Calculate training pace zones from your threshold pace or a recent race result. Get Jack Daniels or Pfitzinger style zones for structured running training.
Pace zones divide running workouts into ranges linked to different training purposes, from easier aerobic work to faster interval sessions.
This calculator supports Daniels-style and Pfitzinger-style zone frameworks based on threshold pace or a recent race result. Both are commonly used ways to organize running intensity.
Use the pace ranges as training guides and adjust for hills, heat, fatigue, and the workout context.
It is useful for separating easy running from threshold and faster work so sessions are closer to their intended purpose. The zones are starting ranges rather than exact prescriptions, but they make training structure easier to follow consistently.
Jack Daniels Zones (as % of Threshold Pace): • Easy: 65-79% of vVO2max (typically 59-74% of T pace) • Marathon: 80-85% of T pace • Threshold (T): 100% of T pace • Interval (I): ~97-100% vVO2max (faster than T) • Repetition (R): faster than I pace Pfitzinger Zones: • Recovery: 70-76% of LT pace • General Aerobic: 76-84% of LT pace • Endurance: 80-90% of LT pace • Lactate Threshold: 95-100% of LT pace • VO2max: 105-112% of LT pace Threshold from 5K: T pace ≈ 5K pace + 15-20 sec/km Threshold from 10K: T pace ≈ 10K pace + 8-12 sec/km
Result: Easy: 6:20-6:50/km, Marathon: 5:20-5:35/km, Threshold: 5:00/km, Interval: 4:30-4:40/km, Repetition: 4:10-4:20/km
With a 5:00/km threshold pace, easy runs should be 6:20-6:50/km — conversational effort. Marathon pace falls at 5:20-5:35/km. Threshold (tempo) runs at 5:00/km are comfortably hard, sustainable for 20-40 minutes. Intervals at 4:30-4:40/km target VO2max development. Repetitions at 4:10-4:20/km build speed and economy.
Each training zone targets specific physiological adaptations. Easy running builds aerobic base (mitochondrial and capillary density). Marathon pace develops fat oxidation and neuromuscular patterns for race day. Threshold training improves lactate buffering and clearance. Intervals boost VO2max and cardiac output. Repetitions improve running economy and neuromuscular speed.
Research across all endurance sports consistently shows that elite athletes do approximately 80% of their training at easy intensity and 20% at moderate-to-hard intensity. Recreational runners who follow this distribution improve more than those who run at moderate intensity most of the time. The zones in this calculator help you implement this principle.
As fitness improves, your threshold pace gets faster and all zones shift. Recalculate every 6-8 weeks using a recent race or time trial. Avoid the temptation to train in zones based on your goal race pace rather than your current fitness — this leads to overtraining.
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This calculator converts a threshold pace or recent race result into training ranges using two commonly used zone frameworks. The ranges are planning aids for structured training rather than fixed physiological cutoffs. Hilliness, heat, fatigue, and individual recovery can all justify staying toward the easier end of a range.
Threshold (or lactate threshold) pace is the fastest pace you can sustain for approximately 60 minutes in a race. For most runners, it's close to their 10K-15K race pace. It's the intensity where lactate production and clearance are roughly in balance.
From a 5K race: add about 15-20 seconds per km to your 5K pace. From a 10K: add 8-12 sec/km. From a half marathon: your half marathon pace is roughly 5-8% slower than threshold. These are approximations; a dedicated threshold test is more accurate.
Both are physiologically grounded but use different zone structures. Daniels emphasizes five specific training intensities (E, M, T, I, R) tied to specific workout types. Pfitzinger uses overlapping ranges and emphasizes the distinction between recovery and general aerobic running. Both are effective; they use slightly different language for similar concepts.
Easy pace develops aerobic base — mitochondrial density, capillary growth, and fat oxidation — without excessive fatigue. Running easy truly easy allows you to recover between hard sessions and do more overall volume. Most recreational runners run their easy days too fast, which reduces training quality on hard days.
Continuous threshold runs (tempo runs) are typically 20-40 minutes at threshold pace. Threshold intervals (cruise intervals) are 5-15 minute segments with 1-2 minutes recovery, totaling 20-40 minutes of threshold running. Both are effective for improving lactate threshold.
Pace zones are most reliable for structured track and road workouts. Heart rate zones are better for trail running, hilly terrain, and hot weather where pace varies. Ideally, use both: pace for flat workouts and heart rate for variable conditions. Over time, you'll develop a feel for each zone.