The Algorithm
How Pacewright makes decisions. Session-load limits, plan adaptation, race predictions, weather adjustments — every formula explained.
13 articles
How Weather Affects Your Pace (And How Pacewright Adjusts for It)
Heat, humidity, and altitude measurably slow you down — and the effect is bigger than most runners expect. Here are the actual numbers, and how Pacewright uses them to keep your targets honest.
Volume Caps: Why Pacewright Will Not Let You Run Too Much
Your weekly mileage, your longest run, and your week-to-week increases all have limits — and those limits change based on where you are. Here's how the guardrails work.
What Counts as a Better Week
Pacewright's engine is an optimizer — it searches for the best training week it can give you. This is the scorecard it uses: what 'better' means, why it's grounded in published science, and why we still show you every piece of it.
How Pacewright Builds Your Training Plan
Pacewright uses published sports science — not a black box — to build your plan. Every decision is based on real research, and we show you exactly why each workout is in your plan.
Missed Workouts: The Safe Reschedule Rules
When you miss a run, Pacewright doesn't guilt you — and it doesn't cram the work into tomorrow. Some workouts get rescheduled, some get dropped, and some are never 'made up.' Here are the actual rules.
Grade-Adjusted Pace: Why Your Hill Run Was Actually Faster Than You Think
Hills make you slower. But they also make you fitter. Grade-adjusted pace tells you what your hilly run would have been on flat ground — and the answer might surprise you.
Race Predictions: How Pacewright Estimates Your Finish Time
Pacewright uses up to three mathematical models to predict your race time — and always gives you a range, not a single number. Here's how each model works and why the range matters.
"Why This Workout Today?"
Every day, Pacewright chooses what you should run. Here's how it works: narrow to what's safe and appropriate, pick the option that scores best for your goal, and show the reasoning.
Why Pacewright Changed Your Workout (And What It Means)
Pacewright doesn't change your workout arbitrarily. Every modification has a specific reason, and the app tells you exactly what it is.
How Pacewright Keeps Your Training Load Safe
The strongest injury signal in runners is a single run that jumps well beyond anything you've done lately. Pacewright guards that first, alongside your weekly volume limits and your own post-run feedback. A separate number, DIAL, tells you whether you're training the right amount — it's a read on your dose, not the thing keeping you safe.
Why Pacewright Shows You Ranges, Not Exact Numbers
Single-number predictions create false confidence. Ranges are honest. Here's why Pacewright always gives you a window rather than a target.
What Pacewright Ignores (On Purpose)
Every feature Pacewright doesn't have is a deliberate decision. Here's what we chose not to build — and why.
Training Load: How Pacewright Measures How Hard You Are Working
Duration times RPE. That's it. No heart rate monitor required, no pace data needed. Here's why this simple formula works, and how it feeds the limits that keep you from doing too much.