Swimming Pace and Interval Builder

Convert swim benchmark times into 25m, 50m, and 100m pacing and generate CSS-style threshold intervals

Turns a swim benchmark into split targets and send-off based interval sets so athletes and coaches can build threshold-oriented pool sessions quickly.

Example Results

1 examples

Build a CSS threshold set from a 1:30 per 100m swimmer

Convert a 90 second 100m benchmark into 25m and 50m splits, then generate a 10x100 set with 15 seconds rest.

{
  "paces": {
    "pacePer25mSeconds": 22.5
  },
  "intervalSet": {
    "sendOffSeconds": 105
  }
}
View input parameters
{ "benchmarkDistanceMeters": 100, "benchmarkTimeSeconds": 90, "poolLengthMeters": 25, "repeats": 10, "intervalDistanceMeters": 100, "restSeconds": 15 }

Key Facts

Category
Health, Sports & Fitness
Input Types
number
Output Type
json
Sample Coverage
4
API Ready
Yes

Overview

The Swimming Pace and Interval Builder converts benchmark swim times into precise pacing targets for 25m, 50m, and 100m distances, generating Critical Swim Speed (CSS) threshold interval sets with custom send-off times.

When to Use

  • •When planning structured pool workouts based on a recent time trial or benchmark swim.
  • •When calculating exact target splits for 25m, 50m, or 100m intervals to maintain a consistent threshold pace.
  • •When designing send-off times for swim squads or individual training sessions to ensure proper rest ratios.

How It Works

  • •Enter your benchmark swim distance and the time it took to complete it.
  • •Specify your pool length along with your desired interval distance, repeat count, and rest period.
  • •The tool calculates your target split paces and generates a structured interval set with calculated send-off times.

Use Cases

Coaches generating customized send-off times for swim squad lane groups based on varying fitness levels.
Triathletes calculating precise 100m pacing targets for CSS threshold sets in a 25-meter pool.
Fitness swimmers structuring a 10x100m interval workout with consistent rest periods.

Examples

1. Calculating CSS Intervals for a 400m Time Trial

Triathlon Coach
Background
A coach needs to set up a threshold set of 10x100m for an athlete who recently completed a 400m benchmark swim in 6 minutes (360 seconds).
Problem
Manually calculating the 100m threshold pace and adding a 15-second rest to find the exact send-off time.
How to Use
Set the benchmark distance to 400m, benchmark time to 360 seconds, pool length to 25m, interval distance to 100m, repeats to 10, and rest to 15 seconds.
Example Config
{
  "benchmarkDistanceMeters": 400,
  "benchmarkTimeSeconds": 360,
  "poolLengthMeters": 25,
  "repeats": 10,
  "intervalDistanceMeters": 100,
  "restSeconds": 15
}
Outcome
Generates a target pace of 22.5 seconds per 25m and a send-off time of 105 seconds (1:45) per 100m interval.

2. Pacing 50m Repeats in a Long Course Pool

Master Swimmer
Background
A swimmer wants to run a high-intensity threshold set of 20x50m in a 50m Olympic-sized pool based on their 100m benchmark of 80 seconds.
Problem
Determining the correct pace splits and send-off times for a 50m pool with 10 seconds of rest.
How to Use
Input a 100m benchmark distance, 80 seconds benchmark time, 50m pool length, 20 repeats of 50m intervals, and 10 seconds of rest.
Example Config
{
  "benchmarkDistanceMeters": 100,
  "benchmarkTimeSeconds": 80,
  "poolLengthMeters": 50,
  "repeats": 20,
  "intervalDistanceMeters": 50,
  "restSeconds": 10
}
Outcome
Calculates a 50m split pace of 40 seconds and sets a send-off interval of 50 seconds per repeat.

Try with Samples

health
Copyright-Free AAC Audio Samples
High-quality AAC encoded audio samples for testing and development, featuring nature sounds and meditation music with excellent compression
keywords and
sample
Camera RAW Photo File Samples
Downloadable sample files covering Sony ARW/SRF/SR2, Canon CR2/CR3/CRW, Adobe DNG, Nikon NEF/NRW, Fuji RAF, Olympus ORF, Panasonic RW2, Leica RAW/DNG, and a generic RAW binary file for testing camera RAW upload workflows.
keywords and
sample
Contentful Cloud-based CMS Samples
Comprehensive Contentful examples covering content modeling, API integration, webhooks, migrations, and frontend integration patterns
keywords and
sample
BDD with Cucumber - Behavior Driven Development
Comprehensive Cucumber BDD examples including feature files, step definitions, data tables, hooks, and advanced BDD patterns for collaborative development
keywords and
sample

Related Hubs

Health Tools
Explore 29 health tools for utility workflows and compare closely related utilities quickly.
Meditation, Sleep, and Relaxation Tools
Compare guided meditation, breathing routines, PMR, sleep-cycle planning, stress self-checks, and supporting audio tools in one hub for calmer daily routines.
Endurance Training Pace, Heart Rate, and Effort Tools
Compare pace calculators, heart-rate zone tools, VO2 max estimates, cycling power, calorie burn, and training-load metrics in one hub for running, cycling, swimming, and triathlon planning.
Audio Encoding and Format Conversion Tools
Compare audio format conversion, bitrate changes, sample-rate conversion, codec swaps, and export tools in one hub for delivery and archive workflows.

FAQ

What is a CSS-style threshold interval?

It is a training pace designed to match your Critical Swim Speed, helping improve aerobic capacity by using structured send-off times.

How does the tool calculate the send-off time?

It adds your target interval pace to your desired rest time, rounding to a practical send-off interval.

Can I use this for both 25m and 50m pools?

Yes, you can set the pool length option to either 25 or 50 meters to match your training facility.

What benchmark distance should I use?

Typically, a 100m or 400m time trial benchmark is used to establish baseline threshold paces.

What does the output JSON contain?

It provides calculated split paces (such as pace per 25m) and the final send-off time in seconds for your interval set.

API Documentation

Request Endpoint

POST /en/api/tools/swimming-pace-interval-builder

Request Parameters

Parameter Name Type Required Description
benchmarkDistanceMeters number Yes -
benchmarkTimeSeconds number Yes -
poolLengthMeters number Yes -
repeats number No -
intervalDistanceMeters number No -
restSeconds number No -

Response Format

{
  "key": {...},
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}
JSON Data: JSON Data

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-swimming-pace-interval-builder": {
      "name": "swimming-pace-interval-builder",
      "description": "Convert swim benchmark times into 25m, 50m, and 100m pacing and generate CSS-style threshold intervals",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=swimming-pace-interval-builder",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]