50K Pace for 4 Hours — 4:48 per km (7:43 per mile)
50k pace for 4 hours — the answer is 4:48 per kilometre (7:43 per mile). Hold that pace from the start to the finish of the 50k and you will cross the line in 4 hours. This page shows the exact arithmetic, the splits that keep you on target, what that pace feels like, and how to train for it.
A pace is not a guess and not an average of opinions: it is time divided by distance, and for a fixed distance and a fixed finish time there is exactly one answer. What varies is how hard that pace is for you, how evenly you can hold it, and what training turns it from a number on a page into a result on race day. That is what the rest of this page is for.
A 50K ultramarathon is the standard first ultra: 50 km of running where walking the hills, eating on the move, and managing the second half matter more than speed.
Work out your own pace
Use the pace calculator to check any target time at this distance — enter your goal and it returns the pace per kilometre and per mile, plus the splits. The general pace calculator does the same for any distance, and converts between pace, speed, and finish time. Pace itself is an exact calculation, so the tools agree with the figures on this page to the second.
The formula, shown and cited
Pace per kilometre = finish time ÷ distance (km)
Pace per mile = finish time ÷ distance (miles)
The distance used here is the official standard: the 50k is 50 km (31.07 miles), following the World Athletics standard distances — the marathon is 42.195 km and the half marathon 21.0975 km, and the shorter track distances are exact metric distances. One mile is 1.609344 km, which is why the per-mile pace is always slower numerically than the per-kilometre pace.
Working it through for this page:
4:00:00 ÷ 50 km = 288.0 seconds per km = 4:48 per km
4:00:00 ÷ 31.07 miles = 463.5 seconds per mile = 7:43 per mile
Your average speed for the whole effort is 12.50 km/h (7.77 mph). Speed and pace are the same information expressed two ways — runners talk in pace because it maps directly onto splits and watch readings, while speed is what cyclists and the physics use. Neither is an estimate: given the distance and the time, both are exact.
Your splits for 4 hours
Even pacing at 4:48 per km gives these 5 km splits (with the final partial split at the finish):
| Distance | Cumulative time |
|---|---|
| 5 km | 24:00 |
| 10 km | 48:00 |
| 15 km | 1:12:00 |
| 20 km | 1:36:00 |
| 25 km | 2:00:00 |
| 30 km | 2:24:00 |
| 35 km | 2:48:00 |
| 40 km | 3:12:00 |
| 45 km | 3:36:00 |
| 50 km | 4:00:00 |
Splits are the practical half of pacing. A watch showing 4:48 per kilometre tells you nothing unless you know the cumulative time you should see at each marker, and the table above is that checklist. The classic error at every distance is starting 10 to 15 seconds per kilometre too fast in the first quarter and paying for it twice over in the second half — even pacing, or a very slight negative split (second half a touch faster than the first), is the fastest way to hit a target time for almost every runner.
For the 50k, that means resisting the crowd in the opening kilometre. If your first split is faster than 4:48 per km, you have not banked time; you have borrowed it at a high interest rate, and the debt comes due as heavy legs and a rising heart rate later. Check the table at each marker, correct gently (a few seconds per kilometre, not a sudden surge), and trust the plan.
What 4:48 per km means
This is a strong recreational pace — a strong recreational pace — the level of a committed runner who trains three to five times a week and races regularly. In training terms, your easy running should sit around 6:03 per km (roughly 60 to 90 seconds per km slower than this target), your tempo running around 5:08 per km, and your interval work faster than target pace in short repetitions with full recoveries. Those three gears are the whole of a training week: easy volume builds the aerobic base, tempo work lifts the speed you can sustain, and intervals lift the ceiling.
As a cross-check, the Riegel formula (Riegel, 1981: predicted time = known time × (new distance ÷ known distance)^1.06) translates this performance to other distances, assuming equal fitness and similar conditions: about 20:54 for 5K, 43:35 for 10K, 1:36:10 for a half marathon, and 3:20:29 for a marathon. Treat those as estimates, not promises — Riegel is least reliable when the jump in distance is large, and it says nothing about whether you have done the long runs a marathon actually requires.
