Pace Calculator

INTRODUCTION

You finished your first 5K.

The clock read 28 minutes 30 seconds.

You felt proud. You felt exhausted. You felt confused.

"Is that good?" you asked.

Your friend ran it in 22 minutes. She seemed disappointed.

Your coworker ran it in 35 minutes. He was ecstatic.

You had no context. No benchmark. No idea what your time meant.

So you signed up for a 10K. You trained for 8 weeks. You ran it in 58 minutes.

You thought: "I doubled the distance. My time should double too. 57 minutes would be right."

But 5K pace and 10K pace are not the same. No one runs a marathon at their 5K pace.

A 28:30 5K predicts a 59:30 10K. You were right on track. But you did not know that.

You felt slow. You felt discouraged. You almost quit.

Then you discovered pace.

Pace is not time. Pace is speed per unit of distance. Minutes per mile. Minutes per kilometer.

It is the universal language of running.

A 9:10/mile pace is a 28:30 5K.

A 9:10/mile pace is a 57:00 10K.

A 9:10/mile pace is a 2:00:00 half marathon.

A 9:10/mile pace is a 4:00:00 marathon.

Same pace. Different distances. Different times.

But here is what pace also reveals:

Your 5K PR is 8:00/mile. Your marathon goal is 8:00/mile.

That is not a goal. That is a fantasy.

No one holds 5K pace for 26.2 miles. The body does not work that way.

A 20:00 5K (6:26/mile) predicts a 3:15 marathon (7:27/mile). Not 6:26. Not even close.

The Pace Calculator shows you these relationships. It predicts race times from other race times. It calculates split times for interval training. It converts between miles and kilometers. It shows you what is realistic and what is delusion.

In 2026, with Strava, Garmin, and Apple Watch tracking every step but rarely explaining what the numbers mean, understanding pace is not optional.

It is essential for every runner, from first 5K to Boston Qualifier.

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WHAT IS A PACE CALCULATOR?

A pace calculator is a tool that converts between time, distance, and pace — the three pillars of running performance.

It handles every calculation a runner needs:

• Pace from Time and Distance — "I ran 5 miles in 42 minutes. What was my pace?"

• Time from Pace and Distance — "I want to run a 4-hour marathon. What pace do I need?"

• Distance from Pace and Time — "I held 8:00/mile for 45 minutes. How far did I run?"

• Race Prediction — "My 10K PR is 50:00. What marathon time can I expect?"

• Split Times — "I need 7:30/mile for a 3:17 marathon. What are my 5K splits?"

• Interval Pacing — "My 5K pace is 6:30. What should my 400m repeats be?"

• Pace Conversion — Miles to kilometers, minutes per mile to miles per hour.

Standard inputs:

• Distance (miles or km, or race type: 5K, 10K, half, marathon)

• Time (hours, minutes, seconds)

• Pace (per mile or per km)

• Known race result (for prediction)

• Target race (for goal setting)

Outputs you get:

• Pace in min/mile and min/km

• Speed in mph and km/h

• Projected times for other distances

• Split times at every mile or kilometer

• Negative split strategy (even pacing vs. fade analysis)

• Training paces (easy, tempo, threshold, interval, repetition)

• VO2 max estimate (from race performance)

It answers the questions every runner asks:

"How fast was I actually running?"

"What pace do I need for my goal time?"

"If I can run a 25-minute 5K, what is my marathon potential?"

"How should I pace my race to avoid bonking?"

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HOW TO USE THE NUMOVIX PACE CALCULATOR

Our calculator gives you instant, accurate pace data in under 30 seconds.

Step 1:

Select your calculation type.

Example: "Find pace from time and distance"

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Step 2:

Enter your distance.

Example: 5 miles

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Step 3:

Enter your time.

Example: 42 minutes 30 seconds

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Step 4:

Click "Calculate."

