Daniels VDOT Paces for a 3:15 Marathon PR: Full Zone Breakdown

Jack Daniels' VDOT system maps a known race time onto a full set of training paces. The math is more conservative than Riegel and explicitly anchored to running economy and VO2max physiology^[1]. For a 3:15 marathon PR — a strong recreational runner's target — the system returns the full zone set on one page.

The scenario

A trained marathoner with a recent flat-course PR of 3:15:00 (195 minutes for 42.195 km, 4:37/km average pace). The runner is between training cycles and wants the Daniels zones to use as the structure for the next 12-week build.

What the calculator returns

Running the inputs through the Run Training Paces Calculator:

# run-training-paces-calculator (computed live from /engines/run-training-paces-calculator.js)
Engine input
  distance              = marathon
  race_time_minutes     = 195
  race_time_seconds     = 0

Engine output
  vdot                  = 48.7
  inputRaceDistanceMeters= 42195
  inputRaceTimeSeconds  = 11700
  inputPacePerKmSeconds = 277
  zones[0].zone         = E
  zones[0].label        = Easy / Long Run
  zones[0].description  = Conversational pace for aerobic base and recovery. Use for most training volume.
  zones[0].pacePerKmSeconds= 325
  zones[0].pacePerMileSeconds= 523
  zones[0].effortPercent= 67
  zones[1].zone         = M
  zones[1].label        = Marathon Pace
  zones[1].description  = Comfortably hard. Race-specific feel for marathon training runs.
  zones[1].pacePerKmSeconds= 285
  zones[1].pacePerMileSeconds= 458
  zones[1].effortPercent= 79
  zones[2].zone         = T
  zones[2].label        = Threshold / Tempo
  zones[2].description  = Comfortably hard sustained effort. Improves lactate threshold. Max 20 min continuous.
  zones[2].pacePerKmSeconds= 266
  zones[2].pacePerMileSeconds= 428
  zones[2].effortPercent= 86
  zones[3].zone         = I
  zones[3].label        = Interval / VO₂max
  zones[3].description  = Hard 3–5 min repeats near VO₂max. Builds aerobic power. Typical rep: 800m–1200m.
  zones[3].pacePerKmSeconds= 240
  zones[3].pacePerMileSeconds= 386
  zones[3].effortPercent= 98
  zones[4].zone         = R
  zones[4].label        = Repetition / Speed
  zones[4].description  = Short fast reps (200m–400m) with full recovery. Develops economy and speed.
  zones[4].pacePerKmSeconds= 218
  zones[4].pacePerMileSeconds= 350
  zones[4].effortPercent= 110
  equivalentRaceTimes[0].distance= 1,500m
  equivalentRaceTimes[0].distanceMeters= 1500
  equivalentRaceTimes[0].predictedSeconds= 332
  equivalentRaceTimes[1].distance= 1 Mile
  equivalentRaceTimes[1].distanceMeters= 1609.34
  equivalentRaceTimes[1].predictedSeconds= 358
  equivalentRaceTimes[2].distance= 5K
  equivalentRaceTimes[2].distanceMeters= 5000
  equivalentRaceTimes[2].predictedSeconds= 1224
  equivalentRaceTimes[3].distance= 10K
  equivalentRaceTimes[3].distanceMeters= 10000
  equivalentRaceTimes[3].predictedSeconds= 2537
  equivalentRaceTimes[4].distance= Half Marathon
  equivalentRaceTimes[4].distanceMeters= 21097.5
  equivalentRaceTimes[4].predictedSeconds= 5620
  equivalentRaceTimes[5].distance= Marathon
  equivalentRaceTimes[5].distanceMeters= 42195
  equivalentRaceTimes[5].predictedSeconds= 11700

Five training zones plus a six-distance equivalence table. The 4:45/km marathon pace zone in the table is the planned race pace for the next cycle; the 4:26/km threshold pace is what a 1-hour race would feel like.

Reading the zones

Each zone has a specific physiological target:

Zone   Pace      Stimulus                  Typical session
─────────────────────────────────────────────────────────────────
E      5:25/km   Aerobic capillarization   Long runs, recovery jogs
M      4:45/km   Marathon-specific         Marathon-paced workouts
T      4:26/km   Lactate threshold         15 to 25 min steady tempo
I      4:00/km   VO2max                    3 to 5 min repeats
R      3:38/km   Economy + speed           200 to 400 m repeats

Daniels weekly time distribution suggestion (build phase):
  E       70 to 80%
  M       5 to 10%   (marathon-paced sessions)
  T       8 to 12%   (one tempo per week)
  I       3 to 8%    (one VO2 session per week)
  R       1 to 3%    (light strides, drills)

The Easy pace (5:25/km) is meaningfully slower than the marathon pace (4:45/km). Most recreational runners drift their easy days into Zone M territory, which over-trains lactate-clearance physiology and under-trains the aerobic base. Hold the Easy days slow.

