What this result means
A progression run is not a two-phase negative split. Pace changes every kilometre or mile, linearly from the first interval to the last. You set how much faster the last interval is than the first (default 5%). The tool then scales every step so the finish matches the goal time.
Negative splits change once, at halfway. Progressive changes on every marker. Easy-to-fast long runs and some 10K tactics look like this more than a single half-and-half cut.
A 10 km in 50:00 with 5% progression has a first kilometre slower than 5:00 and a last kilometre faster than 5:00. Average pace is still 5:00/km. A 0% progression is even splits.
A 16 km long run in 1:20:00 with 8% progression starts like easy running and finishes nearer tempo. That is a workout shape, not a race predictor.
Calculation method
Each interval gets a relative weight that interpolates from 1 down to (1 − percent). Interval time is proportional to distance times weight. Times are scaled so they sum to the goal. Displayed paces round to the nearest second.
Exact arithmetic on that profile. It does not know warmup, cooldowns, or rest.
Large percentages on short intervals demand a very fast last rep. If the last kilometre is faster than you can hold, reduce the percent or slow the goal.
Frequently asked questions
How is progressive pace different from a negative split?
Negative splits use two paces, switching at halfway. Progressive interpolates pace across every kilometre or mile.
Does the average still match my goal?
Yes. The finish time is the time you entered. Early intervals are slower, late ones faster, and they sum to the goal.
What percent should I use?
3–8% is a usable workout range. 5% is the default. Race-day progression is often gentler than a training progression run.