Running Interval Pace Calculator
Calculate your optimal interval training paces based on recent race performance. Get target paces for Easy, Marathon, Threshold, VO2max, and Repetition workouts using the physiological velocity model.
Running Interval Pace Calculator
Enter your recent race performance to calculate training paces
Interval Workout Configuration
Enter your race distance and time above to calculate your training paces.
About the Running Interval Pace Calculator
Learn more about the calculator and its creator
Jonas
I have been a runner for over 10 years and I built this calculator to help runners like you and me with training and racing.
How the Running Interval Pace Calculator Works
This calculator uses the physiological velocity model to estimate your training paces based on your recent race performance. The approach is grounded in exercise science research and provides transparent, evidence-based training recommendations.
The Physiological Velocity Model
The key concept is vVO2max—the velocity (running speed) at which you reach your maximum oxygen uptake. By estimating this from your race performance, we can calculate appropriate training paces as percentages of this maximal aerobic velocity.
Step 1: Calculate Race Velocity
vrace = distance / time (m/s)Step 2: Estimate Fraction of VO2max Used
The fraction of VO2max that can be sustained decreases with race duration: - 3-4 min efforts: ~100% of vVO2max - 10 min efforts: ~94% - 30 min efforts: ~86% - 60 min efforts: ~80% - 120+ min efforts: ~74%Step 3: Calculate vVO2max
vVO2max = vrace / fractionStep 4: Calculate Training Paces
Zone Pace = vVO2max × zone percentageTraining Zone Percentages
Each training zone targets specific physiological adaptations at defined percentages of vVO2max:
| Zone | Code | % of vVO2max | Purpose |
|---|---|---|---|
| Easy / Recovery | E | 65-75% | Aerobic base, recovery, fat oxidation |
| Marathon Pace | M | 75-80% | Race-specific endurance, fuel efficiency |
| Threshold / Tempo | T | 83-88% | Lactate threshold, sustained speed |
| VO2max Intervals | I | 95-100% | Maximum aerobic capacity |
| Repetition / Speed | R | 105-110% | Speed, running economy, neuromuscular power |
Recovery Duration Guidelines
Recovery between intervals is based on work-to-rest ratios that allow you to maintain target pace quality:
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E
Easy / Marathon
1:0.25 work:rest ratio (minimal recovery, often continuous)
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T
Threshold
1:0.33 work:rest ratio (e.g., 5 min work, 1:40 jog)
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I
VO2max
1:1 work:rest ratio (equal recovery to maintain quality)
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R
Repetition
1:3 work:rest ratio (full recovery for speed maintenance)
VO2max Estimation
The calculator also estimates your VO2max (ml/kg/min) using the relationship between running velocity and oxygen consumption:
Scientific References
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1
Daniels & Gilbert (1979)
Oxygen Power: Performance Tables for Distance Runners
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2
Jack Daniels' Running Formula
The foundational work on VDOT and training zones
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3
Seiler & Tønnessen (2009)
Intervals, Thresholds, and Long Slow Distance: the Role of Intensity and Duration in Endurance Training
Important: These calculations provide estimates based on typical physiological responses. Individual variation exists, and paces should be adjusted based on perceived effort, heart rate response, and environmental conditions.
Understanding Running Interval Training
Interval training is a cornerstone of effective running programs, allowing athletes to accumulate more time at high intensities than would be possible with continuous running. By alternating between work periods and recovery, runners can target specific physiological adaptations and improve performance across all distances.
What Are Running Intervals?
Running intervals consist of repeated bouts of faster-paced running separated by recovery periods of easy jogging or rest. The structure typically includes:
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1
Work Intervals
The faster-paced portions run at a specific target intensity, typically lasting from 30 seconds to 6 minutes.
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2
Recovery Intervals
Easy jogging or standing rest between work intervals, allowing partial recovery before the next effort.
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3
Total Volume
The number of repetitions and sets that comprise the workout, typically accumulating 10-30 minutes of quality work.
