What is VDOT and where does it come from?

VDOT is Jack Daniels' index of running fitness, expressed in the same units as VO₂max (mL·kg⁻¹·min⁻¹) but derived from race performance rather than laboratory measurement. A separate race-time calculator applies the Daniels-Gilbert oxygen-cost and intensity-fraction equations to invert race distance and time into a VDOT score, which this tool then uses to generate training paces.

Why does this calculator not ask for my recent race time?

This tool requires a pre-computed VDOT as its input. To obtain VDOT from a race result, runners typically use a Daniels VDOT table or a dedicated race-time converter (such as the Run SMART Project calculator) that accounts for the non-linear relationship between race distance, time, and oxygen demand. Once VDOT is known, this tool provides the corresponding training-pace zones.

Why is Repetition (R) pace not included?

Daniels defines Repetition pace as an interval-duration-dependent intensity rather than a fixed percentage of vVDOT. Because R pace varies with the length of each repeat (200 m vs. 400 m, for example), it cannot be expressed as a single pace per kilometre without additional inputs specifying interval distance and rest period.

What does each training zone target?

Easy pace (70% of vVDOT) develops aerobic enzymes and capillary density with minimal fatigue. Marathon pace (80%) trains lactate clearance and fuel efficiency at race effort. Threshold pace (88%) targets lactate steady-state and anaerobic threshold adaptation. Interval pace (98%) stresses VO₂max and running economy at near-maximal aerobic intensity.

Can I use these paces if my VDOT was calculated months ago?

VDOT reflects fitness at the time of the input race performance. Training adaptations or detraining over subsequent weeks or months can shift actual fitness away from the recorded VDOT. Re-testing with a recent race effort or time trial under similar conditions provides a more current VDOT and more accurate training paces.

Running

Training Pace Calculator (from VDOT)

Calculate Easy, Marathon, Threshold, and Interval paces from your VDOT score using Daniels' formula.

Last updated: 22 April 2026

What this tool does

This calculator computes running training paces across four intensity zones—Easy, Marathon, Threshold, and Interval—using Jack Daniels' Running Formula and the Daniels-Gilbert oxygen-cost equation. It takes a single input, the runner's VDOT score, solves the quadratic velocity equation at that VO₂max-equivalent level, then applies zone-specific percentages (70%, 80%, 88%, and 98% of maximum aerobic velocity) to output target paces in minutes per kilometre. The paces are population-average estimates derived from the published Daniels formula and are most applicable to trained distance runners performing steady-state aerobic work.

Inputs

Result

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Formula Used

v_{V D O T} = solve (0.000104 v^{2} + 0.182258 v - 4.6 = VDOT), p_{z o n e} = \frac{60000}{v _{V D O T} \times pct _{z o n e}} sec/km, pct \in {0.70, 0.80, 0.88, 0.98}

VDOT

VDOT score

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How Training Pace Calculator (from VDOT) works

This calculator accepts a VDOT value—Jack Daniels' measure of running fitness—and computes four training pace zones: Easy (E), Marathon (M), Threshold (T), and Interval (I). The tool first solves the Daniels-Gilbert oxygen-cost equation VO₂ = 0.000104·v² + 0.182258·v − 4.6 for v, the velocity in metres per minute that corresponds to the runner's VDOT. Each training zone is then expressed as a percentage of that velocity (Easy = 70%, Marathon = 80%, Threshold = 88%, Interval = 98%) and converted to minutes per kilometre. Repetition pace (R) is omitted because it depends on interval duration rather than a fixed percentage of vVDOT.

The formula

The engine solves the quadratic equation 0.000104·v² + 0.182258·v − (4.6 + VDOT) = 0 for v using the quadratic formula, then calculates seconds per kilometre as 60,000 / (v × percentage) for each zone. The percentages derive from Daniels' extensive treadmill and track research linking relative intensity to physiological outcomes. For example, Threshold pace at 88% of vVDOT targets lactate steady-state, while Easy pace at 70% emphasises aerobic development with minimal fatigue.

Where this method is most accurate

Daniels' VDOT system was developed on competitive distance runners with consistent training backgrounds. The quadratic oxygen-cost model fits well across typical race paces (roughly 10 km to marathon) but is less precise for sprint distances or ultra-marathon efforts where metabolic pathways and fatigue differ. VDOT itself assumes a recent race performance under good conditions; staleness, heat, or altitude can decouple fitness from the input VDOT. The percentage-based zones reflect population averages and may require individual adjustment based on muscle-fibre profile, training history, and recovery capacity.

What this tool does not do

This calculator does not derive VDOT from a race time—users must obtain their VDOT from a separate race-time calculator that applies the full Daniels-Gilbert model. It does not prescribe workout structure, weekly mileage, or progression plans. The paces are estimates; individual lactate profiles, running economy, and environmental conditions can shift optimal training intensities. This tool does not provide medical clearance for training or account for injury history.

Disclaimer

This calculator is an educational tool that applies published formulas to user-supplied data. It does not constitute training advice, medical guidance, or performance guarantees. Numbers produced here are estimates based on population-derived models and may not reflect individual physiology. Consult a qualified coach or healthcare provider before beginning or modifying any training programme.

Questions

What is VDOT and where does it come from?: VDOT is Jack Daniels' index of running fitness, expressed in the same units as VO₂max (mL·kg⁻¹·min⁻¹) but derived from race performance rather than laboratory measurement. A separate race-time calculator applies the Daniels-Gilbert oxygen-cost and intensity-fraction equations to invert race distance and time into a VDOT score, which this tool then uses to generate training paces.
Why does this calculator not ask for my recent race time?: This tool requires a pre-computed VDOT as its input. To obtain VDOT from a race result, runners typically use a Daniels VDOT table or a dedicated race-time converter (such as the Run SMART Project calculator) that accounts for the non-linear relationship between race distance, time, and oxygen demand. Once VDOT is known, this tool provides the corresponding training-pace zones.
Why is Repetition (R) pace not included?: Daniels defines Repetition pace as an interval-duration-dependent intensity rather than a fixed percentage of vVDOT. Because R pace varies with the length of each repeat (200 m vs. 400 m, for example), it cannot be expressed as a single pace per kilometre without additional inputs specifying interval distance and rest period.
What does each training zone target?: Easy pace (70% of vVDOT) develops aerobic enzymes and capillary density with minimal fatigue. Marathon pace (80%) trains lactate clearance and fuel efficiency at race effort. Threshold pace (88%) targets lactate steady-state and anaerobic threshold adaptation. Interval pace (98%) stresses VO₂max and running economy at near-maximal aerobic intensity.
Can I use these paces if my VDOT was calculated months ago?: VDOT reflects fitness at the time of the input race performance. Training adaptations or detraining over subsequent weeks or months can shift actual fitness away from the recorded VDOT. Re-testing with a recent race effort or time trial under similar conditions provides a more current VDOT and more accurate training paces.

Sources & Methodology

Jack Daniels' Running Formula (3rd ed., 2014). Solves the Daniels-Gilbert oxygen-cost equation VO₂ = 0.000104·v² + 0.182258·v − 4.6 for velocity at the runner's VDOT, then applies zone percentages: Easy 70%, Marathon 80%, Threshold 88%, Interval 98%. Output in min/km.

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