Redstone Clocks and Timers Explained

A clock is a redstone circuit that turns itself on and off forever. Almost every automatic farm needs one somewhere, and picking the right type is the difference between a contraption that runs smoothly and one that lags your world.

Redstone timing basics

Everything is measured in redstone ticks. One redstone tick is 0.1 seconds; one game tick is 0.05 seconds, so a redstone tick is two game ticks.

A repeater has four settings, adding 1 to 4 redstone ticks of delay each. This is your main tuning tool — chain repeaters to build up longer delays.

The repeater clock — simple and fast

The classic. A loop of redstone dust and repeaters feeding back into itself.

• How to build it: a ring of repeaters and dust where the output feeds the input. Break the loop with a lever or a redstone torch so you can switch it off.
• Timing: set by the total repeater delay around the loop. Add repeaters or increase their settings to slow it down.
• Good for: short, fast cycles where you want precise control.
• Watch out for: it is easy to make it too fast. A very fast repeater clock driving pistons will cause noticeable lag, and can break some contraptions outright.

Always include an off switch. A clock you cannot stop is a clock that runs while you are away doing something else.

The hopper clock — the workhorse

Two hoppers facing into each other, with items passing back and forth, and comparators reading the contents.

• How it works: items shuttle between the two hoppers. A comparator reads how full a hopper is and outputs a signal when the items arrive. The cycle length depends on how many items you put in.
• Timing: add items to slow it down, remove them to speed it up. Extremely easy to tune — and it comfortably reaches multi-minute intervals, which repeater clocks cannot do practically.
• Good for: almost every automatic farm. Crop farms, smelters, anything on a slow cycle.
• Why it wins: it is cheap, compact, easy to adjust, and gentle on performance.

This is the default choice for most builds, and if you learn only one clock, learn this one.

The comparator clock — compact

A comparator in subtraction mode feeding back into itself through a repeater produces a very fast oscillation.

• Good for: tight spaces where you need a fast pulse and have little room.
• Watch out for: it is genuinely fast, and that makes it a common lag source. It is also harder to tune than a hopper clock.

The observer clock — smallest and fastest

Two observers facing each other. Each detects the other's state change and fires, producing a continuous, very fast pulse in a two-block footprint.

• Good for: situations demanding maximum speed in minimum space.
• Watch out for: it is the fastest of the four and correspondingly the most demanding. Use it deliberately, not by default.

Observers are also useful outside clocks entirely — they detect block changes, so they can trigger on a crop growing or a piston moving, which is often better than running a clock at all.

Choosing the right one

• Slow cycle, a farm, minutes between pulses — hopper clock.
• Precise short delay, a few ticks — repeater clock.
• Tight space, fast pulse — comparator or observer clock.
• You only need to react to something happening — do not use a clock at all. Use an observer or a pressure plate.

That last point is the one experienced builders lean on: an event-driven circuit that fires when something actually changes is almost always better than a clock polling constantly. A crop farm triggered by an observer watching a crop is more efficient than one on a timer, because it does nothing when nothing has happened.

Building an off switch

Every clock should have one. The simplest approach is a lever feeding a redstone torch that blocks the loop, or a lever cutting the dust line directly. For hopper clocks, a hopper with a comparator lock or simply removing the items works.

Without a switch, the clock runs whenever the chunk is loaded, which means it is consuming resources and possibly triggering dispensers while you are on the other side of the world.

Where clocks fit into farms

Most of the farms covered on this site use one somewhere: the automatic crop farm runs on a slow cycle, and a hopper clock is the natural fit. If you are new to redstone components generally, our redstone basics guide covers signal strength, repeaters and comparators from the beginning.

And if a contraption needs sticky pistons — most moving builds do — you will need slimeballs. Our slime chunk guide covers farming them reliably, including finding your chunks on the seed map.