The Five Training Zones Explained
E Easy / Recovery Pace
Easy pace should feel conversational—you can speak in complete sentences without gasping. Running at 65-75% of vVO2max, this zone builds your aerobic foundation, develops capillary networks in muscles, and promotes recovery. Most of your weekly mileage (typically 70-80%) should be at this effort.
M Marathon Pace
Marathon pace sits at 75-80% of vVO2max—faster than easy running but sustainable for 2-4 hours. This zone improves fuel efficiency and teaches your body to conserve glycogen while running at a moderate-hard effort. Marathon pace workouts help bridge the gap between easy aerobic running and threshold work.
T Threshold / Tempo Pace
Threshold pace (83-88% of vVO2max) is "comfortably hard"—you can speak only in short phrases. This intensity corresponds closely to your lactate threshold, the point where lactate production begins to exceed clearance. Training here improves your ability to sustain faster paces and pushes your threshold higher.
I VO2max Intervals
VO2max intervals (95-100% of vVO2max) are hard efforts sustainable for 3-6 minutes. This zone maximizes the time your cardiovascular system operates at peak capacity, driving adaptations in heart stroke volume, oxygen delivery, and mitochondrial density. Classic workouts include 5×1000m or 6×800m with equal recovery.
R Repetition / Speed Pace
Repetition pace (105-110% of vVO2max) develops speed, running economy, and neuromuscular coordination. These short, fast intervals (typically 200-400m) with long recovery improve your ability to run efficiently at high speeds. The extended rest allows you to maintain excellent form and speed across all repetitions.
Benefits of Interval Training
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1
Improved VO2max
High-intensity intervals are the most effective way to increase your maximum oxygen uptake, a key determinant of distance running performance.
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2
Higher Lactate Threshold
Threshold intervals push your lactate threshold to higher speeds, allowing you to race faster before fatigue sets in.
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3
Better Running Economy
Speed work improves neuromuscular efficiency, reducing the oxygen cost of running at any given pace.
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4
Mental Toughness
Practicing sustained hard efforts builds the mental skills to push through discomfort in races.
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5
Time Efficiency
Intervals allow you to achieve significant training stimulus in less time compared to easy running alone.
Sample Interval Workouts by Goal
| Race Goal | Zone Focus | Example Workout |
|---|---|---|
| 5K | I + R | 6 × 1000m at I pace, 3:00 jog; or 10 × 400m at R pace |
| 10K | I + T | 5 × 1200m at I pace; or 4 × 2000m at T pace |
| Half Marathon | T + M | 3 × 3000m at T pace; or 5 × 1 mile at T pace |
| Marathon | M + T | 8 miles at M pace; or 2 × 4 miles at M-T pace |
How to Structure Your Training Week
A well-balanced training week for most distance runners includes:
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1
1-2 Quality Sessions
Interval workouts at T, I, or R pace, with at least 48 hours between hard sessions.
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2
1 Long Run
Easy to moderate pace, building endurance and aerobic capacity.
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3
3-4 Easy Runs
Recovery and base-building at E pace, comprising the majority of weekly volume.
Pro Tip: Consistency trumps intensity. It's better to complete moderate workouts week after week than to push too hard and need extra recovery time. Start conservatively with interval paces and adjust based on how you feel.
Common Interval Training Mistakes
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✕
Running Intervals Too Fast
Starting too fast leads to declining pace and quality in later reps. Stick to prescribed paces.
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✕
Skipping Recovery
Cutting recovery short compromises the quality of subsequent intervals. Trust the rest periods.
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✕
Too Much Volume
More intervals aren't always better. Quality over quantity—stop when form deteriorates.
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✕
Ignoring Easy Days
Hard-easy balance is essential. Running too fast on recovery days undermines adaptation.
Getting Started with Intervals
If you're new to interval training, follow these guidelines for a successful introduction:
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✓
Build a Base First
Establish 3-4 weeks of consistent easy running before adding intensity.
