Threshold tool

Lactate Threshold Calculator

Quick estimates for LTHR, FTP, and threshold pace using practical field tests.

THRESHOLDS

LTHR

Heart rate

FTP

Power

T-PACE

Pace

What is lactate threshold?

Lactate threshold is a practical marker for the effort you can sustain before fatigue rises quickly. This calculator estimates field-test proxies: LTHR for heart rate, FTP for power, and threshold pace for running. Use repeatable protocols and compare trends, not isolated tests.

Calculator

Choose a metric and enter the data from your test.

Inputs

Choose a metric (heart rate, power, or pace) and enter your test data.

Metric

Use the average heart rate from a steady 20-minute time trial (running/cycling).

20-minute average heart rate

Enter average bpm from a strong but sustainable 20-minute effort.

These are practical field estimates. Use repeatable conditions and track changes over time.

Results

Enter test data to see your threshold.

Choose a metric and enter valid numbers to calculate.

Explained

What these thresholds represent and how to use them.

LTHR (heart rate threshold)

A practical proxy for the heart rate you can sustain around threshold. Often used to set HR zones.

FTP (power threshold)

An estimate of the highest power you can sustain for about an hour. Useful for setting power zones.

Threshold pace

A hard, steady pace you can sustain for a threshold-style effort. Useful for tempo and threshold training guidance.

How to use the threshold calculator

Choose the threshold type

Pick heart rate, power, or pace depending on the field test you completed and the training target you want.

Enter repeatable test data

Use a consistent test protocol and similar conditions so future results are easier to compare.

Update zones gradually

Use the output to refresh LTHR, FTP, or threshold pace, then check it against real workout feel and recovery.

FAQ

Which protocol is best?

Use the one you can repeat reliably. Compare results only across the same protocol and similar conditions.

Can I use treadmill data?

Yes, but keep in mind treadmill calibration can vary. Use trends and repeatability.

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