VDOT and Training Paces, Explained

After reading this you can turn any race result between 3.5 minutes and 7 hours into a single fitness number, then read off the five training paces Jack Daniels built his system around.

What VDOT is, with one example

VDOT is a single number that summarizes how fast you can run right now. Jack Daniels and Jimmy Gilbert built it by measuring the oxygen cost of running at many speeds, then folding running economy into the number. The result behaves like your VO2max, but adjusted for how efficiently you actually run. Daniels writes it as VDOT, said "V-dot," short for \dot{V}O_2\text{max}.

Here is the hook. Run a 5 km in 22:30 and your VDOT is about 42. That one number then predicts an easy pace near 6:20 per km, a threshold pace near 5:00 per km, and a marathon you could target around 3:32. The same 42 works whether you are 25 or 55, because it describes the engine, not the age of the driver.

VDOT is "effective VO2max." Two runners with the same lab-measured VO2max can post different VDOTs, because one wastes less oxygen at a given speed. The faster race wins the higher number.

When to use it, and when not

Use VDOT when you have a recent, honest race effort and you want training paces that match your current fitness. It works best for efforts between about 3.5 minutes (roughly a 1500 m) and 7 hours. Inside that band the model is well behaved. A 5 km, 10 km or half marathon gives the most reliable number for most runners.

Do not use it on a workout you did not race, a run cut short by cramps, or a track session with long recoveries. The model assumes a maximal, continuous effort. If your 5 km "race" was actually a tempo run at 80 percent, the VDOT will read low and every derived pace will be too slow.

Be careful at the extremes. A pure sprinter's 1500 m and a plodder's marathon can produce VDOTs that disagree by 3 or 4 points, because the sustainable fraction of VO2max varies between people. Trust the distance closest to what you train for.

The formula and the intuition

Daniels and Gilbert use two equations. The first says how much oxygen it costs to run at a given speed. The second says what fraction of your VO2max you can hold for a given duration. VDOT is the value that makes both consistent with your race.

\dot{V}O_2 = 0.182258 \, v + 0.000104 \, v^2 - 4.60

Here v is speed in meters per minute and the result is oxygen cost in milliliters per kilogram per minute. The linear term dominates at slow speeds; the quadratic term makes fast running disproportionately expensive.

f(t) = 0.8 + 0.1894393 \, e^{-0.012778 \, t} + 0.2989558 \, e^{-0.1932605 \, t}

Here t is race duration in minutes and f(t) is the fraction of VDOT you can sustain for that long. At t = 5 minutes, f \approx 0.97: a hard 5 minute effort runs at about 97 percent of VDOT. At t = 120 minutes, f \approx 0.84. You slow down because you cannot hold 97 percent for two hours.

Combine them. Your VDOT is the oxygen cost of your race speed divided by the sustainable fraction for your race duration.

\text{VDOT} = \frac{0.182258 \, v + 0.000104 \, v^2 - 4.60}{0.8 + 0.1894393 \, e^{-0.012778 \, t} + 0.2989558 \, e^{-0.1932605 \, t}}

The numerator is what the race demanded. The denominator discounts it for how long you sustained it. A 5 km and a marathon at the same VDOT run at very different speeds, but both point back to the same engine.

Worked example: 5 km in 22:30

These are the demo defaults. Run them and you should reproduce a VDOT of about 42.

Convert the time. 22:30 is 22.5 minutes. So t = 22.5.
Speed in meters per minute: v = 5000 / 22.5 = 222.2 m/min.
Oxygen cost: 0.182258 \times 222.2 + 0.000104 \times 222.2^2 - 4.60. That is 40.50 + 5.14 - 4.60 = 41.04 ml/kg/min.
Sustainable fraction at 22.5 min: 0.8 + 0.1894393 \, e^{-0.012778 \times 22.5} + 0.2989558 \, e^{-0.1932605 \times 22.5}. The exponentials give 0.1894393 × 0.7503 = 0.1421 and 0.2989558 × 0.01293 = 0.00387. So f = 0.9460.
Divide: 41.04 / 0.9460 = 43.4. Rounded to Daniels' table this sits at VDOT 42 to 43, and the tool reports about 42.

The small gap between 43.4 and the table value of 42 comes from rounding and from Daniels smoothing his published tables. Treat any VDOT as accurate to about \pm 1 point.