You will instantly see:

Example: 5 miles in 42:30

• Pace: 8:30 per mile

• Pace (metric): 5:17 per km

• Speed: 7.06 mph

• Speed (metric): 11.36 km/h

• Estimated VO2 max: 42.3 ml/kg/min

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Example: "Find time from pace and distance"

Goal: Sub-4-hour marathon

Needed pace: 9:09 per mile

Calculator shows:

• Marathon time at 9:09/mile: 3:59:58

• 5K split: 28:24

• 10K split: 56:48

• Half split: 1:59:59

• 20-mile split: 3:03:00

• Final 10K: 57:00 (even pace strategy)

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Example: "Race prediction from known result"

Known: 10K in 50:00 (8:03/mile)

Predicted times:

• 5K: 23:45 (7:39/mile)

• Half marathon: 1:50:30 (8:26/mile)

• Marathon: 3:50:00 (8:47/mile)

Note: Marathon prediction assumes proper training and pacing. A 50:00 10K does not guarantee a 3:50 marathon without mileage base.

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THE MATH BEHIND PACE CALCULATION

Understanding the formulas helps you calculate anywhere and verify your training targets.

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Pace from Time and Distance:

Pace (min/mile) = Total Minutes ÷ Distance in Miles

Example:

42.5 minutes ÷ 5 miles = 8.5 minutes/mile = 8:30/mile

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Time from Pace and Distance:

Total Minutes = Pace (decimal) × Distance

Example:

8.5 min/mile × 26.2 miles = 222.7 minutes = 3:42:42

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Speed from Pace:

mph = 60 ÷ Pace (decimal minutes)

Example:

60 ÷ 8.5 = 7.06 mph

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Metric Conversions:

min/km = min/mile × 0.6214

Example:

8:30/mile × 0.6214 = 5:17/km

km/h = mph × 1.609

Example:

7.06 mph × 1.609 = 11.36 km/h

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Race Prediction Formulas (Riegel's Formula):

T2 = T1 × (D2 ÷ D1)^1.06

Where:

• T1 = known time

• D1 = known distance

• D2 = target distance

• 1.06 = fatigue factor (pace slows with distance)

Example:

Known: 10K in 50:00. Predict half marathon (13.1 miles = 21.1 km).

T2 = 50 × (21.1 ÷ 10)^1.06

T2 = 50 × 2.11^1.06

T2 = 50 × 2.21

T2 = 110.5 minutes = 1:50:30

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Cameron's Formula (Alternative for Shorter Distances):

More accurate for 5K to 10K predictions.

T2 = T1 × (D2 ÷ D1)^1.08

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VO2 Max Estimate (Daniels' Running Formula):

VO2 max = (−4.60 + 0.182258 × S + 0.000104 × S²) ÷ (0.8 + 0.1894393 × e^(−0.012778 × T) + 0.2989558 × e^(−0.1932605 × T))

Where:

• S = speed in meters/minute

• T = time in minutes

• e = Euler's number

Example: 5K in 25:00

Speed: 5000m ÷ 25min = 200 m/min

VO2 max ≈ 45 ml/kg/min (good recreational runner)

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Complete Real Example:

Aisha's Marathon Journey:

Starting Point:

• Age: 34

• Ran first 5K: 28:30 (9:10/mile)

• Goal: Boston Marathon qualifying time (3:30 for women 35–39)

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Month 1: Understanding Pace

Aisha uses the calculator.

Current 5K: 28:30 = 9:10/mile

Predicted marathon from 5K: 4:15:00 (9:45/mile)

She needs 3:30:00 (8:00/mile).

Gap: 1:15 per mile faster. Significant.

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Month 6: First 10K

Aisha trains consistently. Runs 10K in 54:00 (8:41/mile).

Calculator predictions from 10K:

• Half marathon: 1:59:00 (9:05/mile)

• Marathon: 4:05:00 (9:21/mile)

Still 35 minutes from Boston. But improving.

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Month 12: Half Marathon

Aisha runs half marathon: 1:52:00 (8:33/mile).

Calculator predictions:

• Marathon: 3:52:00 (8:51/mile)

• Needed for Boston: 3:30:00 (8:00/mile)

Gap: 51 seconds per mile. Tough but possible with focused training.

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Month 18: Final Tune-Up

Aisha runs 10K time trial: 46:00 (7:25/mile).

Calculator predictions:

• Half marathon: 1:41:00 (7:44/mile)

• Marathon: 3:28:00 (7:57/mile)

Under Boston qualifying pace.