How to train for this target
Build the week around one long run, one quality session, and easy days. For the 50k, the long run should reach at least the race distance (or 75 to 90 minutes for the shorter events) at easy pace, 6:03 per km or slower, with the last few long runs including 20 to 30 minutes at target pace so the effort feels familiar. The quality session alternates weekly between tempo running — 20 minutes continuous at 5:08 per km — and intervals at faster than target pace, such as 6 × 800 m with 90 seconds of jogging recovery for middle distances, or 5 × 1 km at target pace for the longer races.
Add two or three easy runs of 30 to 45 minutes between the hard days, and keep at least one full rest day a week. Increase total weekly volume by no more than about 10% a week, and cut volume by 30 to 40% in the final week before the race (the taper) so you arrive fresh rather than fit-but-tired. Strength work twice a week — squats, lunges, calf raises, core — supports the running without replacing it, and a warm-up of 10 minutes easy plus strides before every quality session reduces injury risk.
On race day, eat a familiar breakfast two to three hours beforehand, sip water rather than gulping it, and start at 4:48 per km from the first step. For efforts over 75 minutes, practise taking on carbohydrate during the long runs — roughly 30 to 60 g per hour — because the gut needs training just like the legs. And remember the safety frame for everything on this site: training targets are estimates, not medical advice, and daily intakes below 1,200 kcal (women) or 1,500 kcal (men) need medical supervision.
What the pace does NOT tell you
Pace is exact, but it is not the whole story. The same 4:48 per km feels very different on a flat road, a hilly course, a hot day, or into a headwind — heat alone can add 10 to 30 seconds per kilometre, and hills more. Course measurement also matters: a GPS watch typically reads 1 to 2% long on a twisty course, so a watch pace can look slower than the official chip time suggests. Trust the course markers and the table above over the watch when they disagree.
Pace also says nothing about how you got there. Two runners can hold 4:48 per km with very different heart rates, cadences, and fuel needs, and the Riegel equivalents above assume equal fitness across distances — a sprinter's 5K does not predict their marathon, and a marathoner's 800 m is a poor guide to their 5K. Finally, a target time is a goal, not a verdict: missing it by a minute after a well-run race is a training signal, not a failure, and the right response is to look at the splits, find where it slipped, and adjust the next block.
Related pages
- Pace hub
- 50 Miles Pace for 8 Hours — 5:58 per km (9:36 per mile)
- 100K Pace for 11 Hours — 6:36 per km (10:37 per mile)
Frequently asked questions
What pace do I need for the 50k in 4 hours ?
4:48 per kilometre, which is 7:43 per mile. That is the exact figure: 4:00:00 divided by 50 km. Hold it evenly and you finish in 4 hours ; the splits table above shows the cumulative time to expect at each marker.
Is 4:48 per km fast?
It is a strong recreational pace. For context, easy running for a runner targeting this time would be around 6:03 per km, and tempo running around 5:08 per km. Whether it feels fast depends on your current fitness — compare it with your recent race paces rather than with anyone else's.
What should my 5K time be if I can run the 50k in 4 hours ?
The Riegel formula predicts about 20:54 for 5K from this performance, and about 43:35 for 10K. Those are estimates assuming equal fitness and similar conditions; the further the distance from your known result, the less reliable the prediction.
How do I pace the 50k so I hit 4 hours ?
Run even splits at 4:48 per km, using the cumulative times in the table above at each marker. Do not start faster — the first kilometre should feel almost too easy. If you are a few seconds slow at halfway, correct by a few seconds per kilometre, not with a sudden surge.
What training do I need to run 4:48 per km for the 50k?
A week with one long run, one tempo or interval session, easy runs between, and one rest day, built over 8 to 12 weeks with volume rising by about 10% a week. Include 20 to 30 minutes at target pace inside the long run in the final weeks, and taper in the last week.
Does weather change the pace I should aim for?
Yes. Heat, humidity, hills, and wind all slow the same effort, by 10 seconds per kilometre or more on a hot day. On a difficult day, run by effort and the splits will be slower — that is the correct adjustment, not a failure of fitness.
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.