What step units are supported?

Seconds (s, sec, secs, second, seconds), minutes (m, min, mins, minute, minutes), and hours (h, hr, hrs, hour, hours), all case-insensitive, written as a number followed by the unit, like "90m" or "2h".

What happens when the sequence passes midnight?

It wraps around using modulo arithmetic and keeps counting from 00:00:00, so a sequence starting late at night can produce times that appear to jump backward as it crosses into the next day. No day marker is added, since this tool works on bare clock times, not dates.

What's the maximum count per run?

1000 times. Requesting more is rejected with an error asking for a smaller count.

Can the step move backward in time?

No, only a positive step is accepted; a step of "0" or a negative value is rejected as invalid.

Generate Custom Clock Times | Generate a sequence of clock times from a start time,

Overview

Introduction

Building a list of shift start times, appointment slots, or recurring check-in times by hand is easy to get wrong once the interval doesn't divide evenly into an hour, or the sequence runs past midnight.

This tool generates that list for you: give it a start time, a step, and a count, and it produces every time in the sequence, wrapping cleanly around the 24-hour clock.

What Is Generate Custom Clock Times?

A custom clock time generator that takes a start time in HH:MM, a step expressed as a number and a unit (seconds, minutes, or hours), and a count, then outputs that many HH:MM:SS times, one per line.

Unlike a date generator, it works purely on the clock, so a sequence that runs past midnight simply wraps back to 00:00:00 and continues rather than rolling into a new calendar date.

How Generate Custom Clock Times Works

The start time is parsed as HH:MM and converted to a total number of seconds since midnight; the step is parsed and converted to seconds as well, regardless of which unit you entered it in.

Each time in the sequence is computed by adding a multiple of the step to the start, then applying modulo 86,400 (the number of seconds in a day) so the result always wraps to a valid time of day.

When To Use Generate Custom Clock Times

Use it to build a list of evenly spaced appointment slots, shift start times, or reminder times, like every 90 minutes starting at 9:00.

It's also handy for generating overnight or 24-hour-cycle time sequences where you need to see exactly how the times wrap past midnight.

Often used alongside Generate a Time Sequence, Generate Random Clock Times and Sort Clock Times.

Features

Advantages

Wraps cleanly past midnight using modulo arithmetic, so overnight sequences don't need special-case handling.
Accepts step units in seconds, minutes, or hours, all in one compact input format.
Generates up to 1000 times in a single batch.

Limitations

Caps out at 1000 times per run; larger sequences need to be split across multiple batches.
Works on a bare clock time with no date attached, so it can't tell you which calendar day a wrapped time actually falls on.

Examples

Generating 5 times, 90 minutes apart

Input

09:00
90m
5

Output

09:00:00
10:30:00
12:00:00
13:30:00
15:00:00

Each time is exactly 90 minutes (5400 seconds) after the previous one, computed as seconds since midnight and reformatted.

Generating a sequence that wraps past midnight

Input

23:00
1h
4

Output

23:00:00
00:00:00
01:00:00
02:00:00

After reaching midnight, the running total wraps back to 0 seconds via the modulo operation and continues counting normally.

Best Practices & Notes

Best Practices

Use a step in minutes for appointment or meeting slots, since that's the most common scheduling granularity.
Watch for wraparound when the start time is late in the day; the sequence's early entries may look later than its later entries once it crosses midnight.

Developer Notes

The wraparound uses the double-modulo pattern `((startSeconds + i * stepSeconds) % SECONDS_PER_DAY + SECONDS_PER_DAY) % SECONDS_PER_DAY`, which keeps the result in the 0-86399 range even though none of the inputs here can actually go negative, matching the same normalization pattern used elsewhere in the time category for consistency.

Generate Custom Clock Times Use Cases

Generating a list of appointment or meeting slots at a fixed interval
Building shift start times or check-in reminders spaced evenly apart
Producing overnight time sequences to verify midnight-wrap behavior in downstream code

Common Mistakes

Forgetting that the sequence wraps past midnight rather than continuing to count hours past 23:59:59.
Requesting more than 1000 times in a single run, which is rejected; split large sequences into multiple batches instead.

Tips

If you need actual calendar dates attached to each generated time, pair this tool's output with Custom Calendar Date Generator rather than trying to encode dates into the time step.
Use a small count first to sanity-check the step and start time before generating a full 1000-entry batch.

Generate Custom Clock Times