She registers for Boston-qualifying race. Uses calculator to plan:

• Goal: 3:29:00 (7:59/mile)

• First half: 1:44:30 (7:59/mile)

• Second half: 1:44:30 (negative split strategy)

• 5K splits: 24:48 each

Race day: She executes. Finishes 3:28:47.

Calculator was accurate within 13 seconds.

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TRAINING PACES FROM RACE PACE

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Example: Marathon Goal 8:00/mile

| Training Type | Target Pace |

| Recovery | 9:30–10:30/mile |

| Easy | 9:00–9:30/mile |

| Long Run | 8:30–9:00/mile |

| Marathon Pace | 8:00/mile |

| Tempo | 7:30–7:45/mile |

| 10K Pace | 7:15–7:30/mile |

| 5K Pace | 6:50–7:10/mile |

| Interval | 6:30–6:50/mile |

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WHY EVERY RUNNER NEEDS A PACE CALCULATOR

1. Set Realistic Goals

"I want to run a 3-hour marathon."

Your 5K is 25:00. Calculator predicts 3:50 marathon.

A 3-hour marathon requires a 20:00 5K. You are not close.

Set intermediate goals. Build progressively.

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2. Avoid Race Day Disasters

You run 8:00/mile for the first half of a marathon.

Your 5K PR pace is 7:30. You think: "I am being conservative."

But 8:00 is your threshold pace. Not your marathon pace.

You bonk at mile 20. Walk the last 10K.

Calculator would have shown: Your marathon pace from 5K PR is 8:45.

You went out 45 seconds per mile too fast.

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3. Structure Interval Workouts

"Run 400m repeats at 5K pace."

Your 5K is 22:00 (7:05/mile).

400m = 0.248 miles.

Target: 7:05/mile × 0.248 = 1:46 per 400m.

Calculator gives you exact split targets. No guessing.

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4. Convert Between Miles and Kilometers

European race: 10K. Your training is in miles.

10K = 6.2 miles. Goal: 50:00 = 8:03/mile = 5:00/km.

Calculator converts instantly.

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5. Track Progress Objectively

January: 5K in 28:00 (9:01/mile).

June: 5K in 25:30 (8:12/mile).

Pace improved by 49 seconds per mile.

Not just "faster." Precisely, measurably faster.

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KEY FACTORS THAT AFFECT PACE

Distance:

No one holds 5K pace for a marathon.

| 20:00 (6:26/m) | 41:40 (6:43/m) | 1:32:00 (7:02/m) | 3:15:00 (7:27/m) |

| 25:00 (8:03/m) | 52:00 (8:22/m) | 1:55:00 (8:47/m) | 4:03:00 (9:17/m) |

| 30:00 (9:40/m) | 1:02:30 (10:03/m) | 2:18:00 (10:33/m) | 4:52:00 (11:09/m) |

Note how pace slows significantly with distance.

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Training Volume:

A 20:00 5K predicts 3:15 marathon.

But only if you run 40–60 miles per week. With long runs of 18–22 miles.

Without the mileage base, the prediction is fantasy.

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Course and Conditions:

Hilly course: Add 10–30 seconds per mile.

Hot weather (70°F+): Add 15–45 seconds per mile.

Humidity: Slows sweat evaporation, raises heart rate.

Altitude: Reduces oxygen, slows pace 5–15%.

Calculator assumes flat, cool, sea-level conditions. Adjust expectations.

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Age:

VO2 max declines ~1% per year after 30.

A 40-year-old with the same training as a 30-year-old will be 10% slower.

Age-graded calculators adjust for this. Use them for fair comparison.

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Gender:

Women typically have lower VO2 max but better fat oxidation.

At equal VO2 max, women may outperform men in ultras.

Pace predictions are gender-neutral. Age-grading adjusts for sex.

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COMMON MISTAKES RUNNERS MAKE

Mistake 1: Running Every Run Too Fast

Easy runs at marathon pace. Tempo runs at 5K pace.

Result: Chronic fatigue. No adaptation. Stagnation or injury.

Calculator shows: Easy should be 90 seconds slower than marathon pace.

