Marathon Pace Calculator & Pace Band

A 4-hour marathon is a 9:09/mi average; going 1% negative starts you at 9:15

To run a marathon (26.2 miles, 42.195 km) in 4 hours, you need to average 9:09 per mile. Hold that pace from the gun and you hit 1 mile in 9:09, 5 miles in 45:46, 10 miles in 1:31:32 and the halfway point in 2:00:00. If you plan a second half that is 1% faster than the first, you start at 9:15/mi, pick it up by about 0.42 seconds every mile and finish at 9:04/mi. The first half then takes 2:00:36 and the second 1:59:24, and at the halfway point you are 36 seconds behind a runner who holds an even pace.

The calculator above turns a goal time into a plan you can actually use on race day. Pick a pace split (even, negative or positive) and it gives you the elapsed time to hit at every checkpoint. Enter how far your watch read at the end of a past race and it gives you the pace to hold on the watch face. Add your start time and it shows the clock time you will pass each marker, which is handy for anyone cheering on the course, and you can save the whole plan as a pace band image to cut out and wear on your wrist. If all you need is to convert between distance, time and pace, the running pace calculator is simpler.

Why plan your pace before race day

The most common marathon mistake is starting faster than goal pace because you feel fresh. A study of 91,929 finishes from 14 U.S. marathons in 2011 found that runners' second-half pace was on average 15.6% slower than their first-half pace for men and 11.7% slower for women, and the slower the finishing time, the bigger the slowdown (Deaner et al. 2015). For a 4-hour finisher who fades by 15.6%, that works out to a first half of 1:51:19 (8:29/mi) and a second half of 2:08:41 (9:49/mi): the runner banked 8 minutes 41 seconds on an even-pace schedule by halfway and then paid it all back.

An analysis of 1.7 million recreational finishes reported that runners who started too fast generally finished with slower times, while runners who finished too fast had usually held back too much earlier and lost time (Smyth 2018). A study built on more than 4 million results found that, among about 1.93 million runners analyzed, 28% of men and 17% of women hit the wall and slowed sharply late in the race (Smyth 2021). Writing your checkpoint times down before the start lets you see an early surge in numbers and back off right away.

• Preparing for a first marathon or half: choose even pace and build a band with 5-mile checkpoints so you can catch early over-pacing.
• Chasing a time like sub-4 or sub-3:30: tap the goal-time chip, pick −1% to −2% for the second half, and check your starting pace and halfway split.
• Your watch keeps disagreeing with the mile markers: enter the distance your watch showed at the end of a past race to get the pace to run by the watch face.
• Friends or family tracking you on the course: add your start time and the time it takes to reach the start line, copy the table and send it so they know roughly when you will pass each point.

How to use the calculator

1. Choose a distance: tap 5K, 10K, Half or Marathon, or type any distance. Use the unit switch for kilometres or miles.
2. Enter your goal time: type hours, minutes and seconds, or tap one of the goal-time chips for that distance (3:00 to 5:00 for the marathon, for example). If you leave hours empty, minutes can go above 59 (50 minutes = 50).
3. Pick a pace split: even (0%), faster second half (−1% or −2%), slower second half (+2%), or any value from −10% to 10%. A −1% split means the second half of the race takes 1% less time than the first half.
4. Add watch error (optional): enter how far your watch read at the end of a past race (for example 26.47 mi, or 42.6 km, for a marathon). The error percentage is worked out for you, and the big number switches to the average pace to hold on your watch.
5. Make your band: enter your start time and the time it takes to reach the start line, choose an interval of 1 or 5 (miles or kilometres), then press Save band image or Copy table. The address bar link carries your current values, so you can reopen the same plan later.

How the numbers are calculated

first half = T ÷ (2 + s) second half = T − first half elapsed(x) = a·x + b/2·x·(x − D)

T is your goal time, D is the distance and s is the pace split (−0.01 for −1%). The average pace a is T ÷ D, and the two halves are divided so that the second-half time is (1 + s) times the first-half time. The calculator assumes pace changes in a straight line with distance from start to finish, so the change per unit of distance, b, is 4 × (second half − first half) ÷ D². The elapsed time at distance x is then the formula above, and the gap to an even pacer is b/2·x·(x − D), which is largest at the halfway point.

Watch error e assumes your watch measures the official distance as (1 + e) times as long. The pace shown on the watch is the official pace ÷ (1 + e). If your watch read 42.6 km (26.47 mi) at the end of a past marathon, the error is 0.96%, and for a 4-hour goal the average pace on the watch is 9:04/mi against an official 9:09/mi. The band and table show elapsed times at the official distance markers on the course, so they stay the same whatever your watch reads.

Pace and halfway split for common goal times

These tables use a second half that is 1% faster than the first (−1%). Even pace is the average pace you would hold from start to finish. Paces are rounded to the second.

For a 4-hour marathon with a −1% split and a 7:00 AM start, here are the elapsed time and clock time at every 5 miles. Clock times are rounded to the minute.

Even, negative or positive split: which to choose

A bigger negative split is not automatically better. In a 4-hour marathon, −1% makes the halves differ by 1:12 and −2% by 2:26, and at halfway you are 36 seconds and 1:13 behind an even pacer respectively. As the research above suggests, finishing far too fast can mean you held back too much early (Smyth 2018), so if you have never practised picking up the pace late in a run, starting at even or around −1% is a gentler choice. Use a positive value not as permission to slow down, but to account for conditions you cannot avoid, such as hills or heat.

