The 5K Pace Calculator converts your finish time into pace per km, pace per mile, and running speed, then predicts your 10K and half marathon potential using the Riegel formula. Perfect for setting race goals and structuring training zones.
5
min/km
8.05
min/mi
7.46
mph
12
km/h
52.1
min
115
min
8.8
min/mi
5
min/km
8.05
min/mi
7.46
mph
12
km/h
52.1
min
115
min
8.8
min/mi
The calculator for 5K pace planning converts your target finish time into exact per-kilometer and per-mile splits, average running speed, and scientifically projected times at longer distances. The 5K (3.107 miles) is the world's most popular race distance — understanding your pace is the foundation of both race-day execution and structured training.
Runners use pace and speed interchangeably, but they express different things. Pace measures time per unit distance (e.g., 6:00 min/km), while speed measures distance per unit time (e.g., 10 km/h). The conversion between them is:
Speed (km/h) = 60 / Pace (min/km)
GPS watches display pace; treadmills display speed. Knowing both lets you maintain consistent effort across outdoor and indoor training. The 10K pace calculator applies the same conversion for the next most popular race distance.
This calculator uses the Riegel formula to project your performance at longer distances based on your 5K time. The formula accounts for the physiological reality that runners slow proportionally as distance increases:
T2 = T1 × (D2 / D1)1.06
A runner finishing 5K in 25:00 can expect approximately 52:13 for a 10K and 1:55:45 for a half marathon under equivalent conditions. The marathon pace calculator and half marathon pace calculator extend these predictions to longer events.
Understanding where your time fits in the competitive landscape helps set realistic and motivating goals:
The average 5K finish time for all participants globally is approximately 28–32 minutes. Any sub-30-minute 5K places you in the faster half of most recreational fields. The distance running calculators category includes heart rate, training zone, and race improvement tools.
Your 5K pace is a reliable anchor for structuring training intensities. Most coaches define training zones relative to race pace:
Use this online calculator to establish your current 5K pace, then apply these offsets to every session in your training plan. The target heart rate calculator provides the physiological complement to pace-based zone training.
The 5K Pace Calculator computes pace, speed, and race predictions using straightforward division and the Riegel prediction model.
Pace per Kilometer:
$$p_{km} = \frac{T}{5} \quad \text{(seconds per km)}$$
Pace per Mile:
$$p_{mile} = p_{km} \times 1.60934$$
Average Speed:
$$v = \frac{5}{T / 3600} = \frac{18000}{T} \quad \text{(km/h)}$$
Riegel Race Prediction Formula:
$$T_2 = T_1 \times \left(\frac{D_2}{D_1}\right)^{1.06}$$
For 10K prediction: \(D_2/D_1 = 10/5 = 2\), so \(T_{10K} = T_{5K} \times 2^{1.06}\)
For half marathon prediction: \(D_2/D_1 = 21.0975/5 = 4.2195\), so \(T_{HM} = T_{5K} \times 4.2195^{1.06}\)
The exponent 1.06 reflects the empirical observation that running pace decreases by approximately 6% for each doubling of race distance.
Your pace per kilometer and per mile show the steady speed needed to achieve your target 5K time. The average speed in km/h can be used for treadmill settings. The predicted 10K time uses the well-validated Riegel formula and is generally accurate to within 1-2% for trained runners racing on similar courses. The predicted half marathon time is a rougher estimate and assumes equivalent training for the longer distance. Pace values are displayed in MMSS format where 500 means 5 minutes and 0 seconds. For PR attempts, aim for even splits; for competitive racing, consider a slight negative split with a strong finishing kick in the final 400 meters.
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A 25:00 5K at 5:00/km pace predicts approximately 52:09 for 10K and 1:55:11 for half marathon using the Riegel formula.
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A 20:00 5K at 4:00/km pace is competitive at the club level, predicting approximately 41:67 10K and 1:34:09 half marathon.
The Riegel formula (T2 = T1 * (D2/D1)^1.06) was developed by Pete Riegel in 1977 and predicts race times at one distance based on performance at another distance. It is most accurate when predicting between similar distances (5K to 10K) and becomes less reliable for large distance jumps (5K to marathon). The formula assumes equal training and fitness for both distances and is typically accurate to within 2-3% for trained runners.
For men aged 20-29: competitive is under 20 minutes, good is 20-25, average is 25-35. For men 30-39: competitive is under 21, good is 21-27, average is 27-37. For women 20-29: competitive is under 23, good is 23-30, average is 30-40. Times naturally increase with age, and age-graded calculators can compare performances across age groups fairly.
For your first 5K, start conservatively at a pace you can sustain while breathing comfortably. Run the first kilometer slightly slower than your target pace to warm up and avoid oxygen debt. Maintain a steady effort through kilometers 2-4. If you have energy remaining, increase your pace in the final kilometer. Avoid the temptation to sprint the first 400 meters, which almost always leads to a painful slowdown.
5K pace serves as a key reference for interval training. VO2 max intervals (1000m-1200m repeats) should be run at 5K pace or 5-10 seconds per km faster. Speed intervals (400m repeats) should be 15-20 seconds per km faster than 5K pace. Tempo runs should be 15-25 seconds per km slower than 5K pace. Recovery runs should be 60-90 seconds per km slower than 5K pace.
The Riegel formula can estimate marathon time from 5K (T_marathon = T_5K * 8.439^1.06), but the prediction becomes unreliable for such a large distance ratio. Marathon performance depends heavily on factors not tested in a 5K: glycogen management, fueling strategy, heat tolerance, and training volume. A more reliable approach is to race a half marathon first and predict marathon time from that distance.
Road surfaces are fastest due to their firmness and consistency. Track surfaces (synthetic rubber) are approximately 1-2% faster than road due to energy return and precise distance. Trail surfaces vary widely; packed dirt adds 5-10% to 5K time, while technical trails with rocks and roots can add 15-30%. Cross-country grass surfaces typically add 5-15% to road 5K times depending on terrain and conditions.
Multiply your pace per kilometer by 1.60934 to get pace per mile. For example, a 5:30 min/km pace equals 5:30 × 1.60934 = 8:51 min/mile. Alternatively, divide 60 by your speed in km/h to get min/km, then multiply by 1.60934 for min/mile. Most GPS watches display both units simultaneously — simply toggle the display setting to switch between metric and imperial pace readouts.
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