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✓
Start with Threshold Work
T pace is easier to control than I or R pace. Begin with tempo runs before adding faster intervals.
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✓
Keep Volume Low Initially
Start with 10-15 minutes of quality work and gradually increase over weeks.
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✓
Warm Up Properly
10-15 minutes of easy running plus dynamic stretches before hard efforts.
Frequently Asked Questions
vVO2max (velocity at VO2max) is the running speed at which you reach your maximum oxygen uptake. It's a key metric for setting interval paces because it represents the speed you can sustain for about 6-10 minutes at maximum aerobic effort. Training at specific percentages of vVO2max targets different physiological adaptations.
The paces are estimates based on well-established exercise physiology research. They're most accurate when using a recent race time (within 4-8 weeks) where you gave a full effort. Factors like fatigue, weather, and terrain can affect how these paces feel during actual training.
Races between 3K and half marathon typically provide the most reliable predictions. 5K and 10K races are particularly good reference points. Shorter races (1500m-mile) or longer ones (marathon) can work but may be slightly less accurate for interval pace calculations.
Threshold intervals are run at lactate threshold pace (about 83-88% of vVO2max), sustainable for 20-60 minutes in a race. They improve your ability to sustain fast paces. VO2max intervals are faster (95-100% of vVO2max), sustainable for only 3-6 minutes, and develop your maximum aerobic capacity.
Recovery duration depends on the workout goal. Easy and Marathon pace workouts use minimal recovery (20-25% of work time). Threshold intervals use 1:0.33 work-to-rest. VO2max intervals typically use 1:1 work-to-rest. Repetition intervals need the most recovery (1:3) to maintain speed and form quality.
Repetition pace intervals (105-110% of vVO2max) are short, fast efforts with full recovery. They develop running economy, neuromuscular coordination, and speed. Typical workouts include 200m-400m repeats with 2-4 minutes rest between each.
Most runners benefit from 1-2 quality interval sessions per week, with easy running between hard days. Beginners should start with one session weekly. Advanced runners may do 2-3, but more isn't always better. Allow 48-72 hours recovery between hard interval sessions.
Yes, a time trial can work well if you give a genuine maximal effort. Run it on a flat, measured course in good conditions. 5K time trials on a track are particularly useful. The effort should feel like race-day intensity for accurate pace predictions.
Easy pace should truly feel easy - you should be able to hold a conversation. Many runners train too fast on easy days, which compromises recovery and limits the benefits of hard training. Trust the 65-75% vVO2max range for aerobic development without excessive fatigue.
The zones (E, M, T, I, R) are similar to Daniels' training zones but use a transparent physiological velocity model. The percentages are based on vVO2max research and produce comparable results to VDOT tables for most runners. Small differences may exist at the extremes of fitness levels.
Yes, environmental factors affect performance. In heat (above 60°F/15°C), slow paces by 1-3% per 10°F/5°C. At altitude, reduce intensity by 3-6% per 1000m/3000ft elevation. For hills, focus on effort rather than pace - maintain the same perceived exertion as flat intervals.
If paces feel too hard, your race time input may be outdated, or you may be fatigued. Try using a more recent or conservative race time. Also ensure adequate recovery between workouts, proper nutrition, and good sleep. It's better to run slightly slower with good form than struggle through at target pace.
What is vVO2max and why is it important for interval training?
How accurate are the calculated interval paces?
What race distance should I use for the best results?
What's the difference between Threshold and VO2max intervals?
How long should recovery be between intervals?
What are Repetition (R) pace intervals used for?
How often should I do interval workouts?
Can I use a time trial instead of a race?
Why are my Easy pace recommendations slower than I expected?
How do these zones compare to Jack Daniels' VDOT paces?
Should I adjust paces for heat, altitude, or hills?
What if I can't complete intervals at the calculated pace?
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