Where the VDOT system breaks

Marathon-specific endurance is not captured. The VDOT assumes the runner has the aerobic base to actually deliver the predicted marathon time. A 5K PR of 20:24 produces the same VDOT 48.7, but a runner with that 5K time and only 30 km/week training volume will not run a 3:15 marathon. The system predicts physiological capacity; it does not predict whether the runner has built marathon-specific endurance.

Heat and elevation adjustments. Daniels paces assume flat dry conditions at sea level. Each 5°C above 18°C adds 5 to 8 seconds per kilometer to the marathon and threshold paces; each 500 m of altitude above 1500 m adds another 2 to 4 seconds/km. Use the published paces as the baseline and adjust race-day execution against conditions.

Older runners. The VDOT-to-pace relationship was largely fit on athletes under 40. Masters runners (45+) typically need 3 to 5 seconds/km slower than the table at Threshold and Interval paces to avoid accumulated fatigue across the week. Easy and Marathon paces hold well.

A 12-week marathon build against these zones

Translating the zones into a representative weekly structure for a 12-week build toward a sub-3:15 attempt:

Mon  Easy run, 60 min @ 5:25/km                     ≈ 11 km
Tue  Quality day:
       3 km warm-up E
       4 × 1000 m @ I (4:00/km) with 400 m E jog
       3 km cool-down E
                                                    ≈ 13 km
Wed  Easy run + drills, 50 min @ E pace             ≈ 9 km
Thu  Tempo day:
       3 km warm-up E
       6 km @ T (4:26/km)
       3 km cool-down E
                                                    ≈ 12 km
Fri  Rest or 30 min E shake-out                     ≈ 5 km
Sat  Long run with M-paced finish:
       18 km @ E (5:25/km) + 6 km @ M (4:45/km)
                                                    ≈ 24 km
Sun  Easy recovery, 40 min @ slow E                 ≈ 7 km

Weekly total                                        ≈ 81 km
Weekly E/M/T/I/R split (by time)                    78 / 7 / 7 / 7 / 1%

The weekly volume of ~80 km is in the band that supports a 3:15 marathon at this VDOT; serious sub-3 attempts typically require 95 to 130 km/week. Below 60 km/week, the predicted marathon time stalls regardless of how well the quality sessions go — endurance volume is the binding constraint, not VO2max.

Pace targets by week of the build

The zone paces stay fixed across the build; what changes is the duration of work at each pace. A 12-week structure typically scales tempo and interval work upward:

Build phase   Weekly km   Tempo work        Interval work    Long run
─────────────────────────────────────────────────────────────────────────
Wk 1 – 3       60 to 70    4 × 800 m T       5 × 800 m I      18 km
Wk 4 – 6       70 to 80    2 × 3 km T        6 × 800 m I      22 km
Wk 7 – 9       80 to 90    6 km T            4 × 1000 m I     28 km + 6 M
Wk 10 – 11     85           Race-pace MP     reduce volume    32 km easy
Wk 12          taper        Strides only     none             8 km easy

Race week:
  Mon  4 km Z1 shakeout
  Tue  10 × 200 m strides @ R, 200 m E rest
  Wed  Off
  Thu  4 km Z1 + 4 × 100 m strides
  Fri  Off
  Sat  Race

The taper drops weekly volume by 50 to 60% in the final two weeks while keeping the intensity touches (strides, short threshold) to maintain neural sharpness. The race-week template assumes the race is on a Saturday; shift the days for Sunday races.

Cross-checking against Riegel

The Riegel formula and VDOT both predict equivalent race times from a known result. For a 3:15 marathon, Riegel predicts a 1:33:18 half marathon at 1.06 exponent, against VDOT's 1:33:40 — agreeing within 22 seconds. The two systems generally converge for marathon-to-half-marathon predictions and diverge for 5K-to-marathon predictions where Riegel's exponent does not adequately account for marathon-specific decay.

Cross-check with the Race Time Predictor (Riegel-based) and the Running Pace Calculator for arbitrary pace/time/distance conversions.

Related tools and follow-ups

• Run Training Paces Calculator — the engine used here.
• Race Time Predictor — Riegel-based cross-check on equivalent race times.
• Running Pace Calculator — convert between pace, time, and distance for any interval.

For broader context: How to train for a 5K, Race time prediction: VDOT vs Riegel failure modes, and Marathon taper volume reduction curve cover the broader training-block framework.

FAQ

What is the VDOT for a 3:15 marathon? 48.7. The engine returns the VDOT from a 195-minute marathon at 4:37/km pace, with equivalent race times of 5K 20:24, 10K 42:17, half marathon 1:33:40.

What are the Daniels training paces for VDOT 48.7? Easy 5:25/km (E), Marathon 4:45/km (M), Threshold 4:26/km (T), Interval 4:00/km (I), Repetition 3:38/km (R). The zones build from aerobic base to short-rep speed work.

How accurate are predicted race times across distances? Within plus or minus 1 to 3% for trained runners on flat dry courses. Predictions degrade for distances more than 4x outside the input race; a 5K PR predicts the marathon less reliably than a 10K PR predicts the half.