Half Marathon Pace Calculator

• •Use the Half Marathon Pace Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
• •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
• •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
• •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.

A half marathon covers 13.1 miles (21.0975 kilometers) and has become one of the most popular racing distances, attracting over two million finishers annually in the United States alone. Whether you are aiming for a personal record, targeting a specific time bracket, or running your first half marathon, knowing your required pace per mile is essential for race-day execution. This calculator converts your target finish time into the per-mile and per-kilometer pace you need to maintain, along with your average speed and an estimate of total calorie expenditure. Even pacing is the most energy-efficient race strategy for the vast majority of runners, and having a clear pace target for each mile helps prevent the common mistake of starting too fast and fading in the later miles. GPS watches and course mile markers allow you to check your split times against the calculated pace throughout the race.

• !Starting the race 20-30 seconds per mile faster than goal pace due to adrenaline and crowds, leading to premature fatigue and significant pace decline after mile 8-10.
• !Not accounting for course elevation -- hilly courses require 3-8 percent longer than flat courses for the same effort level.
• !Forgetting to add time for crowded start corrals -- chip time starts when you cross the mat, but it may take 1-5 minutes to reach the start line.