Marathon pace chart

Using the chart on race day

Pick your goal row. The pace columns are what to hold. The three split columns are checkpoints to compare against as you pass them.

The checkpoints catch drift early. If you reach 10K a minute ahead of the chart, you are running about six seconds per kilometer too fast. That is worth correcting while it is still cheap.

The 30K column matters most. It is the last checkpoint before the final 12 km. Arriving there on schedule, not ahead of it, leaves room for that stretch.

Look at the 10K and 30K columns together and you will see that 30K is not always exactly three times the 10K figure. Each one is rounded on its own, from the unrounded pace, so they can differ by a second.

Common goals

Every figure below is a row of the chart. The paces are rounded to the nearest second, so a few of them land a fraction slow. Where that happens it is noted, and the fix is to run a shade quicker than the number shown.

Sub-3 marathon

The pace is 4:16/km, or 6:52/mi. Halfway comes at 1:30:00, 10K at 42:40 and 30K at 2:07:59. The 4:16 is rounded up from the exact figure, so holding it to the line misses by a couple of seconds. Aim to run a touch under it.

Sub-3:30 marathon

The pace is 4:59/km, or 8:01/mi. Halfway at 1:45:00, 10K at 49:46, 30K at 2:29:18. This one is rounded up too. Holding 4:59 all the way finishes outside 3:30, so aim a touch under it.

Sub-4 marathon

The pace is 5:41/km, or 9:09/mi. Halfway at 2:00:00, 10K at 56:53, 30K at 2:50:38. Here 5:41 is rounded down, so holding it exactly does get you under four hours, with seconds to spare.

Sub-4:30 marathon

The pace is 6:24/km, or 10:18/mi. Halfway at 2:15:00, 10K at 1:03:59, 30K at 3:11:58. The 6:24 is rounded up slightly. Held exactly, it finishes just over 4:30.

None of this margin survives a wide line through the course. Crowds and bends add distance, and your watch will count it. Use the checkpoint times, which are tied to the course markers, rather than the pace on your wrist.

Negative split example

A negative split means a slower first half and a quicker second half. The marathon pace calculator builds one with a single number: the offset in seconds per kilometer. It adds the offset to the even pace for the first half and takes it off for the second.

Take a four-hour goal with a 5-second offset. Even pace is 5:41/km. The first half is run at 5:46/km and the second at 5:36/km.

The two halves are 2:01:45 and 1:58:15. Add them and you get 4:00:00 exactly. The extra 5 seconds per kilometer on the way out costs about 105 seconds over 21.0975 km. The 5 seconds saved on the way back returns exactly the same amount.

That is the whole method. Equal and opposite changes over two equal distances cancel out, so the goal time never moves. Only the checkpoints shift. At 30K the negative-split runner is about a minute behind the even-pace runner, and has 12 km of quicker running left to close it.

The calculator caps the offset at 60 seconds. A big offset makes the second half much harder than the first, which is a very different race from the one the goal time suggests.

What the chart can't plan for

A chart is pure arithmetic. It assumes a flat course, still air and a body that holds steady for hours. Real marathons have hills, heat and late-race fatigue, and any of them can cost minutes.

Base your goal on recent training and race results, not on the row you would like to hit. The race time predictor turns a shorter race into a marathon estimate, which is a sensible place to start.

The figures here are pacing arithmetic, offered as general information, and should not be taken as coaching or medical advice. Before marathon training, ask a doctor if your heart or lungs need medical care, or if you are returning after injury or illness. The same applies if you have never run long distances.