What is a good half marathon time?

Half marathon finish time benchmarks by sex: Male: - World class / elite: under 1:03 - Competitive club: 1:03–1:15 - Advanced: 1:15–1:30 - Intermediate: 1:30–1:45 - Recreational: 1:45–2:00 - Beginner: 2:00–2:30 - Just finished: 2:30+ Female: - World class / elite: under 1:09 - Competitive club: 1:09–1:22 - Advanced: 1:22–1:40 - Intermediate: 1:40–1:55 - Recreational: 1:55–2:15 - Beginner: 2:15–2:45 - Just finished: 2:45+ World records: - Male: 57:31 (Jacob Kiplimo, later beaten by Kibel — check for latest) - Female: 1:02:52 (Letesenbet Gidey, 2021) Median half marathon finish times (large races like NYC Half): - Male: approximately 2:05 - Female: approximately 2:22 The median is much slower than most people expect — the majority of half marathon finishers are recreational runners. A 2:00 finish puts you faster than roughly half of all finishers.

How do I train for a half marathon?

Half marathon training requires building both aerobic base and the specific endurance to sustain HM race pace for ~1-3 hours. Key training components: 1. Long run (most important session): - Build to 18-22 km / 11-14 miles over 12-16 weeks - Run at easy pace (1:30-2:00 per km slower than HM pace) - The long run builds mitochondrial density, fat oxidation, and mental toughness - Include 2-4 km at HM pace in final long runs to practise race effort 2. Tempo / threshold runs: - 20-35 min at lactate threshold (approx HM pace + 12-15 sec/km) - Or cruise intervals: 3 × 10 min at threshold with 90 sec recovery - Frequency: once per week - Purpose: raises the pace you can sustain aerobically 3. Easy runs: - 4-5 days per week at conversational pace - This is your aerobic base — the foundation everything else rests on - Most beginners make the mistake of running these too fast (grey zone) 4. Optional interval sessions: - 4-6 × 1000m at 5K effort with 90 sec recovery - Only useful once you have a solid base (8+ weeks of consistent running) Sample 12-week build (intermediate): Weeks 1-4: Establish base. 35-45 km/week. Long run 12-14 km. Weeks 5-8: Build. 45-55 km/week. Add tempo. Long run 15-18 km. Weeks 9-11: Peak. 55-65 km/week. Long run 19-22 km. Include HM pace sections. Week 12: Taper. Reduce volume 40-50%, maintain intensity. Race on weekend.

How accurate is the marathon prediction from half marathon time?

Predicting marathon time from half marathon performance using Riegel's formula: Marathon time ≈ HM time × (42.195 / 21.0975)^1.06 ≈ HM time × 2.199 Example: 1:45:00 HM → 1:45 × 2.199 = 3:50 marathon (Riegel). But this is often optimistic. Why the prediction often over-estimates marathon fitness: 1. Long-run specific fatigue: the marathon's final 10-15 km involves a level of glycogen depletion and muscle breakdown not experienced in a half marathon — no amount of shorter race training replicates this 2. Fuelling complexity: the half marathon requires minimal fuelling; the marathon requires near-perfect carbohydrate intake 3. Training specificity: a runner peaking for a half marathon and running a marathon is under-trained for that distance More realistic marathon predictions from HM: - Well-trained marathoners (16+ week specific marathon training, 20+ mile long runs): HM × 2.10-2.15 - Average runners (some long-run training): HM × 2.20-2.30 - Under-trained or first marathon: HM × 2.40-2.60+ The 2:10 multiplier applies to runners who: - Have completed 3+ long runs of 30+ km in the training cycle - Have practised race-day fuelling - Have run at least 2 previous marathons Best approach: use the Riegel prediction as an optimistic ceiling, then adjust downward based on your longest training run, fuelling experience, and race experience.

What pace should I target on race day?

Half marathon race pacing strategy: Even split (recommended for most runners): - Run each kilometre at the same target pace throughout - For 1:45:00 goal: each km at 4:59 — every single one - Benefit: physiologically optimal — avoids early lactate accumulation - Challenge: first km feels easy, requires discipline Negative split (optimal for experienced runners): - First half: 1-3 sec/km slower than target - Second half: 1-3 sec/km faster than target - For 1:45:00: first 10km at 5:02-5:03/km, second 11km at 4:56-4:57 - Benefit: preserves glycogen and reduces early fatigue debt - Most world records are run with negative splits Common mistakes: 1. Starting too fast (most common): - Race excitement and crowd energy push you to run 15-30 sec/km faster than goal pace in km 1-3 - You will pay for this in km 15-20 — the wheels come off - Solution: set a pace alert on your watch; let everyone pass you in the first 2 km 2. 'Comfortable' starting pace: - Goal race pace should feel uncomfortable from km 5 onward - If it feels easy at halfway, it's probably not fast enough - Target a pace that demands focused effort without being desperate 3. Ignoring kilometre splits: - Most GPS watches are accurate to ±10-15 metres per km - Check your split at every km marker and adjust immediately - A 5-10 sec error per km compounds to 1-2 min over 21 km Practical tip: pin your target per-km split on your race bib or write it on your wrist. Reference it at every km marker.

