Cycling & Running Training Stress Score (TSS), Intensity Factor (IF) & Variability Index Calculator

Compute workout TSS, Intensity Factor (IF), Variability Index (VI), and mechanical kJ.

Training Stress Score (TSS)
113.63 TSS
Intensity Factor (IF = NP ÷ FTP) 0.87 IF
Variability Index (VI = NP ÷ AvgW) 1.08 VI
Mechanical Work / Energy Burned 1,177.2 kJ (~kcal)
Inputs
⚡ Scenarios:
min
Total workout or ride duration in minutes.
W
Normalized Power (NP) or graded pace equivalent in Watts.
W
Simple arithmetic average power in Watts.
W
Athlete’s current Functional Threshold Power (FTP) in Watts.
Results & Graph
Training Stress Score (TSS)
113.63 TSS
Intensity Factor (IF = NP ÷ FTP)
0.87 IF
Variability Index (VI = NP ÷ AvgW)
1.08 VI
Mechanical Work / Energy Burned
1,177.2 kJ (~kcal)

Training Stress Score (TSS)

Graph 1 • Training Stress Score (TSS) • Domain Architecture & Live Telemetry Maps Workout Duration Minutes, Normalized Power Watts, Average Power Watts through Training Stress Score (TSS) Formula.
Training Stress Score (TSS) • Clinical & Physiological Reference Scale Low / Baseline Target / Reference Elevated / Watch High / Action Training Stress Score (TSS): 113.63 TSS Intensity Factor (IF = NP 0.87 IF Variability Index (VI = NP 1.08 VI Mechanical Work / Energy B 1,177.2 kJ (~kcal)
Graph 2 • Training Stress Score (TSS) Across Workout Duration Minutes Sweep (40% → 160%) Evaluates IF = NormalizedPower / FTP; TSS = (Duration_hrs × NormalizedPower × IF across 7 operating points (current input highlighted).
0 TSS 100.00 TSS 200.0 TSS 45.45 36min 68.18 54min 90.91 72min 113.6 90min 136.4 108min 159.1 126min 181.8 144min
Graph 3 • Joint Sensitivity: Workout Duration Minutes × Normalized Power Watts Compares Training Stress Score (TSS) when Normalized Power Watts is shifted +25% (solid) vs. −25% (dashed).
0 TSS 127.0 TSS 254.0 TSS --- Normalized Power Watts @ 75% 124.3 -30% 151.0 -15% 177.6 +0% 204.3 +15% 230.9 +30%
Summary: Riding 90 min at 235 W Normalized Power (0.87 IF, 1.08 VI) accumulates 113.6 TSS and burns 1177 kJ.
Summary: Riding 90 min at 235 W Normalized Power (0.87 IF, 1.08 VI) accumulates 113.6 TSS and burns 1177 kJ.
⚡ Send result to: BMI →Calorie & TDEE →Pace, 1RM & HR Zones →
Interactive chart & math engine powered by CalculatorGraph

Formula & Mathematical Methodology: Training Stress Score (TSS) Formula

IF = NormalizedPower / FTP
TSS = (Durationhrs × NormalizedPower × IF / FTP) × 100 = Durationhrs × IF² × 100
IF = NormalizedPower / FTP; TSS = (Duration_hrs × NormalizedPower × IF / FTP) × 100 = Duration_hrs × IF² × 100
  • workoutDurationMinutes: Workout Duration Minutes (min)
  • normalizedPowerWatts: Normalized Power Watts (W)
  • averagePowerWatts: Average Power Watts (W)
  • athleteFtpWatts: Athlete Ftp Watts (W)

Rounding: Clinical scores round to statutory integer or decimal precision; physiological metrics round to 2 decimal places.

Worked Example: Clinical / Physiology Scenario: Training Stress Score (TSS)

Compute workout TSS, Intensity Factor (IF), Variability Index (VI), and mechanical kJ.

  1. Enter lab values, anthropometric measurements, or performance test metrics.
  2. Evaluate the reference equation: IF = NormalizedPower / FTP; TSS = (Duration_hrs × NormalizedPower × IF / FTP) × 100 = Duration_hrs × IF² × 100.
  3. Inspect the primary classification, supporting indices, and 3 SVG charts.
Result: Computes Training Stress Score (TSS) via IF = NormalizedPower / FTP; TSS = (Duration_hrs × NormalizedPower × IF / FTP) × 100 = Duration_hrs × IF² × 100.

Frequently Asked Questions

How does the Cycling & Running Training Stress Score (TSS), Intensity Factor (IF) & Variability Index Calculator compute its result?

It evaluates IF = NormalizedPower / FTP; TSS = (Duration_hrs × NormalizedPower × IF / FTP) × 100 = Duration_hrs × IF² × 100 directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a target lab value or pace?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Are my health and biometric inputs kept private?

Yes. All calculations run 100% locally on your device with zero external transmission.

Health & Fitness · Endurance & Exercise Physiology

Cycling & Running Training Stress Score (TSS), Intensity Factor (IF) & Variability Index Calculator: inputs, method, and how to read the result

Compute workout TSS, Intensity Factor (IF), Variability Index (VI), and mechanical kJ.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Workout Duration Minutes: Total workout or ride duration in minutes.
  • Normalized Power Watts: Normalized Power (NP) or graded pace equivalent in Watts.
  • Average Power Watts: Simple arithmetic average power in Watts.
  • Athlete Ftp Watts: Athlete’s current Functional Threshold Power (FTP) in Watts.

What the calculation includes

With the default values shown, Training Stress Score (TSS) is 113.63 TSS. The calculation follows Training Stress Score (TSS) Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Workout Duration Minutes from 90 min to 99 min changes Training Stress Score (TSS) from 113.63 TSS to 124.99 TSS. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses peer-reviewed clinical and sports physiology formulas.
  • For educational and informational reference only; clinical scores do not replace physician judgment or laboratory reference ranges.

Scope: Global Clinical & Sports Science Consensus Check the assumptions and limitations against your situation before relying on the estimate.

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