problem and ignoring intensity work.
- Copying someone else's Zone 2 range from social media.
Turn the Number Into Training
Zone 2 is most powerful when it fits into a full training week. It supports harder work, builds aerobic durability, and creates volume that most athletes can recover from. It is not a replacement for threshold, VO2 max, speed, strength, or race specificity.
Use the calculator to set the target, then use TrainingDojo to place Zone 2 rides and runs where they actually belong in your week.