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Mistake 2: Starting Races Too Fast

First mile: 30 seconds faster than goal pace.

Feels easy. Feels smart.

Mile 20: Walking. Missing goal by 20 minutes.

Use calculator splits. Stick to them. Negative split if possible.

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Mistake 3: Ignoring the Fatigue Factor

"I ran 8:00/mile for 10K. I will run 8:00 for half marathon."

No. Riegel's formula: 8:00 10K = 8:26 half marathon pace.

The body slows. Accept it. Plan for it.

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Mistake 4: Comparing Apples to Oranges

Your hilly 5K in 26:00 vs your friend's flat 5K in 24:00.

Your effort may have been equivalent. Calculator cannot see hills.

Use effort-based metrics (heart rate, RPE) alongside pace.

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Mistake 5: Not Updating Predictions as Fitness Changes

January 5K: 30:00. Calculator predicts 4:30 marathon.

You train hard. June 5K: 25:00. Still using January prediction?

Recalculate. Your potential changed.

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Mistake 6: Racing Without Pace Awareness

No watch. No splits. Just "run by feel."

Elite runners can do this. You cannot.

First-time marathoners without pace plans finish 20–40 minutes slower than predicted.

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Mistake 7: Obsessing Over Exact Pace

Target: 8:00/mile. You run 8:05. Panic.

±5 seconds per mile is fine. Wind, hills, hydration stations vary.

Aim for average pace, not perfect splits.

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PRO TIPS TO MASTER YOUR PACE

Tip 1: Learn Your Easy Pace by Heart Rate

Easy runs: 65–75% max heart rate.

If calculator says 9:30/mile easy, but your HR is 165 (Zone 4), slow down.

Pace is a guide. Physiology is truth.

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Tip 2: Practice Goal Pace in Training

Marathon goal: 8:00/mile.

Run 6–10 miles at 8:00/mile every other week.

Teach your body what it feels like. Memorize the rhythm.

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Tip 3: Use the Calculator for Treadmill Workouts

Treadmill shows mph. You think in min/mile.

Calculator: 7.5 mph = 8:00/mile.

Set the treadmill. Know your pace.

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Tip 4: Plan Negative Splits

First half: 1–2 seconds slower than goal pace per mile.

Second half: 1–2 seconds faster.

Feels conservative. Finishes strong. Beats goal.

Elite records are almost all negative splits.

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Tip 5: Recalculate After Every Race

New 5K PR? New half marathon?

Enter it. Update predictions. Adjust training paces.

Fitness changes. Your numbers should too.

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Tip 6: Use Age-Graded Percentages

40-year-old running 20:00 5K = 70.2% age-graded.

25-year-old running 18:00 5K = 70.5% age-graded.

Nearly equivalent performances. Fair comparison across ages.

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Tip 7: Account for Course in Goal Setting

Boston Marathon: Net downhill first half, uphill Newton hills 16–21.

Goal pace: 7:00/mile flat. Adjust to 6:50 first half, 7:10 second half.

Calculator gives flat predictions. You apply course knowledge.

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QUICK SUMMARY

Before you use the calculator, remember these key points:

• Pace = time ÷ distance — the universal language of running

• Race predictions use Riegel's formula with a 1.06 fatigue factor

• No one holds 5K pace for a marathon — pace slows 10–25% with distance

• Training paces are derived from race pace at 65–110% intensity

• Easy runs should feel easy — 60–90 seconds slower than marathon pace

• Start races conservatively — negative splits beat positive splits

• Recalculate after every PR — your potential changes with fitness

• Course and conditions matter — hills, heat, humidity slow you down

• Age-graded percentages allow fair comparison across ages and genders

• Mileage base matters — predictions assume adequate training volume

• Pace is a guide, not a prison — adjust for feel, heart rate, and conditions

• The calculator turns guessing into planning — use it for every race and workout

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FREQUENTLY ASKED QUESTIONS

Q1: How do I calculate my running pace?

Pace (min/mile) = Total Time in Minutes ÷ Distance in Miles

Example: 45 minutes ÷ 5 miles = 9 min/mile.

Pace (min/km) = Total Time in Minutes ÷ Distance in Kilometers

Example: 45 minutes ÷ 8 km = 5:37/km.

