Data-driven splits for your goal time
Splits are modeled on real swims in our database — not a formula. We find swims for your exact event (distance, stroke, gender and course) and rank them by how close their final time is to your target.
By default we take the 75 closest swims (Top-N). For each split we use the median pace ratio across those swims, then scale it to your target time so the splits add up to it.
As the database grows, Top-N automatically tightens around times like yours, so results stay relevant without retuning.
Under Advanced you can instead use a Window (every swim within ±N seconds of your target) or set a custom Top-N. The long course 400 IM also offers “Swim it like…” presets shaped on a specific swimmer's race.