I have referred to before, but not set out in full, my Top Ten Tips for calculating marathon times. They are:

- The par time is 2 hours plus your age in minutes, plus another 10% if you are female.
- This will be achieved, after a year or so of effective training, if, in the last 13 weeks before the race - excluding the week of the race but counting the miles in all 13 calendar weeks prior to that - you’ve recorded an average of 55 miles per week.
- More mileage than that contributes nothing. But for every mile per week less than 55, add one minute to your race time.
- Provided, though, you’re not overweight. Par weight for men is 2 lbs per inch of height minus 5 lbs; for women 2 lbs per inch minus 15. Every pound over these weights adds 2 seconds per mile to your pace, say a minute to your marathon time.
- Weather: add 2 seconds per mile for every degree (Celsius) by which shade temperatures exceed 18 deg C.
- If it’s humid as well as hot, add 1 second per mile for every percentage point the relative humidity exceeds 65%.
- On a windy day, add 1 second per mile for every mile per hour that the headwind exceeds 10mph : deduct 1 second per mile for every 2mph that the tailwind exceeds 20mph.
- If the race director describes the course as "testing", "undulating", or more honestly "hilly", add anything up to 5 minutes. e.g. the Sheffield course carries a handicap of 3 minutes for the 3 hour runner.
- Now the positive bit. If you average, over the 13 weeks (see 2), one (short) hill times 10 repetition session or one (short) speed session per week, take off 4% from whatever 1 to 4 calculates to. For an average 1½ sessions per week, take off 8%. For 2 hill/speed sessions per week, take off 12%.
- That’s it. But you can throw it all away by going faster at the start than the calculated pace and trying to put "minutes in the bank". Remember minute banks charge at least 4 times as much for overdrafts as they allow on deposits, every second per mile you run too fast in the first 10 miles will cost you at least 4 seconds per mile in the last 10 miles.

But, I hear you say, "I’m not into running marathons". I guess you’re not into running 100km either, but use the following table to calculate your race pace - and by extension, your finishing time - at distances other than marathons:

Distance Mile 5km 10km l0mi ½mar 20mi Mara 100km Distance (miles) 1.00 3.11 6.21 10.00 13.11 20.00 26.22 62.10 Mile Pace Ratio 1.00 1.05 1.10 1.12 1.15 1.18 1.20 1.37

Use the Top Ten Tips, using just items 1,2,3,4 and 9 to work out what your marathon time would be if you trained for it properly and had no adverse conditions. Divide by 26.22 to give your mile pace for the marathon. Then divide by the "Mile Pace Ratio" 1.2 to tell you what pace you could run a (track) mile if you trained properly for that. Now, select your distance, multiply the track mile pace by the distance in miles and the mile pace ratio, press the buttons on the calculator and you’ve got your answer.

E.g. if your marathon time, using the Top Ten Tips, calculates to 3hr 3min, then your 10 mile time calculates as follows

183*1.12* 10.00 = 65.14 mins = 65min 9secs 26.22 1.20