How random are the generated times?

Each hour, minute, and second value is drawn independently using the Web Crypto API's crypto.getRandomValues(), with rejection sampling to avoid modulo bias, the same cryptographically secure source used for random tokens and keys.

What format are the times in?

Each generated time is formatted as "HH:MM:SS" on a 24-hour clock, one per line, e.g. "14:37:52".

How many times can I generate at once?

Up to 1,000 times in a single batch. Set the count field to however many you need, up to that limit.

How is this different from the random calendar date generator?

This tool generates random times of day, while Generate Random Dates generates random calendar dates. Use them together if you need both a random date and a random time.

Random Clock Time Generator - Generate Random HH:MM:SS Times

Overview

Introduction

Generating realistic random test data for clock-time fields usually means writing a small script, just to get a handful of random HH:MM:SS values.

This tool generates any number of random clock times instantly, each one drawn from a cryptographically secure random source.

What Is Generate Random Clock Times?

A batch random clock-time generator that produces however many HH:MM:SS values you need, each uniformly distributed across the full 24-hour day.

Every hour, minute, and second component is generated independently, so the full range from 00:00:00 to 23:59:59 is equally likely to appear.

How Generate Random Clock Times Works

For each time in the batch, an hour (0-23), minute (0-59), and second (0-59) are each drawn using crypto.getRandomValues() with rejection sampling, which discards out-of-range draws so the result isn't skewed by modulo bias.

The three values are zero-padded and joined into an "HH:MM:SS" string, and all the generated times are listed one per line.

When To Use Generate Random Clock Times

Use it to generate random test data for time-of-day fields, scheduling demos, or randomized sample datasets.

It's also handy for quickly picking a random time for a game, drawing, or icebreaker activity.

Often used alongside Generate Random Dates and Generate Custom Clock Times.

Features

Advantages

Uses cryptographically secure randomness rather than Math.random(), so the output is suitable even for security-adjacent uses like generating unpredictable time slots.
Generates up to 1,000 times in a single batch, with a one-click Regenerate button for a fresh set.
Every output time is a valid 24-hour clock time by construction, no need to validate the results afterward.

Limitations

Generates uniformly random times across the full day; it can't be biased toward a specific time range (like business hours only).
Limited to 1,000 times per batch to keep generation fast and the output manageable.

Examples

Generating a small batch of random times

Input

Count: 3

Output

07:42:19
23:05:56
14:18:03

Each line is an independently generated random HH:MM:SS time; results vary on every regeneration.

Best Practices & Notes

Best Practices

Use the Regenerate button to draw a fresh batch without re-entering the count.
Download the output as a text file if you need to reuse the same batch of random times across multiple test runs.

Developer Notes

The hour, minute, and second for each time are each generated by a local `secureRandomInt(max)` helper that fills a `Uint32Array` via `crypto.getRandomValues()` and rejects draws at or above the largest multiple of `max` that fits in a 32-bit unsigned integer, before taking the result modulo `max`. This rejection-sampling step is what keeps the distribution exactly uniform, a plain `value % max` without it would very slightly favor the smallest values for any `max` that doesn't evenly divide 2^32.

Generate Random Clock Times Use Cases

Generating random time-of-day test data for a scheduling or booking application
Picking a random time slot for a demo, drawing, or icebreaker game
Producing sample data for testing how a UI renders a range of clock times

Common Mistakes

Expecting the same batch to reappear after clicking Regenerate, each click draws an entirely fresh set of random times.
Requesting more than 1,000 times in one batch, which the tool rejects; run it multiple times instead for larger datasets.

Tips

Combine this with Generate Random Dates to build complete random datetime test data.
If you need evenly spaced times instead of random ones, use Generate Custom Clock Times, which builds a deterministic sequence from a start time and step.

Generate Random Clock Times