Running and fitness

Work out your pace, predict a finish time, add up splits and keep an eye on your weekly distance. Varlig understands minutes per kilometre and stopwatch times, so your training log reads the way you’d talk about a run.

Pace from any run

Write the distance, in, and the time it took. The answer is your pace per kilometre or per mile.

calc

10 km in 52 minutes gives 05:12/km

# Parkrun finished in 26:45

5 km in 26:45 gives 05:21/km

3 miles in 30 minutes gives 10:00/mi

# Pace for a half marathon under 2 hours

21.1 km in 1:58:30 gives 05:37/km

# Treadmill set to 12 km/h

12 km in 60 minutes gives 05:00/km

Write the time the way your watch shows it: 26:45, 27 min 30 s, 27.5 minutes and 1:58:30 all work. The same form turns a treadmill speed into a pace: 12 km in 60 minutes is 12 km/h. See Pace.

Finish times

Pick a goal pace and see the finish time it gives, and when your supporters should be at the line.

calc

# Half marathon at 5:30 per km, starting at 9:30am

goal pace = 5:30/km

half marathon = 21.1 km

finish = goal pace * half marathon gives 1 hour 56 min 3 s

finish as laptime gives 01:56:03

9:30am + finish gives 11:26 AM

# At 5:15 per km instead

half marathon at 5:15/km gives 1 hour 50 min 46.5 s

Write a pace the way your watch shows it, such as 5:30/km. Multiplying it by a distance, or writing the distance at the pace, gives a finish time, as laptime shows it like a stopwatch, and adding it to a clock time gives the time you’ll finish. See Finish times and distances from a pace.

Splits

Paste in your kilometre splits to see the total, the average and how evenly you ran.

calc

# Kilometre splits from a 5K

splits = [5 min 42 s, 5 min 35 s, 5 min 31 s, 5 min 28 s, 5 min 20 s]

sum(splits) gives 27 min 36 s

average(splits) gives 5 min 31.2 s

max(splits) - min(splits) gives 22 s

# Half marathon, first and second half

first half = 0:54:40

second half = 0:53:10

the difference between first half and second half gives 00:01:30

Lists keep their units, so the total and average of your splits come out in minutes and seconds. Each split here is faster than the one before, and the difference between shows the second half of the half marathon was a minute and a half quicker than the first. See Lists with units and Timespans, lap times and HMS.

Weekly distance

Add up the week’s runs, compare with last week and set a sensible limit for next week.

calc

# This week's runs

runs = [5 km, 8 km, 6 km, 14 km]

this week = sum(runs) gives 33 km

last week = 30 km

last week to this week as % gives 10%

# Build by no more than 10% a week

next week = this week + 10% gives 36.3 km

max(runs) / this week as % to 0 dp gives 42%

a to b as % gives the change between two weeks, and + 10% sets next week’s ceiling. The last line divides your longest run by the week’s total and rounds the share, so you can see if the long run is taking over. See Summary statistics and Percentage change.

A simple training plan

Count back from race day to find when to start, and see how quickly a long run can grow.

calc

# Half marathon on 25 April 2027, 12-week plan

race = 25 April 2027

weekday on race gives Sunday

plan start = race - 12 weeks + 1 day

plan start as EEE d MMM yyyy gives Mon 1 Feb 2027

# Long run in km, growing 10% a week from 10 km

map(round(10 * 1.1^w), w, range(0, 7)) gives [10, 11, 12, 13, 15, 16, 18, 19]

(time from 10 to 21.1 at 10% per week) rounded up gives 8 weeks

Subtracting weeks from a date lands on the same weekday, so adding a day turns race-day Sunday into a Monday start. map works out the long run for each week, and the last line shows that 8 weeks of steady growth reach the full distance, leaving 4 weeks to spare. See Adding and subtracting time and Map and filter.

Make it your own

Check a bike ride: 42 km / 1h 30m gives your average speed of 28 km/hour, and 2 hours at 25 km/h shows a longer ride covers 50 km.
Find how far a timed run takes you at a steady pace: 44 min / 5:30/km gives 8 km.
Following a plan written in miles? 5:00/km in min/mi gives 08:03/mi, and 5:30/km in km/h gives the treadmill speed.
Time your track reps: 400 m in 1:45 gives 04:23/km.
Keep a countdown to race day with whole weeks until 25 April 2027, which tells you how many full training weeks are left.
Heading out after work? 7.30pm + 52 min shows when you’ll be back.