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Half Marathon Pace Calculator

Fitness & Health

Calculate the exact pace required to finish your half marathon (21.1 km / 13.1 miles) in a goal time, project your finish time from a target pace, or analyse an actual race result. Get 6 personalised training paces, km and mile split tables, equivalent projections for 5K to marathon, calorie estimate, performance level, and half-marathon specific race-day tips.

Units:
hminsec
kg

Explore This Tool in Context

Half Marathon Pace Calculator is part of the Fitness & Health collection. If you want a broader view of similar workflows, open the Fitness & Health category page or browse all QuickTools categories.

Common next steps after this tool include BMI Calculator, Calorie Calculator and Body Fat Calculator.

How to Use the Half Marathon Pace Calculator

1

Choose Your Mode

Select Goal Time → Pace to find the exact per-km or per-mile pace you must maintain to hit a target finish time. Choose Goal Pace → Finish Time to project how long the half marathon will take at a given pace. Use Actual Time → Pace Analysis to analyse a race you've already run.

2

Select Your Race Distance

The default is Half Marathon (21.0975 km / 13.1094 mi). You can also select 5K, 10K, full Marathon, or enter a custom distance in kilometres or miles — useful for local road races with non-standard distances.

3

Choose Metric or Imperial

Switch between Metric (km / pace per km) or Imperial (miles / pace per mile). Both pace formats are always shown in the results regardless of which unit system you select.

4

Enter Your Values

Depending on your mode, enter a goal finish time (hours / minutes / seconds), a target pace (minutes and seconds per km or mile), or your actual race result time. Enter your body weight to get a calorie burn estimate for the race.

5

Click Calculate

Instantly see your required pace, projected finish time, running speed in km/h and mph, and a fully broken-down split table at every 5 km (or 1 km for short races). Six personalised training pace zones are calculated directly from your race pace.

6

Review Training Zones & Race Projections

Use the Training Paces card to plan every session type (easy, long, tempo, intervals, strides). Race Projections show equivalent predicted finish times for 5K, 10K, and the full marathon at your current fitness level.

What Is a Half Marathon Pace Calculator?

A half marathon pace calculator uses the simple relationship Pace = Finish Time ÷ Distance to answer the three most important half marathon planning questions: what pace must I run, how long will the race take, and what does my past result actually mean?

The half marathon — exactly 21.0975 km (13.1094 miles) — is one of the world's most popular race distances, attracting both beginners and competitive runners. Unlike the full marathon, the half marathon is achievable for most recreational runners in 8–12 weeks of focused training, yet still demands smart pacing: running even one minute per km too fast in the opening 5 km typically causes a dramatic slowdown in the final 5 km.

Beyond pace and finish time, the calculator generates a complete set of training pace zones based on your goal race pace. These zones — ranging from easy recovery runs through sprints — tell you exactly how fast (or slow) to run for every type of workout in your training week. The zones are derived from the pacing ratios popularised by running physiologist Jack Daniels: easy runs at ~130% of race pace, long runs at ~120%, tempo efforts at ~93%, and interval work at ~87%.

The kilometer split table shows where you should be on the course at every 5 km checkpoint, helping you make real-time decisions on race day rather than relying purely on feel. Equivalent race projections let you cross-check fitness: if you've run a recent 10K in a known time, this gives a data-driven estimate for your half marathon potential.

Half Marathon Training Pace Zones Explained

Zone% of Race PacePurposeTypical Session
Easy / Recovery~130%Aerobic base, active recovery, fat-burning efficiencyMost daily runs, 30–75 min, fully conversational
Long Run~120%Build endurance, practise sustained effort, mental resilienceWeekly long run, 14–19 km, slightly slower than easy
Half Marathon Pace100%Race specificity, teach body the target effortLast 5–8 km of long run, or a controlled 10–12 km tempo
Tempo / Threshold~93%Push lactate threshold, raise sustainable speed ceiling20–35 min continuous or 2 × 15 min with 5 min rest
Interval / VO2 Max~87%Expand aerobic capacity and improve running economy5 × 800 m to 4 × 1600 m track repeats with rest
Sprint / Strides~80%Neuromuscular sharpness, quick leg turnover, injury prevention4–6 × 15–20 sec at end of easy runs, 2–3× per week

Worked Examples

Example 1 — What Pace Do I Need to Run a Sub-2-Hour Half Marathon?

