Why Your 10.00-Mile Run Becomes 9.99 on Strava
The truth behind that tiny but frustrating difference
It happens all the time—you finish a run, perfectly crafted to 10 miles with Strava Heatmaps, your Garmin watch proudly ticks over to 10.00 miles as expected, but when the activity syncs to Strava, it’s mysteriously trimmed to 9.99.
There is nothing wrong with your watch or your account. This isn’t a bug. In that famous phrase, “It’s a feature,” an intentionally-designed way that Strava handles your workout data.
Strava’s Goal: Precision
Your GPS device and Strava are built for different purposes.
Your watch is a motivator and occasionally errs on the favourable side—it gives you quick, rounded numbers that look clean but still mathematically correct. Strava, by contrast, is the world’s cycling and sports log, a semi-official global data archive for segments, challenges, and personal stats.
That means Strava must treat numbers conservatively. It doesn’t round up or smooth the data—it displays the exact distance your device recorded in the raw activity file.
Why A Garmin Device Might Round Up
Your GPS watch isn’t being dishonest—it’s trying to be helpful
- Rounding for Display: If your device records 9.994 miles, it often rounds that to 10.00 for a nice, tidy number. That is mathematically correct.
- Strava Reads the Raw File: When your activity uploads, Strava receives the true distance (say, 9.993 or 9.999).
- The Result: Because the file never hits exactly 10.000 miles, Strava lists 9.99.
Different brands handle distance slightly differently—some start rounding earlier, and others blend GPS with accelerometer data. Strava acts as a neutral referee, processing all brands’ data with an even hand.
Why Strava Doesn’t Round Up
It’s tempting to think Strava could round up—but that would create new and bigger problems.
- Totals Would Inflate: A hundred runs that each recorded 9.998 miles would display as 10.00, falsely adding extra miles to your yearly total.
- Segments Would Lose Integrity: Strava’s segment leaderboards depend on exact distances. Rounding would skew fair comparisons.
To keep data consistent across millions of athletes and devices, Strava uses one universal rule: show only what’s verifiable.
Strava Tax: The Take Away
TL;DR: Watches can round up, Strava always rounds down.
That 0.01-mile difference isn’t an error—it’s Strava’s enforcing even-handed accuracy measurements. By never ’rounding up’, Strava preserves the integrity of your stats, challenges, and records.
So next time you see 9.99 instead of 10.00, think of it as a slightly harsh maths teacher rather than a Strava Tax. Of course, the solution is to run just that little bit further.
https://the5krunner.com/2025/10/14/strava-vs-garmin-the-climbdown-part-ii/
Last Updated on 30 January 2026 by the5krunner
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors.
Yup, garmin watches do that. On several occasions I noticed that my 9.99 just became 10.00, but some seconds (and paces) passes until auto lap also triggers. Which is a bit funny.
It is just standard (and correct) rounding, depending on the digits available in the respective data field.
I do not think it is right to say that Strava “doesn’t round up or smooth the data—it displays the exact distance your device recorded in the raw activity file.”
What Strava actually does is to _always round down_.
There are some legitimate reasons for being this “conservative” (I think that is a good term) – namely, the athlete really has to achieve the particular result, not just close enough to round up.
However, on average that is actually _less accurate_ and introduces _greater errors_.
maybe.
from a mathematical sense.
but you are right to say that if something is rounded up then it hasn’t been achieved. so in a sports sense its less accurate, depending on the definition
My preference would be to simply “round”. Not Up, or Down. 99.995 goes to 100.00. 99.9949 goes to 99.99. That would be the most accurate for accumulated sums – ie miles ridden during the year.
Rounding 99.9999 to 99.99 is silly for something like this. Just as would be rounding 99.9901 to 100.00.
Are we sure Garmin rounds up rather than just “rounds”.
No, Garmin does not round _up_, rather it simply _rounds_ (the level of significant digits/decimals is just arbitrary and a formatting choice). That was my exact point: Simple rounding reduces the expected “inaccuracy” for any given activity (and over the time reduces the _actual_ cumulative inaccuracy) – but as T5KR points out, introduces the potential for “false achievements”.