Which Clocks Are Considered The Most Accurate?

Atomic Clocks are considered the most accurate clocks that we have right now. These clocks are super accurate and are the reason our world can function the way that it does. Believe it or not, it is the reason that we are able to use the internet the way that we do and even the GPS systems.

Atomic clocks are clocks that measure the oscillations (movement) of atoms. This is pretty complicated stuff but the basic concept is that all atoms of a given element vibrate or tick the same number of times per second. To elaborate, there are 9,192,631,770 ticks in one second. And though this number seems a bit weird it is quite important. Since today the international standard for what a second is based on that many vibrations/ticks of a cesium atom

Fun fact:

The clock that the U.S. uses to calibrate its time is accurate to a second in a 100 million years. So if you had put one of these clocks in the medieval ages they will still tell the same time in this day and age.

Data transmission on the internet, as well as the GPS navigational system and cell phone towers and even the high grid, depends on this clock. In conclusion, our high-speed interconnected world works because we can use different pieces of technology using accurate time. So, you take that out of the way, and say good buy to the internet? And isn’t that just sad?

Moreover, whenever we build a new clock, engineers find a good way to use it. So, in the future, if we develop even more accurate clocks, who knows where they will lead us. Now that we have cleared some dust off atomic clocks, let’s take a look into some of the other clock types and their accuracy. And if you want to take a deeper look into Atomic clocks, NASA has a great article written on just that so do give it a look too if you are interested, “What Is an Atomic Clock?

Mechanical Clocks

Mechanical clocks were considered one of the most accurate clocks when they were invented, but not so much nowadays. So how does a mechanical clock work? Basically, mechanical clocks make use of gears in order to tell the time. They have two main components, a mainspring and a pendulum. These type of clocks require winding with an object like a key, this tightens the mainspring. As the mainspring unwinds, the stored energy is transferred to gears which are used to tell time.

The pendulum, on the other hand, helps keep the time in sync as it moves second by second. Some types of mechanical clocks also use weights instead of the mainspring in order to pull the gears at the right pace. An advantage of a mechanical clock is the fact that it does not require electrical energy to function when a whole cycle of winding is finished, mechanical clocks need to be wound once more. Due to the high mechanical nature of these type of clocks, they are very less accurate as the clock has to be wound physically.

pendulum clock

Pendulum Clocks

There’s no argument about the fact that these clocks are a great sight to see, but what about their accuracy? There are different types of Pendulum Clocks and some clocks only use Pendulums just for the look of it. We will look over the clocks which purely function on the energy transfer which is done by the pendulum itself.

So how does a pendulum clock work and how accurate is it? The pendulum clocks are quite similar to the mechanical clocks when it comes to their functionality. In fact, the only difference is perhaps the fact that pendulum clocks use potential energy for providing energy to the system while mechanical clocks use spring energy.

Click Here To Learn About The 10 Best Pendulum Clocks

How does a pendulum clock work?

Essentially, a pendulum clock uses dial and hands to show time, a weight for potential energy, set of power gears, set of timekeeping gears, a pendulum and an escapement. A weight is used to store potential energy which is then transferred to the clock mechanism. It also requires winding the weight back for more potential energy to be stored. Power gears are used to convert the energy provided by the weight and use it for clock mechanism, the heavier the weight the more energy will be stored and the clock will function for more time without requiring it to be wound. Timekeeping gears are used to drive the different hands of the clock for showing proper time. Finally, the pendulum and escapement are used for regulation and proper syncing of time with the rest of the system.

How Accurate is a Pendulum Clock?

Now let’s move on to the accuracy of the clock? This clock like the earlier mechanical clocks is not very accurate, mainly due to three reasons, firstly it’s highly mechanical and needs manual winding. Secondly, the expansive and contractive property of metal also contributes to its inaccuracy, you see pendulums are only accurate if they use the same length, due to the contraction or expansion of metal, the pendulum length will change and it will measure different time. Lastly, the gravitational force acting on Earth which varies from place to place. It is strongest near the centre and weakest at the edges. Due to this if the same pendulum clock is used to measure time near a pole and near the centre, times it measures will be different.

quartz clock,Which Clocks Are Considered The Most Accurate_

Quartz Clocks

Quartz clocks are by far the most widely available clocks nowadays and they are decently accurate.

How does a quartz clock work?

Quartz clocks were invented when it was discovered that Quartz had piezoelectric properties, which means if it is squeezed it will produce a small voltage and it goes the other way around, meaning if a voltage is passed through a quartz clock, it will vibrate. Essentially, quartz clocks are battery powered but they use very little electricity. In most cases, the batteries will run a couple of years before giving up. The battery provides voltage to the circuit which then transfers this voltage to the crystal and makes it vibrate. The circuit then converts the vibration signals into electric pulses. These electric pulses are used to drive the electric stepping motor which in turn moves the clock hands.

How accurate is a quartz clock?

It’s pretty accurate for day to day use, but it does lose some accuracy over time. This happens because quartz vibrates at a slightly different frequency over different temperatures and pressures, due to this over time it decreases in accuracy little by little. But overall it’s one of the most accurate types of clock commercially available.

atomic clock, Which Clocks Are Considered The Most Accurate_

Atomic Clocks

Atomic clocks are by far the most accurate in timekeeping. Let us look at how accurate they are and how they function.

How does an atomic clock work?

Atomic clocks use natural oscillation of atoms in place of a pendulum, but they are far more accurate than any other conventional clock. The reason behind this is that atomic oscillations have a much higher frequency and are much stable than for example a pendulum. Atomic clocks work on the following basic principle.

  • Atoms are heated and joined together to form a beam.
  • Only a single state of an atom is passed through a resonator.
  • Resonator changes some of the atoms to another state.
  • A detector counts how many atoms changed their state.
  • This helps to tune the microwave frequency to the oscillation of atoms.
  • When it is properly tuned then the time is measured.

How accurate is an atomic clock?

It is the most accurate clock currently available. So accurate that it takes about a million years for the clock to loose one second.


To sume things up once again, Atomic clocks are without a doubt the most accurate clocks that we have, followed by quartz clocks ( which are the clocks that we conventionally use in our homes like Analog and digital clocks ). And then come mechanical clocks.

AK Iqbal

A University of London’ student with a passion for writing. Clocks have always intrigued me and the importance that they have in our lives is way beyond phenomenal. So, on this site, I write everything about clocks, everything from answering any clock-related queries that you might have along with recommending some of my favorite clocks accordingly. Moreover, I will also be conducting some researches on clock related topics and sharing the things that I learn. So stay tuned to ohmyclock for all the fun clocks related content

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