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# McMillan calculator times

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I just wondered what you guys are looking at for the fetch predictions. One page, the Riegel calculator, updates the exponent used for race time calculations based on your logged pbs at all distances, so the point that one's marathon is slower than the 5 km predicts is allowed for by raising the exponent. For example, the default Riegel exponent is 1.06 whereas mine is 1.08, meaning I take a bit longer for marathons than I should.

The fetch calculator itself is here. It's not clear whether it uses the Riegel number it calculates on the other page.

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Steve, I originally linked to this one, which is based on the Riegel formula but modified based on a survey of real results, and give a less optimistic conversion (better for women than for men).

The OP went straight to the fetch calculator for all distances that you've linked to, which gives an even faster marathon prediction than the McMillan calculator.

• my 5k and half-marathon PB's were set in last few months (21.40 and 1.40.25) and match the Mcmillan calculator pretty much spot-on (not that I was aiming to do this). suggests it's fairly accurate to me. as the Mcmillan predicts 45.00 for 10k, this is now my next target.

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I don't get involved in marathons, but for a laugh put my half pb into that fetch calcualtor, and it whacked out a 2:43:xx marathon.

My pal who does do marathons has a half pb within about 10secs of mine, and just came out 2:43:xx at London.

So that one example works well

• literatin wrote (see)

Someone on the P&D thread 'helpfully' posted the link to it the day before and I'm pretty sure it was offering me a slower prediction based on my half time than it is now.

The Dastard!!!!   I really hope you never let him forget about that indiscretion as long as he lives!   Tsk!

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Well, I didn't name and shame him.

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Thanks, L - wasn't aware of that one.

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