Best app/watch that provides instantaneous pace (ie not just average)

You think you want instantaneous pace, but you really don't. Think about it: speed is distance divided by time. Watches measure time with insane accuracy, but they estimate the distance you cover based on signals from satellites hundreds of miles away in space that get refracted through the atmosphere. Instantaneous pace readings on even the best watches are all over the place and not actually useful.

What you want is your current lap pace. On most watches, you can set a lap distance to a mile or a kilometer or even a custom distance. Your current lap pace shows you your pace for your current mile/km so far. It may not be perfectly accurate at the start of each lap, but pretty soon it's close enough. As you run and check your current lap pace, you'll get a sense for how it reacts.

And in a race, it's invaluable. It'll help you back off a bit when you're 400m into a half marathon, and help you stay patient at mile 8 in a marathon when you feel invincible.

My Garmin does give live pace readings. You have to set screen for that parameter. It is pretty accurate, despite what above poster says, on my bike in any case, and even if used in car to check speedo

This is the correct answer. Virtually any brand of GPS watch will give you your current pace, or lap pace. Current pace is often virtually useless for running due to variability of the GPS measuring distance. Current pace typically will jump around too much, often by 30+ seconds per mile. So, if you are running 7 min mile pace, the watch might say 6:30 pace, and you will look down 5 seconds later and it might say 7:15 pace, and this will go on and on with significant swings with current pace. I do not know why watch manufacturers do not sample over a period of time say 30 seconds or a minute for current pace as that would improve accuracy substantially, or maybe someone does now and I am not aware. Until someone figures this out lap pace is the best alternative.

The cheaper Garmin I had in 2012 only had average pace, no current lap pace. That was awhile ago now though.

Just make sure your watch can do current lap pace, that's what you need. As has been mentioned above.

If you get something like a Coros with the foot pod 2, that will give instantaneous pace.

coros.com

COROS POD 2 - Run Beyond GPS

Next level accuracy for all runners.

Link:coros.com/pod2

I don't know whether Garmin or Suunto has something similar, but the Stryd power meter is (I believe) compatible with Garmin and you could check whether it does instant pace.

For this, Garmin watch >> Apple Watch but if you get the Apple Watch, the built in app is the way to go.

The DC Rainmaker website is always helpful too.

I agree with this. Instantaneous pace isn't helpful for running; it's too volatile. Look at any run on strava or garmin connected, and you'll see a very noisy graph. You would spend your whole run bouncing between thinking you're running too fast or too slow.

Lap pace is a better snapshot for pacing. I use it in workouts and races all the time. It might be a little off at the beginning of a lap, but that can actually be valuable because it typically shows how you ended the previous lap. For example, you're targeting 6:00 pace, and you hit right on the money, but the next lap starts showing 6:15 pace. That means you probably were slowing down toward the end of the last split.

Pretty sure all of the current Garmin devices have both current pace and lap pace. If you use pace on a track, make sure you're using track mode on Garmin devices.

I second this. I pair my Stryd to my Garmin 245m and it works. Also works with Apple watch/Stryd.

As said above, get a foot pod, they provide a much more stable current pace and don’t have the 30s+ error in what they’re reporting at any given moment.

foot pod might work

there's a garmin connect iq third-party app for rolling average pace, which seems to help avoid the jumpiness at the start of a lap that comes with lap pace, as well as the annoying lap alerts.