What is the half marathon equivalent of the "20 mile long run" in marathon training?

I’d say 100-120 mins.

I think once you can hit 15-16 at a solid pace you’re ready to race a good half marathon.

If it’s more of an “I’m just trying to finish without walking” scenario, building up to 10 is great.

Well Nick Willis, a miler, does 18 mile long runs so…

Training for half marathon:

15-20 mile long run

When will you americans realize that nobody else in the world cares about how many "miles " you run .Interweb is global and athletes train using Kilometers to measure distance.

There isn't a defined great length for an LR because it doesn't matter that much. What matters is how well your threshold is and how used to a strong consistent effort you are. The higher your mileage, the more so it isn't important. You could probably have great success off runs no longer than an hour. Now, what's optimal? Probably 2 hours most weeks with a longer one once a month or so. But if you can't set aside the appropriate recovery, focus more on the workouts that matter and double a lot.

I'm at 1:19-1:20 so I do a 7-10 mile tempo at 6:30.

Long runs I do every week anyway but much slower.

Run should be 144 furlongs, give or take a few. If you want to go sub-0.00148 fortnights in the half, around 19892 furlongs/fortnight should feel very easy.

Sub-0.004465, I I meant. Everyone knows a sub-0.00148 fortnight half is preposterous.

The half is more like a 10k than a marathon, so just train the same as you would for a good 10k.

So your long run will probably be 12-15M

If looking at it from a time perspective, how much longer than 1/2 Mar race time?

I would say the sweet spot is 15-18 miles (obviously how fast you are running is part of the equation). Alternate some hilly, longer 18 mile runs more for strength & endurance and then do some 15 milers with some race intensity or as a progression.

And Jakob a 1500/5000 runner never runs above 13 miles. There isn't a one size fits all approach.

That's not a tempo... Tempo is more like a 5km-10km pace effort. That's more like marathon pace effort.

Unlike marathon training, your HM long run will be longer in duration than the goal race. And the pace will be far from the goal pace. So it is in no way a specific workout, but still useful for general endurance. Hence your limiting factor in the 2-3 months before the goal race would be recovery time so that you can nail the more specific workouts. 'All the way up to 20' might be from base building phase of an athlete who likes to go long and takes this kind of run well. Does anyone running HM at high level really do that much peaking for a HM?

It can be argued that an easy 32K long run wouldn't be specific for marathon either, but it's the only type of run when you spend about the race duration running, and if you push the pace just a little it can be like 80% of marathon effort, so really much closer.

20 miles

Also wrong... A tempo isn't 5K-10K pace effort, it's usually 5K-10K distance (20-40min) at a moderately hard effort. It's usually between 10K-half marathon pace, leaning towards the latter. 10mile pace is usually a good starting point. No one does a 10K tempo at 10K pace let alone 5K...

To answer OP's question. It depends. If you're trying to finish, 10 miles is usually fine. If you're trying to nail down goal times, then I like 16-18 miles. Over-distance is helpful for a HM since it's more like a 10K race than a marathon.

20 miles really isn't a long enough long run for marathon training, but may be sufficient for the half