Comrades Marathon Pace Calculator: Plan Your Cutoff

The Comrades Marathon pace calculator works out the average pace you need to hold to finish the 87–90 km ultramarathon within the official cutoff time, based on the distance you enter and your target finish time. You input the race distance (in km) and your desired finish time (in hours and minutes), and it returns your required average pace in min/km and your average speed in km/h. This lets you plan training paces, check whether a target time is realistic, and see how much buffer you have against the cutoff.

Formula

The calculator uses the basic relationship between distance, time, and pace:

• Average pace (min/km) = Finish time (minutes) ÷ Distance (km)
• Average speed (km/h) = Distance (km) ÷ (Finish time (minutes) ÷ 60)

Where:

• t = finish time in minutes (e.g., 570 minutes for 9:30:00)
• d = race distance in kilometres (standard Comrades is ~87–90 km, but the exact distance varies slightly year to year)

For example, if you run 90 km in 11 hours (660 minutes), your pace is 660 ÷ 90 = 7.33 min/km, and your speed is 90 ÷ (660/60) = 8.18 km/h.

Worked Example

Using the default values from the calculator above: finish time = 50 minutes, distance = 10 km.

1. Convert finish time to minutes: 50 minutes (already in minutes).
2. Calculate pace: 50 ÷ 10 = 5.00 min/km.
3. Calculate speed: 10 ÷ (50/60) = 10 ÷ 0.8333 = 12.00 km/h.

The calculator shows an average pace of 5.00 min/km and an average speed of 12.00 km/h. That is a brisk but sustainable pace for a 10 km run, but for a Comrades distance you would need to slow down dramatically.

Why the Comrades Distance Matters

The Comrades Marathon is run between Durban and Pietermaritzburg in South Africa, alternating direction each year. The official distance is approximately 87–90 km, but it is not exactly the same every year. The course is measured carefully before each race, and the exact distance is published in the race manual. Because the cutoff is fixed (currently 12 hours for the full race), a one-kilometre difference in course length changes your required pace by roughly 40 seconds per kilometre. Always use the official distance for the year you are running, not a rounded figure.

The race also has significant elevation gain and loss—around 1,000–1,800 metres depending on direction—so a flat-road pace calculator will overestimate your ability. The calculator gives a theoretical average pace, but real-world pacing must account for hills, aid stations, and fatigue.

How to Use the Calculator for Training

Most runners use the calculator in two ways:

• Check a goal time: Enter your target finish time (e.g., 11:00:00) and the official distance (e.g., 89 km). The result tells you the average pace you must hold. If that pace is faster than your current long-run pace, you need to adjust your goal or improve your fitness.
• Plan a cutoff strategy: Enter 12:00:00 as the finish time to see the minimum pace required just to finish. Many runners aim for a 11:30–11:45 finish to build a buffer for walking hills or unexpected stops.

For training, use the pace to set your long-run target. For example, if your goal pace is 7:30 min/km, your long runs should be at or slightly slower than that pace. Do not try to run every training kilometre at goal pace; most long runs should be 30–60 seconds per km slower.

Common Mistakes and Misconceptions

A frequent error is confusing pace with speed. A pace of 8 min/km is a speed of 7.5 km/h—they are reciprocals, not the same. Another mistake is using a 42.2 km marathon pace calculator and assuming it scales directly. Because of fatigue and hills, your average pace for 90 km will be significantly slower than for a standard marathon, even at the same effort level.

Many runners also forget that the cutoff is based on gun time, not chip time. The clock starts when the gun fires, not when you cross the start line. If you are in a later seeding wave, you may lose several minutes before you actually start moving. Add that buffer to your target finish time.

Finally, the calculator assumes you run a perfectly even pace. In reality, most runners slow down in the second half. Plan to run the first half slightly faster than average (but not too fast) and the second half slightly slower. A common strategy is to aim for 5–10 seconds per km faster in the first half, then let the pace drift.

Cutoff Times and Medals

The Comrades has a strict 12-hour cutoff. Runners who finish under 12 hours receive a medal; those who finish between 12 and 13 hours (if the race extends the cutoff) get a different medal, but the official race cutoff is 12 hours. The race also has intermediate cutoffs at certain points—like Drummond, Inchanga, and Umlaas Road—where you must reach by a specific time or be pulled from the course. These cutoffs are stricter than the overall pace, because they account for the hills. You cannot simply run an even 8 min/km and expect to make every intermediate cutoff; you need to be faster on the flats and downhills to bank time for the climbs.

For example, in the “up� run (from Durban to Pietermaritzburg), the cutoff at Drummond (about 42 km) is typically around 5 hours and 15 minutes. That is a pace of about 7:30 min/km for the first half, which is faster than the overall 8 min/km average. The calculator can help you see what pace you need for each segment, but you must adjust for terrain.

Alternatives and Adjustments

If you are training for a hilly course, a simple pace calculator is not enough. Consider using a pace calculator that includes elevation gain, or use a training plan that specifies effort levels (e.g., heart rate zones) instead of pace. Many runners use a “power� meter or RPE (rate of perceived exertion) on hills, because pace alone is misleading when the gradient changes.

You can also adjust the distance input to reflect a training run. For example, if you are doing a 30 km long run, enter 30 km and your target time for that run to see the required pace. This helps you practice holding a specific pace for a specific duration, which is more relevant than a single average over the full race distance.

Frequently Asked Questions

What is the exact distance of the Comrades Marathon?

The distance varies each year, typically between 87 and 90 km. The official distance is announced before the race and is measured by the race organisers. For 2024, the distance was approximately 89.2 km, but you should always check the official race website for the current year.

What is the cutoff time for the Comrades?

The official cutoff is 12 hours from the gun start. Runners who finish after 12 hours but before 13 hours may receive a “worse� medal, but the race is officially over at 12 hours. Intermediate cutoffs at specific points are stricter, so you cannot simply run an even pace.

Can I use a standard marathon pace calculator for Comrades?

No. The distance is more than double, and the hills and fatigue mean your average pace will be much slower. A standard marathon pace calculator will give you a pace that is too fast to sustain for 90 km. Use a calculator specifically for ultramarathon distances, or adjust your goal time significantly.

How much buffer should I add to my target finish time?

Add at least 10–15 minutes to account for the start line delay, aid station stops, and unexpected issues like stomach problems or blisters. If you are in a later seeding wave, add more—up to 20 minutes. The calculator gives you the raw pace; your actual target should include a buffer.

What pace should I run to finish in 11 hours?

For a 90 km race, 11 hours (660 minutes) gives an average pace of 660 ÷ 90 = 7.33 min/km (7:20 per km). That is a speed of 8.18 km/h. For an 87 km race, the pace would be 660 ÷ 87 = 7.59 min/km (7:35 per km). Always use the exact distance for the year.

Does the calculator account for hills?

No. It assumes a flat course. For the Comrades, you need to run faster on downhills and flats to bank time for the climbs. A good rule is to aim for 5–10 seconds per km faster than your target average on the first half, then allow the pace to slow on the hills.

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in t | Finish time | min | 50 | 0
in d | Distance | km | 10 | 0
out pace | Average pace | min/km | t / d | 2
out speed | Average speed | km/h | d / (t / 60) | 2