Redstone clocks explained: repeater, hopper, and comparator clocks in Minecraft 26.2

A redstone clock is any circuit that switches itself on and off, over and over, without you touching it. That single idea powers an enormous amount of Minecraft: auto-farms that harvest on a timer, mob switches that pulse, hidden doors that reset, and any contraption that needs a steady heartbeat.

The problem is that "redstone clock" is not one thing. There are several designs, they run at wildly different speeds, and some of them will quietly wreck your server's tick rate if you use them wrong. This guide covers the three clocks worth knowing, when to reach for each, and the one mistake that turns a clock into a lag machine.

Everything here is pinned to Minecraft 26.2 Java Edition, where clock behavior is stable. Clocks are built entirely from the repeater and comparator, so if the terms "tick," "delay," or "signal strength" are fuzzy, read those first. For the full component map, keep the redstone handbook handy.

What "clock speed" actually means

Every clock has a period: the time for one full on-then-off cycle. Redstone timing is measured in redstone ticks, and one redstone tick is 0.1 seconds. So a clock with a period of 20 redstone ticks fires once every 2 seconds.

Two facts shape every clock you build:

• Faster is not better. A clock that pulses every tick updates constantly, and dozens of them across a base add up to real server load. Most farms want the slowest clock that still keeps up.
• The signal needs to travel. A clock is only useful if its pulse reaches the machine it drives. Long lines need repeaters to survive the trip.

The repeater clock: simple and adjustable

The repeater clock is the one most players build first, and for good reason. It is a small loop of redstone that feeds back into itself through repeaters, and the repeater delays set the speed.

How it works: a redstone line loops back on itself so its own output re-triggers its input. Insert repeaters into the loop, and their combined delay sets the period. Add a torch or a lever tap to start it, and it pulses forever.

• Strengths: dead simple, and the speed is tunable, just right-click the repeaters to change delay.
• Weaknesses: hard to make slow. To get a multi-second period you need a long chain of repeaters, which eats space fast.
• Best for: short, fast pulses where you want easy speed control, like a rapid dispenser or a test rig.

The hopper clock: slow, compact, and reliable

When you need a slow clock, seconds or minutes per pulse, the hopper clock is the classic answer. It stores its timing in items instead of wire, so a long period stays physically small.

How it works: two hoppers face into each other, and a handful of items bounce back and forth between them. A comparator reads each hopper, and when the items finish moving to one side, the comparator flips the output. The pulse length is set by how many items you load in.

• Strengths: extremely compact for long delays, and rock-solid reliable. Two hoppers can hold a period of many minutes.
• Weaknesses: not instantly adjustable, you change the timing by adding or removing items, and it takes a moment to settle.
• Best for: auto-farms and mob switches that fire on a long, steady interval. This is the workhorse clock for most survival bases.

Because each item takes a fixed time to transfer, you can dial in almost any period just by counting items. Two hoppers with a few stacks between them can run a farm that harvests once a minute, all in a two-block footprint.

The comparator clock: the steady middle ground

The comparator clock uses a comparator's ability to read a decaying signal, producing a clean, repeating pulse without a huge repeater chain. It sits between the repeater clock's speed and the hopper clock's slow reliability.

How it works: a comparator feeds a subtracting loop so the signal builds and drains on a fixed cycle, producing a regular pulse. Adjusting the loop length changes the period.

• Strengths: compact, produces a clean pulse, and handles medium speeds well.
• Weaknesses: less intuitive to tune than a repeater clock, and easy to wire backward if you are new to subtract mode.
• Best for: medium-interval tasks where a repeater chain would be too bulky but a hopper clock too slow.

Think of the three clocks as a speed ladder: repeater for fast, comparator for medium, hopper for slow. Almost every timing job in survival is solved by picking the right rung, not by inventing a new circuit.

Which clock should you use?

Clock	Typical period	Footprint	Best use
Repeater	Sub-second to ~2s	Grows with delay	Fast pulses, test rigs
Comparator	~1s to ~10s	Compact	Medium-interval machines
Hopper	Seconds to minutes	Tiny for long delays	Farms, mob switches

If you take one rule away: use the slowest clock that still does the job. A crop farm that only needs to fire once a minute should never be driven by a fast repeater loop. The slower clock is smaller, lags less, and is easier to keep in one loaded chunk.

Turning a clock into a machine

A clock on its own just blinks. It becomes useful when its pulse drives something: a dispenser, a piston, a note block, or the harvesting mechanism of a farm. The pattern is always the same, clock produces a steady pulse, repeaters carry it to the machine, and the machine does its job on every beat.

Once you are comfortable with clocks, the next step is timed piston work, where the delay between two pulses decides whether a door opens cleanly or jams. That timing is covered in the piston doors guide, and the broader theory lives in the redstone handbook. A clock is simply a repeater delay that never stops, so the more comfortable you are with repeater timing, the more control you have over every machine you build.

Frequently asked questions

What is the simplest redstone clock?

A repeater clock: a small redstone loop that feeds back into itself through one or more repeaters. The repeater delays set the speed, and right-clicking them tunes it. It is the easiest clock to build but hard to make slow.

How do I make a slow redstone clock?

Use a hopper clock. Two hoppers face into each other with a handful of items bouncing between them, and a comparator reads when the items finish moving. The number of items sets the period, so two hoppers can hold a delay of many minutes in a tiny space.

Do redstone clocks cause lag?

Fast clocks can. A clock that fires every game tick floods the redstone update queue and can drag down a chunk's tick rate. Always use the slowest clock that still does the job, most farms only need a pulse every several seconds.

Why did my redstone clock stop when I walked away?

The chunk unloaded. A clock only ticks while its chunk is loaded, so a farm stops running once you leave its area. Keep timed farms near spawn chunks or inside your simulation distance.