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Marathon Pace Basics

A marathon is 26.2 miles (42.195 km). Your required pace is simply your goal finish time divided by the distance. At 10:00/mile average pace, you finish in 4 hours 22 minutes. At 9:09/mile, you break 4 hours. At 7:38/mile, you break 3:20.

The critical nuance: marathon pace is not a flat number you run every mile. Elevation, temperature, fatigue curves, and mid-race fuelling all cause natural pace variation. The goal is to run the right average — which requires a deliberate strategy, not just a GPS watch target.

Get your exact required pace per mile or per kilometre instantly with our pace calculator — enter your goal time and distance and it outputs your required split.

"The most common marathon mistake is running the first 13.1 miles to a finish time — not a process. Going out 10 seconds per mile too fast in the first half costs 2–4 minutes in the second half. Negative splits are faster in practice, not just in theory."

Finish Time vs. Required Pace

Reference chart for common goal times. Use our pace calculator for any custom target.

Goal Finish Time	Pace per Mile	Pace per KM	Half Split
3:00:00	6:52/mi	4:16/km	1:29:35
3:15:00	7:26/mi	4:37/km	1:37:05
3:30:00	8:01/mi	4:58/km	1:44:35
4:00:00	9:09/mi	5:41/km	1:59:35
4:30:00	10:19/mi	6:24/km	2:14:35
5:00:00	11:27/mi	7:07/km	2:29:35
5:30:00	12:35/mi	7:49/km	2:44:35

Training Pace Zones

Marathon training involves multiple pace zones, each serving a different physiological purpose. Running everything at race pace is one of the most common training mistakes — it accumulates fatigue without building the aerobic base that makes race pace sustainable.

Zone	% of Marathon Pace	Heart Rate % Max	Purpose
Easy / Recovery	+20–30% slower	60–70%	Aerobic base, recovery, fat adaptation
Long Run	+10–20% slower	65–75%	Endurance, glycogen depletion training
Marathon Pace	Race pace	75–85%	Race-specific economy and mental rehearsal
Tempo / Threshold	5–10% faster	85–90%	Lactate clearance, race pace feel easier
Interval / Speed	15–25% faster	90–95%	VO2max, running economy

Elite marathon programs run 70–80% of total mileage in easy/long-run zones. The counterintuitive truth: slowing down on easy days makes you faster on race day by building aerobic capacity without accumulating the fatigue that suppresses adaptation.

Use our half marathon pace calculator to set your tempo and threshold training targets — half marathon race pace closely approximates the lactate threshold zone for full marathon training.

Predicting Marathon Time from Half Marathon

Your recent half marathon time is the most reliable predictor of marathon potential, assuming specific marathon training has been completed. The most commonly used formulas:

Pete Riegel formula: Marathon time = Half time × 2 × (26.2/13.1)^1.06. For a 1:55 half, predicted full = ~4:02.
Practical multiplier: Double your half marathon time, then add 10–20 minutes for a well-trained runner in good conditions. Add 15–30 minutes for first-time marathoners or those without 16+ weeks of marathon-specific training.
Fatigue factor: Marathons involve glycogen depletion in a way halfs do not. Pace prediction assumes fuelling strategy is executed correctly. Poor fuelling can add 20–45 minutes regardless of fitness.

Race Day Pacing Strategy

Three approaches — only one is consistently optimal:

Even splits (recommended)

Best approach

Run every mile at the same target pace. Physiologically the most efficient — conserves glycogen and avoids early lactate accumulation. Difficult psychologically in the first 10 miles when adrenaline makes race pace feel easy.

Negative splits (also excellent)

Elite approach

Run the second half 1–3 minutes faster than the first. Allows warm-up, checks conditions early, and leverages fresher legs later. World record performances are almost universally negative split. Requires exceptional discipline in miles 1–13.

Positive splits (avoid)

Avoid

Going out too fast and slowing in the second half. Accounts for most "bonking" and "hitting the wall" experiences. Even 10–15 seconds per mile too fast in miles 1–10 triggers early glycogen depletion and pace collapse after mile 18.

Practical execution: In the first 3 miles, aim to run 5–10 seconds per mile slower than goal pace. Adrenaline and crowd energy will make goal pace feel trivial — trust the watch, not your perceived effort.

Calories Burned Running a Marathon

A rough rule: running burns approximately 100 calories per mile for a 155 lb (70 kg) runner. Lighter runners burn less; heavier runners burn more. A full marathon at this bodyweight burns ~2,620 calories.

The glycogen constraint: the body can store ~2,000 calories of glycogen (roughly 18–20 miles of marathon-pace running). Miles 20–26.2 require either supplemental carbohydrate (gels, chews) or fatty acid oxidation — which is slower and why pace typically falls in the final miles without fuelling.

Take 60–90g of carbohydrate per hour starting at mile 4–5, not when you feel hungry
Practice fuelling strategy in long training runs — the gut can be trained to absorb carbs at higher rates
Hydrate with electrolytes, not just water — hyponatremia (dilutional low sodium) is a real risk at finish times over 5 hours

Calculate your exact calorie burn for any distance with our calories burned calculator.

Pacing Mistakes That Cost Time

Going out too fast

The most universal error. Mile 1 excitement and adrenaline make goal pace feel effortless. Running 15 sec/mile too fast for the first 8 miles triggers glycogen depletion 4–6 miles earlier than planned.

Treating the half split as the race

Many runners push to a strong half split and then struggle to hold it. The marathon starts at mile 20. Everything before that is setup. A great half split executed too aggressively is a liability, not an asset.

Skipping fuel until feeling depleted

By the time you feel glycogen depleted (the "wall"), it is too late for gels to rescue the pace. Digestion takes 15–20 minutes. Fuel early, on schedule, whether hungry or not.

Undertrained but correctly paced early

Correct pacing cannot compensate for insufficient training. If weekly mileage peaked under 35–40 miles and you run race pace perfectly, the body simply does not have the aerobic base for miles 20–26.

Not accounting for course elevation

Boston and other hilly courses require pace adjustments — slower on uphills (maintain effort, not pace) and conservative on early downhills (quad-damaging eccentric load). A flat course pace plan fails on a hilly course.

Marathon Pace FAQs

What is a good first marathon time?

For most first-time marathoners, finishing between 4:00 and 5:30 is typical. The goal for a first marathon should be completing it with a strong second half — time improvement comes in subsequent races as training base develops.

How accurate is pace per mile in predicting finish time?

Very accurate if pace is held steady. The risk is pace variability — most runners run the first half 3–8% faster than the second, which shifts actual finish time 5–15 minutes beyond the even-split projection.

Should I use a GPS watch or run by feel?

Use a GPS watch for the first half to prevent going out too fast, then shift to perceived effort for the second half. GPS drift (especially in city canyons) can create false data; perceived effort paired with heart rate monitoring is more reliable late in the race.

How do I train for my first sub-4 hour marathon?

Sub-4 requires a 9:09/mile average. Key training benchmarks: comfortable 10-mile long run at 10:30–11:00/mile, tempo runs of 6–8 miles at 8:30–9:00/mile, and peak weekly mileage of 40–45 miles. A 16–20 week build is standard.

Does weather affect marathon pace?

Significantly. For every 10°F above 55°F (13°C), expect 1–3% pace slowdown. At 70°F (21°C), adjust goal pace 3–5% slower than training-based projections. Racing in heat without adjusting guarantees a blown second half.

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