  1. 1Mode: Goal Time → Required Pace | Race: Half Marathon (21.0975 km)
  2. 2Goal Time: 1 h 59 m 59 s (just inside 2 hours)
  3. 3Required pace = 7199 s ÷ 21.0975 km = 341.2 s/km = 5:41 per km (9:08 per mile)
  4. 4Speed: 10.5 km/h (6.6 mph)
  5. 5Training paces: Easy 7:23/km · Long Run 6:49/km · Tempo 5:17/km · Intervals 4:57/km
  6. 65 km split: 28:23 | 10 km split: 56:47 | 15 km split: 1:25:10 | Finish: 1:59:59

Sub-2 hours is one of the most coveted half marathon milestones for recreational runners. At 5:41/km it's attainable for well-trained club runners with 6–12 months of consistent weekly mileage. The key is keeping the first 5 km comfortable — resist the race atmosphere and start at 5:45–5:50/km before settling into race pace.

Example 2 — If I Run at 5:30/km Pace, When Do I Finish a Half Marathon?

  1. 1Mode: Goal Pace → Finish Time | Race: Half Marathon
  2. 2Pace: 5 min 30 sec per km
  3. 3Finish Time = 21.0975 km × 330 s/km = 6962 s = 1:56:02
  4. 4Speed: 10.9 km/h (6.8 mph)
  5. 5Training zones: Easy 7:09/km · Tempo 5:07/km · Intervals 4:47/km
  6. 6Race projections: 5K in 27:30 · 10K in 55:00 · Marathon in 3:51:44

A 1:56:02 half marathon at 5:30/km is a strong recreational result, faster than approximately 60–65% of half marathon finishers. Under the Riegel formula, this fitness level suggests a marathon potential of around 3:51–4:00 with appropriate marathon-specific training over 16–20 weeks.

Example 3 — I Finished a Half Marathon in 2:15:00 — What Was My Pace?

  1. 1Mode: Actual Time → Pace Analysis | Race: Half Marathon
  2. 2Actual Time: 2 h 15 m 0 s = 8100 seconds
  3. 3Pace = 8100 ÷ 21.0975 = 383.9 s/km = 6:24 per km (10:18 per mile)
  4. 4Speed: 9.4 km/h (5.8 mph)
  5. 5Equivalent: 5K in 32:00 · 10K in 1:04:00 · Marathon in 4:30:00
  6. 6Calorie estimate (70 kg runner): ~1,575 kcal / ~6,594 kJ

A 2:15 half marathon (6:24/km) is a solid first or early-career result. To go sub-2:00, you need to cut ~25 seconds per km — achievable in 3–6 months of structured training adding one weekly tempo run (5:57/km) and pushing the long run to 18–19 km.

Common Half Marathon Goal Times & Required Paces

Reference chart for popular half marathon (21.0975 km) finish time targets:

Goal TimePace (min/km)Pace (min/mile)Speed (km/h)Level
1:00:002:50/km4:35/mi21.1World record territory
1:10:003:19/km5:21/mi18.1Elite / national class
1:20:003:47/km6:06/mi15.8Highly competitive club
1:30:004:16/km6:52/mi14.1Strong club runner
1:45:004:58/km8:00/mi12.1Solid recreational runner
2:00:005:41/km9:09/mi10.5Popular benchmark goal
2:15:006:24/km10:18/mi9.4Recreational finisher
2:30:007:06/km11:26/mi8.5Beginner / first half

Frequently Asked Questions

What is a good half marathon time for a beginner?

