Running Pace & Race Time Calculator | Plan & Predict

Q: What if my recent race was hilly?

Use the 'Elevation Gain' input (in optional settings). Hills increase effort, so your 'flat equivalent' pace is actually faster than your raw time suggests.

Calculate pace, predict race times, and get personalized training zones based on your performance.

What do you want to calculate?

Calculate Pace Calculate Time Calculate Distance Race Predictor Training Paces

Distance

Enter the distance ran or planned.

Time (Duration)

Hrs

Mins

Secs

Your Pace

--:--

per km

Time

Distance

Speed

Calories

Predicted Race Times Riegel Formula

Distance	Predicted Time	Pace

Training Zones Estimated Zones

Zone	Pace (min/km)	Description

How to Use This Running Calculator

Choose Calculation

Select "Pace" to find your speed, or "Race Predictor" to see potential times for new distances.

Enter Data

Input your recent time and distance. For Training Paces, use a recent race result.

Get Insights

View your pacing, speed conversions, and split times instantly.

Refine (Optional)

Add body weight to see calorie burn estimates or elevation to adjust for hills.

Running Pacing Strategies

Applying your calculator results to race day requires strategy. Here are the most common approaches:

Negative Split: Start slightly slower than your goal pace for the first half, then accelerate. This is the gold standard for personal bests.
Even Split: Maintain a consistent pace from start to finish. Best for flat courses like track races or flat marathons.
Positive Split: Banking time early by running fast, accepting you will slow down. Often risky and painful in the final kilometers.

Understanding Your Training Paces

Easy Runs

60-70% effort. Builds aerobic base and aids recovery. You should be able to hold a full conversation.

Threshold

80-90% effort. "Comfortably hard." Improves your body's ability to clear lactate.

Intervals

95-100% effort. Builds VO2 max. Hard efforts lasting 3-5 minutes with rest in between.

Repetitions

Sprint pace. Improves running economy and speed. Short bouts (200-600m) with full recovery.

How Accurate Are Race Predictions?

What formula is used?

We use Riegel's Formula (1977), which is the industry standard: T2 = T1 × (D2 / D1)^1.06. It assumes you have trained appropriately for the specific distance you are predicting.

When are predictions less accurate?

Predictions lose accuracy when the target distance is more than 3-4x the input distance (e.g., predicting a marathon from a 5K time). Ultra distances (50km+) also introduce fatigue factors the formula cannot model perfectly.

Note on Calorie Estimates: Calorie values are based on MET (Metabolic Equivalent) standards for running speeds. Actual burn varies based on individual metabolism, terrain, wind resistance, and running efficiency. Treat these numbers as a baseline estimate rather than an exact scientific measurement.

Common Running Calculator Mistakes

Ignoring Training Volume: A fast 5K time predicts a fast marathon, but only if you've done the long runs to support it.
Overlooking Terrain: Hills slow you down. If your input race was downhill, your prediction for a flat course will be too fast.
Training Too Fast: Many runners do their "easy" runs at "threshold" pace. Use the calculator to slow down your easy runs for better recovery.

Frequently Asked Questions

Why is my predicted race time different from my goal?

The calculator relies on past performance data. If your prediction is slower than your goal, it means you need to improve your fitness (VDOT) through structured training before you can realistically hit that goal.

Can I use this for walking?

Yes, the math works for any speed. However, walking mechanics are different, so calorie burn estimates may be slightly less accurate compared to running MET values.

What if my recent race was hilly?

Use the "Elevation Gain" input (in optional settings). Hills increase effort, so your "flat equivalent" pace is actually faster than your raw time suggests.