Race Pace Calculator

The race pace calculator shows the pace you need to hit a goal time for a 5K, 10K, half marathon or marathon. It gives the average pace per mile and per kilometre, plus the time for each half and a split for every mile or km. It runs in your browser, is free, and needs no sign-up. Nothing you type is uploaded or stored on a server.

Use it to plan a race before you run it. You can compare even pacing with a negative split or a positive split, and see exactly how each choice changes your halves and your mile or km splits. Whether you’re planning a first marathon or aiming for a personal best at 10K, the same steps apply.

The page opens with a marathon and a goal time of 4:00:00, so a full set of results is visible straight away.

How to use the Race Pace Calculator

1. Choose your race. Select 5K, 10K, half marathon or marathon.
2. Enter your goal time. Type the finish time you want to run.
3. Pick a pacing plan. Choose Even, Negative split or Positive split.
4. Set the difference between halves. If you chose a negative or positive split, pick a value from 0.5% to 10%. A bigger number makes the gap between your two halves wider.
5. Select your units. Switch between miles and km. Every pace and distance changes to match.
6. Read the results. Check your average pace, your first-half and second-half times, and the pace of each half. Then scroll through the split table to see the split time and elapsed time for every mile or km.

Use the buttons below the results to get more from your plan. Print splits creates a printable copy of your split table. Copy link shares or bookmarks the exact result, because your settings are kept in the page address. Make a pace band for this time takes your goal time to a pace band. The miles/km choice is remembered in your browser. On a phone, wide tables scroll sideways inside their box.

After each change, read the results again from the top, since the average pace, both halves and the split table all update together.

How do I calculate my race pace?

Your race pace is your finish time divided by the race distance. For a 5K, 10K, half marathon or marathon, the calculation is the same: total time ÷ distance. A marathon is 26.2 miles or 42.195 km, and a half marathon is 13.1 miles or 21.0975 km.

For example, a marathon goal of 4:00:00 is 240 minutes. Divided by 26.2 miles, that gives about 9:09 per mile. A half marathon goal of 2:00:00 also works out to 9:09 per mile, or 5:41 per km. A 10K goal of 50:00 is 8:03 per mile. The race pace calculator does this arithmetic for you and works in both units.

What is a negative split?

A negative split means you run the second half of a race faster than the first half. A positive split is the reverse, where the first half is faster. Even splits give both halves the same time. In every case, the two halves add up to your goal time.

The tool’s example shows how this works. For a marathon goal of 4:00:00 with a 2% negative split, the first half is 2:01:13 and the second half is 1:58:47. Together they still total 4:00:00. The first half is slower, so you start more conservatively and finish with a faster second half. The difference between halves controls how big the gap is, so you can try small or large changes before you run.

How do I read the split table?

The split table has one row for every mile or km of the race. Each row shows the time for that split and the elapsed time at that point, so you can compare your watch with the plan at each marker. For now, the splits assume an even pace across the distance, so the table does not allow for hills or a slow section of the course.

What does the difference between halves change?

The difference between halves sets how far apart your two half times are. You can choose a value from 0.5% to 10%, and a bigger number widens the gap. The two halves always add up to your goal time, so a larger gap means a slower first half and a faster second half for a negative split, or the reverse for a positive split. In the tool’s 2% negative split example for a 4:00:00 marathon, the first half is 2:01:13 and the second half is 1:58:47. Use the two half times to judge whether the gap feels right before race day.

Frequently asked questions

Should I run even splits?

Even splits are the simplest plan. They give you one steady pace to aim for, which makes them easy to follow on race day. A negative split can suit runners who feel strong late in a race, but it needs enough control in the early miles to avoid going out too fast.

How do I use a split calculator for a marathon?

Choose Marathon, enter your goal time and pick a pacing plan. The results show your average pace, the time for each half, and a split for every mile or km. Use the split table as a checkpoint list during the race.

Can I print my splits?

Yes. Click Print splits to print the split table for your goal time. Use the miles/km switch first if you want the printout in a specific unit.

Are course-adjusted splits from a GPX file available?

Not on this page. The splits assume an even pace across the distance. For a hill-adjusted band, see the Boston Marathon elevation profile and pace band; the RunPacePlan app will build one from your own GPX file for free.

Is my goal time saved or sent anywhere?

No. The calculator runs entirely in your browser. Nothing you type is uploaded or stored on a server, and you do not need an account. Your settings are kept in the page address, so sharing that link shares your result.

Can I use it for a race other than these four?

The race menu only offers 5K, 10K, half marathon and marathon. For another distance, the race time predictor accepts other race distances as its input.

Does the page work on a phone?

Yes. On small screens, wide tables scroll sideways inside their own box.

Related tools

• Marathon pace band: Use this when you want a printable card of paces to carry on race day.
• Marathon pace chart: Use this to compare marathon finish times with their paces at a glance.
• Race time predictor: Use this to estimate a likely finish time from a recent race result.
• Pace calculator: Use this to convert a time and distance into a pace, or work out a finish time from a pace.
• Sub 4 hour marathon pace: Use this to plan splits for a sub-four-hour marathon goal.
• Half marathon pace chart: Use this to see half marathon paces for a range of finish times.
• Training pace calculator: Use this to find easy, steady and hard training paces based on your fitness.
• mph to minutes per mile: Use this to turn a treadmill speed in mph into a pace per mile.