What is the difference between half marathon pace and tempo pace?

Half marathon pace and tempo (lactate threshold) pace are closely related but distinct: Tempo / Lactate Threshold pace: - The fastest pace you can sustain for approximately 40-60 minutes - Physiologically: the point where lactate production equals lactate clearance - Feel: comfortably hard — can speak a few words but not sentences - Typical paces: 10-15 sec/km faster than marathon pace, 5-15 sec/km slower than half marathon pace Half Marathon pace: - Typically 10-20 sec/km faster than tempo pace for most runners - HM race is run at 85-92% of VO2 max for most runners - You are accumulating lactate slowly — this is what limits half marathon performance - By km 18-20, most runners are working near lactate threshold Approximate relationships (1:45 HM example, 4:59/km): - Easy pace: ~6:29/km - Tempo pace: ~5:11/km (4:59 + 0:12) - HM race pace: 4:59/km - 10K race pace: ~4:45/km - 5K race pace: ~4:39/km Why the distinction matters for training: - Tempo runs improve your ability to sustain HM pace: the closer your threshold is to HM pace, the less effort HM pace requires - Most HM training plans include 1 tempo session per week to specifically raise this threshold - Running too much mileage at HM pace (race pace) in training creates unnecessary fatigue without the threshold-raising benefit of tempo runs

How long does it take to train for a half marathon?

Training timelines by starting fitness level: Complete beginner (never run before, or less than 1 month of running): - Timeline: 20-24 weeks - Phase 1 (weeks 1-8): Run/walk intervals, build to 30 min continuous running - Phase 2 (weeks 9-16): Build to 10-12 km long run, 3-4 days/week running - Phase 3 (weeks 17-24): Half marathon specific training — 18-22 km long runs, tempo sessions Casual runner (can run 5K comfortably, runs 1-2x/week): - Timeline: 12-16 weeks - Weeks 1-4: Increase frequency to 3-4 days/week, build long run to 10 km - Weeks 5-10: Weekly tempo, long run builds to 16-18 km - Weeks 11-14: Peak week with 20+ km long run, 2-week taper Active runner (runs 5K-10K regularly, 3+ days/week): - Timeline: 10-12 weeks - Can begin with 45-55 km/week base - Focus: quality sessions (tempo, HM pace work), long run progression to 22 km - 1-2 week taper before race Key milestones before race day: 1. Must complete at least one long run of 18+ km in the 4 weeks before the race 2. Should have run at HM race pace for at least 5-8 km in training 3. Should have practised race-day fuelling (gels/drinks) on long runs 4. Must be injury-free in the 2 weeks before the race

Half Marathon Pace Calculator — Splits & Training Paces

The Half Marathon Pace Calculator converts between finish time and running pace for the 21.0975 km (13.1094 mile) half marathon distance. Enter a finish time (H:MM:SS) or pace (min/km or min/mile) to get: pace in both km and mile units simultaneously, speed in km/h, a 7-level fitness category (World Class to Just Finis..

YOUR HALF MARATHON

ENTER YOUR

FINISH TIME

HOURS

MINUTES

SECONDS

YOUR HALF MARATHON

FINISH TIME

1:45:00

PACE / km

4:59

PACE / mile

8:01

SPEED

12.1

km/h

LEVEL (MALE)

Recreational

1:45–2:00 — regular runner

World record: 57:31 (Kibel 2024) — you are at 54.8% of WR pace

HALF MARATHON LEVELS (MALE)

World Classsub 1:03:00

Elite1:03:00–1:15:00

Advanced1:15:00–1:30:00

Intermediate1:30:00–1:45:00

Recreational1:45:00–2:00:00

Beginner2:00:00–2:30:00

Just Finished2:30:00–166:39:00

5 KM CHECKPOINT SPLITS

TRAINING PACES (derived from your HM pace)

Zone	Pace / km	Purpose
Easy / Recovery	6:29	Conversational, Z1-Z2, base building (most volume)
Moderate / Steady	5:39	Comfortably hard, Z3, medium-long runs
Tempo / Threshold	5:11	Lactate threshold, Z4, 20-40 min sustainable
Half Marathon Pace	4:59	Goal race effort — your HM pace
5K Equivalent	4:39	VO2 max effort, 800m-1600m intervals
Interval (I-pace)	4:29	Hard intervals, VO2 max, 400m-1000m repeats

RACE PREDICTIONS (Riegel formula)

Race	Predicted Time	Pace / km
🏃 5K	22:50	4:34
🏃 10K	47:35	4:46
🏃 Half Marathon	1:45:00	4:59
🏅 Marathon	3:38:55	5:11

Riegel: T2 = T1 × (D2 / 21.0975)^1.06. Marathon prediction assumes equivalent aerobic fitness & long-run training.

