# Custom zones for sports

**URL:** <https://forum.intervals.icu/t/custom-zones-for-sports/114875>\
**Category:** Announcements\
**Created:** [3 November 2025 11:55 UTC](https://forum.intervals.icu/t/custom-zones-for-sports/114875 "2025-11-03T11:55:19Z")\
**Posts on this page:** 1\
**Showing post:** 53

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**Author:** ![Pierre\_du\_Pont](https://forum.intervals.icu/letter_avatar_proxy/v4/letter/p/9fc29f/32.png) [@Pierre\_du\_Pont](https://forum.intervals.icu/u/Pierre_du_Pont)\
**Post date:** [25 March 2026 18:22 UTC](https://forum.intervals.icu/t/custom-zones-for-sports/114875/53 "2026-03-25T18:22:47Z")

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> [@claybeans](#):
>
> The only solution I could think of is creating one zone for each percentage (1005KRP = 100%, 995KRP = 99%, …, 15KRP = 1%). But I’m also running into the issue that pace percentages are calculated differently on intervals than the [Running Writings calculator](https://apps.runningwritings.com/pace-percent/), so I didn’t implement it. I suspect that intervals is using the speed to calculate the percentage instead of time (as mentioned on the calculator page), but I have no idea.

@brainiak005  
@claybeans

Hey, sorry to necro a dead thread, but I actually set up some custom zones for 5K and Marathon pace based on the Running Writings calc. You have to do some math to get the percentages correct, since as you point out the pace percentages are calculated differently, but I did it.

The two zone sets are “Marathon Pace Zones” and “5K Pace Zones”, and they depend on two fields, “Marathon Pace” and “5K Pace”. These are public – if you search for them, you should find them

I added most of the breakdowns he uses, as well as a couple of others. For marathon pace, I had to get more nitty gritty, since he uses 90, 92, 94, 95, and 96, so the ranges get a little tight in that area.

In general, I would either do the lower bound to upper bound (e.g. Easy is 65%-75%) or a little around each, (e.g., 95% is actually 94.5% to 95.5%, and 96% is actually 95.5% to 96.5%, I think)

EDIT: A little more detail about the math/calculations in this thread, if you want to reverse engineer exactly where the cutoffs are: [Custom zones work started - #115 by Pierre\_du\_Pont](https://forum.intervals.icu/t/custom-zones-work-started/112132/115)

 ![image](https://forum.intervals.icu/uploads/default/original/3X/7/b/7be0ec71f3cebf0ee5fcc335ad4cf0f056360c7e.png)

 ![image](https://forum.intervals.icu/uploads/default/original/3X/7/2/7243513eb719266932a69db02d272a7ad97673f3.png)

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