Half Marathon to Full Calculator

Marathon Time Prediction Formula:

\[ T_{mar} = T_{half} \times \left(\frac{D_{mar}}{D_{half}}\right)^k \]

Predicted Marathon Time:

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1. What is the Marathon Time Prediction Formula?

The marathon time prediction formula estimates your full marathon time based on your half marathon performance, accounting for the non-linear relationship between distance and fatigue. The formula uses an exponent (k factor) to model how performance declines over longer distances.

2. How Does the Calculator Work?

The calculator uses the following equation:

\[ T_{mar} = T_{half} \times \left(\frac{D_{mar}}{D_{half}}\right)^k \]

Where:

\( T_{mar} \) — Predicted marathon time (minutes)
\( T_{half} \) — Your half marathon time (minutes)
\( D_{mar} \) — Marathon distance (26.2 miles)
\( D_{half} \) — Half marathon distance (13.1 miles)
\( k \) — Fatigue factor (typically 1.06)

Explanation: The k factor accounts for the fact that running twice the distance takes more than twice the time due to accumulated fatigue.

3. Importance of Accurate Prediction

Details: An accurate marathon time prediction helps with race pacing strategy, training plan development, and setting realistic goals to avoid hitting the wall.

4. Using the Calculator

Tips: Enter your recent half marathon time in minutes and adjust the k factor if you know your personal value (1.06 is typical). Beginners might use a slightly higher k (1.07-1.08) while elite runners might use lower (1.04-1.05).

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this prediction?
A: For well-trained runners, it's typically within ±5% of actual marathon time when using recent half marathon results.

Q2: Should I adjust the k factor?
A: More experienced runners can use lower k values (1.04-1.05), while beginners or those prone to late-race fatigue might use higher (1.07-1.08).

Q3: Does this account for course difficulty?
A: No, you should adjust for elevation and weather conditions separately. This assumes similar course profiles.

Q4: Can I use other race distances?
A: For best accuracy, use a recent half marathon time. Predictions from shorter distances are less reliable.

Q5: How should I use this for pacing?
A: Consider running the first half 2-3% slower than half your predicted time to account for late-race fatigue.