For a first half marathon, any finish time under 2:30–2:45 is an excellent beginner result. The average half marathon finish time across all runners worldwide is approximately 2:05–2:15. A time under 2:00 places you roughly in the top 35–40% of all finishers, while under 1:45 puts you in the top 15%. For your first race, aim to finish feeling strong rather than chasing a specific time — consistency in training matters far more than race-day pacing strategy for beginners.

How do I convert a 10K time to a half marathon prediction?

A widely used rule of thumb is to multiply your 10K time in minutes by 2.223 to estimate your half marathon potential. For example, a 50:00 10K predicts a half marathon of approximately 50 × 2.223 = 111 minutes (1:51:00). This prediction assumes similar training fitness at both distances and a reasonable long-run base. The Riegel fatigue formula uses pace × (distance ratio)^1.06 for a more precise prediction. Enter your actual 10K finish time as an 'Actual Time → Pace Analysis' input to get the calculator's projections.

Should I run even splits or negative split a half marathon?

Most experienced runners recommend a slight negative split strategy — running the second half 30–60 seconds faster than the first. In practice, this means starting 5–8 seconds per km slower than goal pace for the first 3 km, settling into goal pace from 3–15 km, then allowing your effort to build naturally in the final 6 km. Starting at even effort rather than even pace is also effective since course profiles, crowds, and weather conditions vary throughout a race.

How many weeks should I train for a half marathon?

Beginners with a comfortable 5–10 km base typically need 10–14 weeks of dedicated half marathon training. Intermediate runners (regularly running 25–40 km/week) can peak for a half marathon in 8–10 weeks. Elite runners may focus specifically on a half marathon in a 6–8 week block. A typical training plan includes: 4–5 runs per week, one weekly long run building to 18–19 km, one tempo session, and 2–3 easy recovery runs. The long run is the single most important session for half marathon performance.

Do I need to take gels or nutrition during a half marathon?

For most recreational runners finishing in under 1:45–1:50, the half marathon can be completed without taking on carbohydrate mid-race by relying on the body's glycogen stores. Runners targeting finish times over 1:50+ benefit from taking one gel or 45–60 g of carbohydrate at around 7–10 km, particularly in warm conditions. However, the most important nutrition for a half marathon comes in the 3 days before the race: increase carbohydrate intake slightly and avoid any unusual or heavy meals the night before.

Can my half marathon time predict my marathon time?

A commonly used formula is: Marathon Time ≈ Half Marathon Time × 2.1 (to 2.2). For example, a 1:50:00 half predicts a marathon of roughly 3:51:00–4:02:00. The factor is greater than 2.0 because the additional 21 km in the second half of the marathon introduces glycogen depletion and increasing muscle fatigue. Training specifically for the marathon (particularly runs of 28–35 km and higher total weekly mileage) is required to convert half marathon fitness into a realistic marathon result.

Related Running & Fitness Calculators

Complete your half marathon preparation with these tools:

🏅
Marathon Pace CalculatorPlan your full marathon using the same pace analysis — goal time, required pace, and training zones for 42.2 km.
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Running Pace CalculatorCalculate pace from any distance and time — the companion tool for every training run.
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Running Distance CalculatorFind how far you ran, how long a run will take, or what pace you held in any recent session.
🏃
Running Speed CalculatorConvert between km/h, mph, m/s and pace — with speed zone analysis and race projections.
💗
Target Heart Rate CalculatorDefine heart rate training zones to ensure easy runs are easy and hard sessions hit the right intensity.
💓
Maximum Heart Rate CalculatorCalculate your max HR using 6 validated formulas — the foundation for all HR-based half marathon training.
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VO2 Max CalculatorEstimate your aerobic ceiling and understand what half marathon time your current fitness supports.
🥗
Calorie CalculatorCalculate daily calorie needs adjusted for your half marathon training load and weekly mileage.
👟
Steps & Calories CalculatorConvert step count to calories and distance — useful for tracking all daily movement beyond running.
⚡
TDEE CalculatorFind your Total Daily Energy Expenditure to plan optimal fuelling and recovery nutrition for training.

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