Training Pace Calculator (VDOT Zones)

What does this calculator do?

The training pace calculator turns a recent race into a set of training intensities. From the same VDOT used in race prediction it derives five pace zones — Easy / Long, Marathon, Threshold, Interval and Repetition — each as a mid-pace plus a range. If you add age and resting heart rate, it also shows five Karvonen heart-rate zones (Tanaka estimate of max HR).

Typical uses: setting easy-run pace so recovery days stay easy, choosing a tempo / threshold pace, and checking that interval 400s are not accidentally a repetition session. It is a training-intensity map, not a weekly plan; the training plan generator is a separate tool.

How does it work?

First the known race is converted to VDOT with the Daniels–Gilbert oxygen-cost equations (the same VDOT as the race time predictor). Each zone is a published fraction of that VDOT. Endurometry then converts the fraction back to a running pace with the inverse oxygen-cost curve: faster fractions of VDOT mean a higher oxygen cost and therefore a faster pace.

The number in the middle of each row is the midpoint of that zone; the range is the slower and faster ends. Heart-rate zones, when shown, are independent of VDOT: they use heart-rate reserve (Karvonen) from your resting HR and a Tanaka max HR (208 − 0.7 × age). They are a second language for intensity, not a rewrite of the pace table.

Formula

VDOT from a race: same Oxygen Power (1979) equations as race prediction

pace at fraction p:
  v (m/min) = velocityFromVo2(VDOT × p)
  pace      = 1000 / v × 60   // seconds per km

Endurometry zone fractions of VDOT
  Easy / Long     59–74%
  Marathon        75–84%
  Threshold       83–88%
  Interval        95–100%
  Repetition      105–120%

Optional HR (Karvonen)
  HRmax ≈ 208 − 0.7 × age     // Tanaka 2001
  HR    = (HRmax − HRrest) × % + HRrest

Paces are computed from the equations, not looked up in the printed VDOT tables in Daniels’ Running Formula. Small differences from the book tables are expected (rounding and table interpolation). Marathon and Threshold ranges overlap slightly; that overlap is in the published intensity bands.

Worked example

How to interpret the result

Easy should feel easy. If your “easy” runs sit at the fast end of Marathon pace, you are not using the zone as intended — most recreational runners err that way. Threshold is quality work, not an everyday pace; Interval is VO2max reps with recovery; Repetition is faster still, usually short and with full recovery.

Use the pace zones to write sessions, and the heart-rate zones as a cross-check on easy days (heat, hills and fatigue raise HR at the same pace). For a fuller HR calculator, including a measured max HR, use the heart-rate zone calculator. How the intensities fit a week is in the easy / tempo / long-run guide.

Assumptions and limitations

Assumptions

• The known result is a genuine race effort, used to estimate current endurance fitness (VDOT).
• Zone fractions are Daniels-style % of VDOT; paces are taken from the oxygen-cost curve, not from a printed lookup table.
• Heart-rate zones, when shown, assume the Tanaka age formula unless you later enter a measured max HR on the dedicated HR page.

Limitations

• VDOT is an endurance index from a race, not a laboratory VO2max. Two runners with the same 10K can need different easy paces on the trail or in the heat.
• Paces will not match Daniels’ printed tables to the second. This page solves the published equations; the book tables are rounded and interpolated.
• Easy pace is a range, not a single number. Starting at the slower end is the usual advice until you know how you recover.
• Heart-rate zones here cannot use a measured max HR — only Tanaka from age. Resting HR ≥ max HR is ignored rather than displayed.
• The calculator does not prescribe weekly volume, recovery or which mix of zones you need. That is coaching, not arithmetic.
• Inputs faster than 1:00/km or slower than 2:00:00/km, or a VDOT outside 10–90, are rejected as almost certainly a bad race time.

Methodology and sources

Method type: Published model

Training paces implement Daniels–Gilbert (1979) oxygen-cost equations plus Daniels’ published intensity fractions of VDOT. Optional heart-rate zones use Tanaka (2001) for max HR and Karvonen (1957) heart-rate reserve. Paces are solved from the equations, not copied from official VDOT tables.

• Methodology: Training paces (VDOT zones)
• Methodology: Rounding and displayed precision

Sources: Daniels–Gilbert 1979 · Daniels’ Running Formula · Karvonen 1957 · Tanaka 2001

Last reviewed: October 5, 2026