You Said 30, We Might Plan 24: How Paceriz Calculates Your Weekly Mileage

At onboarding you enter "I run 30 km a week." Many apps just multiply that number and hand you a plan starting at 30. We don't. Paceriz might plan you 24 — because injury risk follows what you actually run, not what you say you run. Here's exactly how we calculate it.

Three inputs: what we use to calculate your mileage

To build a plan, we look at just three things.

1. Your self-reported current weekly mileage. This is the starting anchor — not a target we copy verbatim (more on why below).

2. Your actual training records. Synced from Garmin, Strava, or Apple Health, they tell us two crucial things: your real recent training load, and the longest single run in your history.

3. Your target race — distance and date. This determines which periodization phase you're in, how long the long run should be, and where the time caps sit.

Three inputs, one philosophy running through all of them: what you've actually run recently takes priority over what you say you run.

Why isn't "what you said" what we copy?

Because injury risk follows real load, not self-perception.

Someone who declares "30 km a week" may in fact have only averaged 19 over the last four weeks. If we planned for 30, we'd be pushing their body up 50% in a single week — the most textbook injury scenario there is.

So the weekly target is set like this:

1. The candidate volume is derived from your recent normal runs. A single outlier long run won't raise your starting point — one great day doesn't mean next week should start there.
2. An ACWR guardrail applies. The acute-to-chronic workload ratio: this week's volume can't spike too hard relative to your four-week average.
3. Your self-reported number acts as an anchoring band. The final figure lands between 0.8× and 1.1× of what you declared. Example: you declare 30 but recently ran only 19 — the system gives you neither 19 nor 30. It gives 24 (= 30 × 0.8). The 0.8× floor pulls the candidate up so you don't drop too far, while never charging ahead at 30.
4. Then it progresses weekly, capped at 10% growth per week.
5. A double hard ceiling. One is the time-feasible cap (your runnable days × your per-day time limit); the other is an absolute safety cap. Two walls — whichever stops you first wins.

And if you have no records at all, on your first use? On a cold start we simply trust your self-reported number to begin, flag it as low-confidence, and self-correct week by week as data flows in.

The long run: what low-mileage runners must protect most

When the weekly volume gets compressed, the first thing sacrificed should not be the long run. For anyone training for a race, the long run is a lifeline. So our rule is: we'd rather shorten your easy days than cut the long run.

How is the long-run distance set?

• With records: your longest single run in history × 1.10. The single-session jump guardrail is also capped at 10% — no sudden surges.
• Cold start: in the base phase, weekly volume × 0.35; entering the build / peak phase, it switches to "half-marathon target × 0.8" or "full-marathon target × 0.7."

Then two more ceilings apply, whichever is stricter:

For the marathon, the long run tops out at 80% of race distance — you don't need to run the full 42 km in training to finish it on race day.

How is a week arranged? Runnable days are a ceiling, not a quota

The scheduling order is simple: the long run takes its share first → quality session → easy days split the remainder.

One common misconception to clear up first: ticking "available all 7 days" does not mean we'll fill all 7. Runnable days are our ceiling, not an obligation. We schedule what fits; what doesn't fit, we don't force in.

A recent adjustment (making easy days meaningful): previously, when the remainder was small, the system would carve out "junk-volume" easy days of 2–3 km — runs that feel like nothing yet still eat one of your days. We changed that. Easy days now have a minimum daily volume (≥ 4 km): if there isn't enough to split, we consolidate into fewer days that each feel like a real session. Fewer running days, but every one of them counts.

The kilometres your plan states are the kilometres we scheduled

We specifically fixed this recently, because it comes down to trust.

The kilometres shown in your plan's description are always the actual scheduled volume — never an internal target. When your volume is compressed, we don't hide it; we tell you why:

• "You entered 30, we planned 24" → we explain the recent-real anchoring and the progressive protection. We're not shortchanging you.
• "Target 50, but you only have 4 runnable days" → we explain that the per-day cap can't fit 50, so we show the actual 38 we scheduled rather than dangle a 50 you could never reach.

The number you see is the number you're meant to run. That's our line in the sand.

Know your PB? Enter it at onboarding

If you remember one thing from this article, remember this: if you know your recent personal best (PB), you must enter it at onboarding.

Why does it matter so much? Because mileage decides "how far," but your running fitness (VDOT) decides all of your paces — how fast each segment should be, how slow your easy runs, how quick your intervals, all converted from it. And a PB is the most accurate ruler we have to estimate your fitness.

Without wearable records, we estimate your fitness in this order:

1. Your manually entered PB — the most accurate. With it, your week-one paces line up with you.
2. A conservative prior inferred from your self-reported weekly mileage — this is a recent addition. Previously, no records meant we treated everyone as a beginner with a floor value of 28; now we give a starting point closer to your reported volume.
3. Automatic correction once data syncs in.

See the difference? Without a PB, we can only start from the "conservative estimate" at step 2, and spend the first few weeks correcting toward you. Enter a PB and we start straight from step 1's accuracy.

The bottom line

We believe one thing: a plan you can trust beats a plan with pretty numbers.

That's why we'd rather give you 24 than 30, and rather tell you "it won't fit" than pretend it does. The mileage is computed by an algorithm, held back by guardrails, and what's written is what you're meant to run — so you can train with confidence.

And the single biggest favour you can do your plan is those 30 seconds at onboarding: if you know your PB, enter it. Week one's accuracy starts there.