Lactate Threshold Calculator

Estimate practical LT1 and LT2 anchors from available data and use them for session design.

Threshold Anchors

Threshold Output

Calculate to see LT1/LT2 anchors and next training actions.

Lactate Threshold Calculator Guide

Estimate practical LT1/LT2 anchors from power and/or heart-rate inputs and convert them into session decisions.

LT1 and LT2 in practice

LT1 is a lower threshold often used to guide durable aerobic work. LT2 is the higher sustainable boundary used for threshold-focused work.

Field estimation is useful for planning, but ranges should be validated against repeat sessions and pacing quality.

Primary Sources for This Section

Adaptive estimation logic

If power anchors are available, this tool defaults to power-led threshold estimates.

If power is unavailable, it provides heart-rate-led threshold ranges and flags confidence limitations.

Field-estimation approach

LT2 (power) ≈ FTP or CP anchor

LT1 (power) ≈ 78% of threshold anchor

LT1/ LT2 (HR) derived from LTHR or Max HR pathway

These are planning anchors, not lab diagnostics. Use trend stability and repeatability to refine ranges.

If FTP is 280 W, LT2 anchor is near 280 W and LT1 anchor is near 218 W for aerobic durability sessions.

Primary Sources for This Section

Interpretation

  • Threshold anchors are planning tools, not lab diagnoses.
  • When both pathways are available, compare trend stability instead of forcing exact agreement.
  • Re-evaluate thresholds after meaningful fitness changes.

What to Do Next

  • Use Zone 2 ranges to complete low-intensity planning below LT1.
  • Use CP/FTP updates to keep threshold anchors current.
  • Track repeated session quality before making large zone shifts.

Methodology

Version v1.0
Updated 2026-04-22
Owner Cycling Regimen Editorial

  • Adaptive pathway

    Power-first when available, HR-first when power is unavailable.

  • LT1/LT2 context

    Outputs frame practical session anchors for endurance and threshold work.

  • Cross-tool alignment

    Designed to align with Zone 2 and CP calculators.

    Read source
About Our Calculation Approach

Frequently Asked Questions

Is LT2 the same thing as FTP?

They are related training anchors but not always identical. This tool treats threshold values as practical planning ranges.

What if heart-rate and power pathways disagree?

Use repeated sessions and trend stability to identify which anchor is currently more reliable for your setup.

Can I use this without lab testing?

Yes. This calculator is designed for practical field estimation and decision support.

Disclaimer: This calculator provides estimates based on published exercise science models. Results are not medical advice. Individual physiology, health status, and environmental conditions affect real-world outcomes. Consult a qualified healthcare provider or certified coach before making training decisions based on these outputs.