> ## Documentation Index
> Fetch the complete documentation index at: https://rendzo.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Time

> Add or modify timestamps and speed data in your routes

The Time tool allows you to add timestamps to tracks that don't have them, or modify existing time data based on speed and distance calculations.

## Overview

This tool is useful for:

* Adding timestamps to manually created routes
* Adjusting time data for planning purposes
* Correcting inaccurate timestamps from GPS recordings
* Calculating expected arrival times based on your pace

## How Fields Are Linked

The Time tool maintains relationships between speed, time, and distance:

### Speed and Moving Time

**Speed** and **Moving Time** are linked by the track's distance:

* Change speed → recalculates moving time (distance ÷ speed)
* Change moving time → recalculates speed (distance ÷ time)

### Start and End Times

**Start** and **End** times are calculated from moving time:

* Change start → recalculates end (start + moving time × ratio)
* Change end → recalculates start (end - moving time × ratio)

The "ratio" accounts for stopped time, calculated as (total time ÷ moving time).

## Creating Timestamps from Scratch

For tracks without existing time data:

1. Set your expected **speed** (e.g., 15 km/h for cycling)
2. The tool calculates **moving time** based on your track distance
3. Pick a **start date** - time defaults to noon
4. The **end date/time** is calculated automatically

## Editing Existing Timestamps

For tracks with existing time data:

* **Change start** → If end exists, recalculates speed and moving time from the time span
* **Change end** → Recalculates speed and moving time from the time span
* **Change speed** → Recalculates moving time, updates end time
* **Change moving time** → Recalculates speed, updates end time

## The Reset Button

The **X** button resets all fields to the current values from your GPX file. Use this to undo your edits and reload the original data.

## Applying Changes

Click **Update Time Data** to write your changes to the GPX file.

<Note>
  When modifying existing timestamps, changing the time or speed will shift, stretch, or compress the timestamps proportionally along the entire track.
</Note>