Why your watch reads more than 26.2 miles

A certified road course is measured along the shortest possible route a runner could legally take. The World Athletics measurement guidelines have the measurer ride a line 30 cm (about 1 foot) from the curb or any solid edge, hugging the inside of every turn, and then add 0.1% to allow for measurement error, so every kilometre comes out at 1,001 m (the short course prevention factor of 1.001). Even the shortest line on a certified course is therefore slightly longer than 26.2 miles, and if you swing wide around other runners, the distance you actually cover grows further.

GPS error comes on top of that. The Hartford Marathon, which uses a USATF certified course, tells runners that a typical GPS device is off by 1% to 2% and that it is not unusual for a watch to read 26.50 miles (about 42.65 km) or more on a certified course. On the other hand, a study that tested eight sports watches over distances from 404 m to 4.3 km found they generally measured short in city and forest conditions, with mean absolute errors of 3.2% to 6.1% (Gilgen-Ammann et al. 2020). Direction and size differ by watch and by course, so the distance your own watch showed at the end of a similar past race is the most reliable number to enter.

• If your watch reads long, matching its average pace to your goal pace on the screen will leave you finishing late. With a watch that reads 26.47 mi (42.6 km) for the marathon, holding the 4-hour even pace of 9:09/mi on the watch face means you finish about 2 minutes 18 seconds late.
• Auto-laps arrive before the course markers. At the 20-mile sign, that watch already shows about 20.19 miles.
• The band uses the official markers. When you pass a sign, compare your watch time with the band and you will know whether you are on plan, whatever the watch distance says.

Clock times and the walk to the start line

Big races release runners in waves, so it can take several minutes after the gun to cross the start line. Your chip time normally starts when you cross the timing mat at the start line, so use the band's elapsed times as they are and add the wait only when working out clock times. For example, with a 7:00 AM gun and 6 minutes to reach the start line, every clock time in the table above is 6 minutes later. If a cutoff or a placing is based on gun time, check the race rules as well.

Making a wrist pace band

Save band image saves a PNG that shows the elapsed time for each checkpoint as a strip (and the clock time as well if you enter a start time). When there are many checkpoints, the strip is split into several rows with the same number of columns. Print it, cut along the dotted line and wrap it in clear tape on your wrist or watch strap, and it will survive sweat and rain. A 5-mile interval matches most timing mats and is easy to read; a 1-mile interval helps you spot early over-pacing sooner. To keep it on your phone instead, use Copy table and paste the text table into a message.

Common mistakes

• Treating 21 km as the halfway point: a half marathon is 21.0975 km (13.1 mi). At a 4-hour even pace, 21 km and the true halfway point are 33 seconds apart.
• Counting the walk to the start line as running time: your watch starts as you cross the line, so the band's elapsed times exclude the wait. The start-line time is added only to the clock times.
• Watching only your watch's average pace: if the watch reads long, a screen average that equals your goal still means a late finish. Check the band's elapsed time at the course markers too.
• Keeping the same plan on a hot day: marathon times got steadily slower as wet-bulb globe temperature (WBGT) rose from 5 to 25 °C, and slower runners lost more (Ely et al. 2007). In the heat, set a slower goal time or use a positive split and rebuild the plan.
• Using an even plan on a hilly course: the calculator assumes flat ground. On climbs, run by effort rather than pace and use the elapsed time at the markers to check the overall flow.

Limits of this calculation

A pace that changes smoothly with distance is a simple model for planning. In a real race, hills, wind, aid stations, toilet stops and crowded stretches move individual splits up and down by a few seconds. Watch error is also treated as spread evenly over the course, when in reality it clusters in tunnels, among tall buildings and on sharp corners. The result is a reference table for reaching a goal, not a prediction that guarantees a time. To judge which goal is realistic for your current fitness, start with the race-time prediction in the running pace calculator.

As of 2026-10-19 · Course measurement rules follow the 2023 World Athletics and AIMS measurement guidelines; research figures are the values confirmed in the abstracts and full texts of the sources below.

Sources

• 01World Athletics · AIMS. The Measurement of Road Race Courses (2023)Shortest possible route, 30 cm from the curb, short course prevention factor 1.001
• 02Deaner RO, et al. Men are more likely than women to slow in the marathon. Med Sci Sports Exerc. 2015;47(3):607-61691,929 results from 14 U.S. marathons; second-half pace slowdown of 15.6% for men and 11.7% for women
• 03Smyth B. Fast starters and slow finishers: A large-scale data analysis of pacing at the beginning and end of the marathon for recreational runners. J Sports Anal. 2018;4(3):229-2421.7 million recreational finishes; both too-fast starts and too-fast finishes cost time
• 04Smyth B. How recreational marathon runners hit the wall: A large-scale data analysis of late-race pacing collapse in the marathon. PLoS One. 2021;16(5):e0251513More than 4 million results; 28% of men and 17% of women hit the wall
• 05Gilgen-Ammann R, et al. Accuracy of Distance Recordings in Eight Positioning-Enabled Sport Watches: Instrument Validation Study. JMIR Mhealth Uhealth. 2020;8(6):e17118Generally measured short in city and forest conditions; mean absolute error 3.2% to 6.1%
• 06Hartford Marathon Foundation. Course Length – USATF Certified CoursesGPS usually off by 1% to 2%; 26.50 miles or more on a certified marathon is not unusual
• 07Ely MR, et al. Impact of weather on marathon-running performance. Med Sci Sports Exerc. 2007;39(3):487-493Performance steadily slower from WBGT 5 to 25 °C, with slower runners losing more

Frequently asked questions

Related tools