Free from Swimio

Professional swimming tools, free in your browser.

Plan a race, find threshold pace, coordinate send-offs, or time the whole pool deck. Every tool works immediately without an account.

Choose the job on deck.

Each tool does one job. Test your threshold, turn it into splits, then time the set on deck.

  1. 01

    Swim Pace Calculator

    Create exact pool or open-water pace plans, variable pacing curves, cumulative splits, and send-offs.

    Plan a swim
  2. 02

    Critical Swim Speed Calculator

    Turn 400 and 200 test times into CSS pace, practical training ranges, and projected swim times.

    Calculate CSS
  3. 03

    Swimming Pace Clock

    Run a four-hand pool pace clock with wall time, synchronized sessions, send-off intervals, sound, and visible mode.

    Open pace clock
  4. 04

    Swim Stopwatch

    Run a professional single stopwatch with lap history, target split progress, and live pace analysis.

    Open stopwatch

01 · Test

Find the honest baseline.

Use race times or a 400/200 CSS test to establish pace from real swimming.

Follow the CSS test protocol

02 · Plan

Turn pace into exact splits.

Model even, positive, or negative pacing and carry the targets into the pool.

Build the pace plan

03 · Time

Keep the session moving.

Use a shared pace clock or the stopwatch mode that matches the swimmers on deck.

Learn pace-clock send-offs