Created with ❤️ byeaglecalculator.com

HOW TO USE

1
Select your unit system (metric km or imperial miles) and sex. Sex is used for the fitness category benchmarks — male and female runners have different time ranges for each level. Both unit options always show pace in both km and mile simultaneously in the results panel.
2
Choose whether to enter a finish time (H:MM:SS with three separate inputs) or a running pace (M:SS per km or per mile). In time mode, use the quick-select buttons for common half marathon targets from 1:15 to 3:00. In pace mode, quick-select buttons show the corresponding pace for common finish times.
3
Read your results: finish time shown in large orange numerals, pace in both km and mile units, speed in km/h, your fitness category from a 7-level scale (World Class to Just Finished), and a world record comparison showing what percentage of world record pace you are running at — male WR 57:31 (Kibel 2024) and female WR 1:02:52 (Gidey 2021).
4
Check the splits chart — checkpoint times plotted as a line chart with markers at each 5km split (5, 10, 15, 20 km and the finish at 21.0975 km) in km mode, or mile splits in mile mode. Each marker shows the cumulative elapsed time at that point for perfectly even pacing.
5
Review training paces and race predictions. The training paces table shows 6 zones derived from your HM pace using Jack Daniels methodology: Easy, Moderate, Tempo, HM Race pace, 5K equivalent, and Interval pace — each with a description of its purpose. The race predictions table uses Riegel's formula to project 5K, 10K, and marathon finish times from your half marathon performance.

WORKED EXAMPLE

Half Marathon Pace Calculator — worked example: INPUT: 1:45:00 finish time STEP 1 — Pace: HM distance = 21.0975 km Total time = 1h 45m = 105 minutes = 6,300 seconds Pace = 105 min / 21.0975 km = 4.9764 min/km = 4:59/km Speed = 60 / 4.9764 = 12.06 km/h Pace in miles = 4.9764 × 1.60934 = 8.009 min/mile = 8:01/mile STEP 2 — Splits (even pacing at 4:59/km): 5 km: 4:59 × 5 × 60 = 1,493 sec = 24:53 10 km: 4:99 × 10 × 60 = 2,986 sec = 49:46 15 km: 4,478 sec = 1:14:38 20 km: 5,971 sec = 1:39:31 21.0975: 4:99 × 21.0975 × 60 = 6,300 sec = 1:45:00 STEP 3 — Training paces: Easy: 4:59 + 1:30 = 6:29/km Moderate: 4:59 + 0:40 = 5:39/km Tempo: 4:59 + 0:12 = 5:11/km HM Race: 4:59/km 5K equiv: 4:59 - 0:20 = 4:39/km Interval: 4:59 - 0:30 = 4:29/km STEP 4 — Race predictions (Riegel: T2 = T1 × (D2/21.0975)^1.06): 5K: 6300 × (5/21.0975)^1.06 = 6300 × 0.2163 = 1,363 sec = 22:43 10K: 6300 × (10/21.0975)^1.06 = 6300 × 0.4437 = 2,795 sec = 46:35 Marathon: 6300 × (42.195/21.0975)^1.06 = 6300 × 2.199 = 13,853 sec = 3:50:53 WORLD RECORD COMPARISON (male): WR: 57:31 = 3,451 sec 1:45:00 = 6,300 sec Percentage: 3451/6300 = 54.8% of WR pace

REFERENCE FORMULAS

FORMULA REFERENCE TABLE

Name	Formula	Description
HM distance	21.0975 km = 13.1094 miles	Official IAAF measurement. Exactly half of the marathon (42.195 km).
Pace from finish time	Pace (min/km) = finish_time(min) / 21.0975	1:45:00 = 105 min. 105 / 21.0975 = 4.976 min/km = 4:59/km.
Finish from pace	Time (sec) = pace(min/km) × 21.0975 × 60	4:59/km × 21.0975 × 60 = 6,300 sec = 1:45:00.
Speed from pace	Speed (km/h) = 60 / pace (min/km)	4:59/km = 60 / 4.976 = 12.06 km/h.
Pace (km to mile)	min/mile = min/km × 1.60934	4:59/km × 1.60934 = 8:01/mile.
Riegel race predictor	T2 = T1 × (D2 / 21.0975)^1.06	Predicts race times at other distances. Marathon: 1:45 × (42.195/21.0975)^1.06 = 3:38:55.
Easy training pace	HM pace + 1:30/km (approx)	Most training volume. Fully conversational. Example: 4:59 HM pace → ~6:29 easy.
Tempo pace	HM pace + 0:12/km (approx)	Lactate threshold — slightly faster than HM race pace. Sustainable for 20-40 min.
5K equivalent pace	HM pace - 0:20/km (approx)	Predicted 5K race pace based on HM performance. Used for interval sessions.

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Last updated: April 29, 2026 · HM = 21.0975 km (IAAF) · Riegel (1977) · Jack Daniels VDOT training paces