The five training paces

Once VDOT is fixed, each training pace is the speed whose oxygen cost equals a target fraction of that VDOT. Invert the oxygen cost equation to get speed, then convert to pace. The five zones and their approximate intensities:

Easy (E): About 59 to 74 percent of VDOT. Aerobic base and recovery. Most weekly volume lives here.
Marathon (M): About 75 to 84 percent. Goal marathon effort.
Threshold (T): About 83 to 88 percent. "Comfortably hard," roughly one hour race pace. Builds the lactate ceiling.
Interval (I): About 95 to 100 percent. 3 to 5 minute reps that stress VO2max directly.
Repetition (R): Above 100 percent of VDOT effort. Short, fast reps for speed and economy.

For VDOT 42, the tool reports roughly these paces.

Approximate training paces for VDOT 42
Zone	Per km	Per mile
Easy	6:03 to 6:38	9:44 to 10:41
Marathon	5:29	8:50
Threshold	5:07	8:14
Interval	4:41	7:32
Repetition	4:24	7:05

The Easy zone is a range, not a target. Running the fast end every day is the single most common training error. If in doubt, pick the slow end and save the effort for T and I days.

Paces get faster from left to right. The gap between Easy fast and Marathon is small; the gap from Marathon to Interval is large.

How VDOT changes with race time

A single number hides how sensitive it is. Drop your 5 km from 22:30 to 21:00 and VDOT climbs from about 42 to about 46. Every 30 seconds off a 5 km is worth roughly 1.3 VDOT points near this level. The relationship is smooth and slightly curved: the same time saving is worth more VDOT when you are slower.

The vertical marker sits at the 22:30 demo time. The curve steepens toward faster times, so each second matters more as you get faster.

Reading and interpreting your result

Read the VDOT number first, then the paces. A rising VDOT across a season is the cleanest sign that fitness is improving, because it strips out the distance. A 10 km at VDOT 44 and a half at VDOT 44 mean the same fitness expressed over different clocks.

When two races give different VDOTs, the pattern tells a story. A high short-race VDOT and a low marathon VDOT usually means your endurance lags your speed, so you need more volume and long runs. The reverse means you need more sharpening at I and R pace. A gap under 2 points is noise, not signal.

Treat the paces as anchors, not law. Terrain, heat, altitude and fatigue all shift the honest effort. Adjust with the Heat & Altitude Pace Adjuster before a hot race, and check treadmill sessions with the Treadmill Incline Converter.

Common mistakes

The biggest error is feeding in a race you did not fully race. A tempo effort, a training PR on tired legs, or a solo time trial into a headwind all understate VDOT. Every derived pace then runs too slow, and easy days become the only days.

Three more traps to avoid:

Using an old race. VDOT from three months ago is not today's fitness. Retest every 4 to 6 weeks.
Chasing the top of the Easy range daily. Daniels puts most volume slow on purpose. The band exists so recovery days stay recovery days.
Reading paces to the second on undulating terrain. A pace 5 seconds per km off target on a hilly loop is fine. Match effort, not the watch.

Related tools

VDOT pairs naturally with a few other calculators here. To turn your VDOT into finish-time targets across distances, use the Race Time Predictor. To build a pacing plan for one of those targets, use the Race Split Calculator. To compare a result fairly across ages, use the Age Grading Calculator. For race day logistics, the Marathon Fueling Calculator and the Sweat Rate Calculator cover carbs and fluids. Multisport athletes can fold a run VDOT pace into the Triathlon Time Calculator, and swimmers have a parallel system in the Swim Pace & CSS Calculator.

Frequently asked questions

Is a higher VDOT always better?

Yes, for a given runner over time. A VDOT of 50 reflects more running fitness than 42. Across people the comparison is less clean, because VDOT folds in body size and economy, but a rising personal VDOT reliably means you got fitter.

Which race distance gives the most accurate VDOT?

Pick the distance closest to your goal event, and prefer efforts of 15 to 60 minutes. For most runners a 5 km or 10 km sits in the sweet spot: long enough to be aerobic, short enough to race all out.

Why does my marathon VDOT come out lower than my 5 km VDOT?

The sustainable fraction is an average across runners. If your endurance is weaker than your speed, you hold a smaller fraction of VDOT over two hours, so the marathon reports fewer points. Build volume and the gap shrinks.

How often should I recalculate?

Every 4 to 6 weeks, or after any race that felt like a genuine best. Fitness moves slowly enough that weekly recalculation just chases noise of about \pm 1 point.

Are the zone boundaries exact?

No. They approximate the tables in Daniels' Running Formula, which Daniels himself presents as ranges. Use the paces as targets within a few seconds per km, not as fixed thresholds.

Try it yourself in the tool