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Q2: How can I predict my marathon time from my 5K?

Use Riegel's formula: T2 = T1 × (D2 ÷ D1)^1.06

Example: 5K in 25:00. Predict marathon (26.2 miles = 42.2 km).

T2 = 25 × (42.2 ÷ 5)^1.06

T2 = 25 × 8.44^1.06

T2 = 25 × 9.73

T2 = 243 minutes = 4:03:00

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Q3: What pace should I run for my goal marathon time?

Pace = Goal Time in Minutes ÷ 26.2

Example: 4:00:00 marathon = 240 minutes ÷ 26.2 = 9:10/mile.

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Q4: Why is my marathon slower than predicted?

Common reasons:

• Insufficient weekly mileage

• No long runs over 18 miles

• Started too fast, positive split

• Inadequate fueling/hydration

• Heat, hills, or poor sleep

• Overtraining or injury

Predictions assume proper preparation.

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Q5: What is a negative split?

Running the second half faster than the first.

Example: Half splits of 2:02:00 / 1:58:00 = negative split.

Associated with:

• Better pacing discipline

• Less glycogen depletion

• Faster finish times

• Lower injury risk

Elite performances are predominantly negative splits.

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Q6: How do I convert between min/mile and min/km?

min/km = min/mile × 0.6214

min/mile = min/km × 1.609

Example: 8:00/mile × 0.6214 = 4:58/km.

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Q7: What is age-graded running?

Adjusts performance for age and gender.

A 50-year-old running 20:00 5K = 75% age-graded.

A 30-year-old running 18:00 5K = 75% age-graded.

Equivalent performances. Fair comparison.

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RELATED CALCULATORS

Explore our full suite of free running and fitness tools:

• Heart Rate Zone Calculator

• VO2 Max Calculator

• Race Time Predictor

• Training Pace Calculator

• Split Time Calculator

• Age-Graded Calculator

• Calorie Burn Calculator

• BMI Calculator

• Marathon Pace Chart

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FINAL THOUGHTS

Running is the simplest sport.

Put one foot in front of the other. Repeat.

But simplicity hides complexity.

A 4-hour marathon is not "twice as hard" as a 2-hour half marathon. It is exponentially harder.

A 7:00 mile is not "a little faster" than an 8:00 mile. It is a different energy system, a different lactate threshold, a different level of fitness.

The Pace Calculator reveals these relationships.

It turns "I want to run faster" into "I need to run my tempo runs at 7:30, my intervals at 6:45, and my easy runs at 9:15."

It turns "I want to qualify for Boston" into "I need a 46:00 10K first, then 8:00 marathon pace, then 18-mile long runs."

It turns confusion into clarity. Guessing into planning. Hope into strategy.

Before your next run, calculate your paces.

Before your next race, calculate your splits.

Before your next goal, calculate what it truly requires.

That is how you run smarter.

That is how you run faster.

That is how you cross the finish line exactly when you planned.

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DISCLAIMER

This article is for educational and informational purposes only.

Pace calculations, race predictions, and training paces are estimates based on mathematical formulas and population averages.

The examples provided are illustrative and based on standard running science (Riegel, Daniels, Cameron formulas).

Actual race performance depends on:

• Weekly training mileage and long run distance

• Course profile (hills, altitude, weather)

• Pacing strategy and race execution

• Fueling, hydration, and electrolyte balance

• Sleep, stress, and recovery status

• Genetics and running economy

Always consult a qualified running coach, exercise physiologist, or healthcare provider before beginning intense training programs, especially if you have cardiovascular conditions, are over 40, or are new to running.

Numovix does not provide medical advice, diagnosis, or training prescriptions.

Our calculator results are estimates and should not replace personalized coaching or medical clearance.

If you experience chest pain, dizziness, or unusual fatigue during running, stop immediately and seek medical attention.

Pace Calculator | Calculate Running Pace, Split Times & Race Predictions | Numovix

Free pace calculator. Calculate your running pace, split times, and race predictions for 5K, 10K, half marathon, and marathon. Plan your training, track progress, and hit your goal time. No signup needed.