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Unless you are familiar with the food storage industry, chances are that you won’t know how to read Julian dates.

These are the numerous numbers displayed on #10 cans and MREs, and the expiration date code converter for survival food.

Often, the aforementioned numbers illustrate the manufacturer’s Julian dates.

Let’s learn more about the Julian date. 

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What’s Julian Date and Time?

The Julian day, also known as Julian day number, is the number of days that have elapsed since the first epoch known as noon Universal Time, which fell on the 1st of January 4713 BC in the Julian calendar.

The Julian date can be described as a continual count of fractions and days that have advanced since the inaugural epoch. 

Where did Julian Dates Originate from?

Nearly 2.5 million days have passed since the inaugural Julian date calendar.

It’s worth noting that Julian dates are used widely as time differences in astronomical software.

In October 1582, the Julian calendar transitioned to the Gregorian calendar, according to the system established by Pope Gregory the XIII. 

How do You Read Julian Code?

A Julian code is just but a number.

A Julian date is a four or five-digit number that starts with the last 2 digits which often illustrate the year when the item was produced.

The final three numbers correspond with the year the item was made too. 

Why use Julian Dates?

The time scale that’s used to determine the Julian time is universal, meaning that it’s used across the world.

The reason why the Julian time is often used in MREs (Meals Ready to Eat) is that they emanated from the military. 

The procurement structures within the military utilize the Julian date code in their computer programs as a clear standard that doesn’t need letters, one that acknowledges the incorporation and use of date calculations without the need for additional supporting programs. 

Often, manufacturers utilize Julian date format because that’s the common practice in the industry.

As consumers today become more knowledgeable, many manufacturers are adopting a readable and clearer date of manufacture. 

Explanation Video

Which is the best way to Calculate the Julian Date?

There are a couple of ways to do this.

First, to find out the Julian calendar today, calculate the number of years there are between 4713 BCE and the current year. 

Or, you can also use this method.

To determine the Julian date, all you need to do is multiply the number of leap years by 366 and the number of non-leap years by 365. Add the totals you get together to get the cumulative number of days in all the years.

Take away 10 days to cater to the transition in the calendar system from Julian to Gregorian. 

Convert Julian Dates (Video)

Helpful Example

For instance, the year is currently 2019. If you calculate 4713 BCE (Before Common Era) and 0 CE (Common Era) you get 4713.

Now, from 0 CE to 2019 you get 2019 years. Remember, 0 CE is one year.

Common Era (CE) is comparable to AD.

Cumulatively, the total number of years you’ll get is 6732. You’ll now need to calculate the number of the years in between this period that was a leap.

One thing you’ll need to consider here is that every fourth year that fell before 1582 was a leap year. 

After 1582, not every fourth year that happened in between century changes was termed as a leap year.

This would only happen when the years were a four hundredth year.

For instance; while 1600 and 2000 were leap years, 1700, 1800, and 1900 weren’t.

Proceed to find the total number of non-leap years and multiply your result by 365. Multiply the number of leap years by 366. 

Get your cumulative result by adding your totals together.

The result you get illustrates the number of days in all the years. Now subtract 10 days to cater to the transition in the calendar system from Julian to Gregorian that happened in the year 1582.

Calculate the number of days there are between January 1 the current date of the current year. 

For instance, assuming the date you’re converting is the 28th of February, consider that there are 59 days between the 1st of January and the 28th of February.

Add your answer to the total number of days. Include an extra day for leap years in February. That is instead of 28 days in February, make it 29 days. 

Calculating the Number of Seconds 

If you need to calculate the number of seconds in a Julian date calendar, you need to analyze seconds starting at noon.

Assuming your current time falls between noon and midnight, you’ll be looking for the number of seconds since noon the previous day. 

For instance, assuming your current time is 6:25:15 PM, you’ll establish that 23, 1115 seconds have passed since the afternoon.

If your current time is 6:25:15 AM, on the other hand, an additional 43,200 seconds will have passed between noon the previous day and midnight and the total will be 66,315 seconds. 

Proceed to split up the total number of seconds by 86,400, which is the cumulative number of seconds in an entire day.

For instance, in our first example of 6:25:15 PM, you’ll need to divide 23,115 by 86,400 to get a day fraction of 0.2675. For 6:25:15 AM, you’ll need to divide 66,315 by 86,400 to get 0.7675.

Include your answer to your daily total to get your entirely converted Julian date.  

How to Read a Julian Date on Packaged Food 

You can easily read the Julian date on packaged food by; finding the three to a seven-digit number inscribed on your food.

Often, packaged food substances come fully stamped with Julian dates on them which illustrate the packing date.

These dates are usually between 3 to 7 digits long and are counted differently from the Julian calendar 2018 used in astronomy. 

Where are These Numbers Located? 

Common areas where you can find these numbers include; the bottom side of cans (like #10 cans) and on the sides of cartons.

Helpful reading: #10 Can: What Is It (Sizes, Equivalents, & Shelf Life)

If your packaged food comes with a best by date, check to ensure that it’s been illustrated in an ordinary calendar format, instead of the Julian date 2019.

This saves you from the hassle involved in trying to convert the Julian date.

Locate the year by checking the inaugural 2 digits in cases where the number is 5 digits long.

For instance, if you’re having a 5 digit number and the inaugural two digits are 17, this shows that it correlates with 2016.

If you notice a 3 digit long number displayed on a perishable product, chances are that it was packaged in the current year.

You can establish the year from the inaugural 4 digits in cases where the number includes 7 digits.

Some of today’s Julian date will display the entire year in 4 digits which are incorporated for clarity purposes. 

When it’s a 7 Digit Number

For instance, assuming it’s a 7 digit number and the inaugural 4 digits are 1998, this will correlate with the year 1998.

Proceed to change the last 3 digits to the current calendar date.

It’s worth noting that the last 3 digits indicate the packaging day, calculating up from January 1, as 001. These illustrate the successive days of the year. 

You can change to the Gregorian calendar with the help of a chart. However, you‘ll need to consider whether you’re in the leap year or not.

In this case, assuming the Julian date calendar 2017 was 17234, this corresponds with the year 2017 and this isn’t a leap year. 234 on the other hand, correlate to the 22nd of August 2017.

Assuming the Julian calendar 2017 was 2000107, the year would be 2000 which in this case is a leap year.

The date, therefore, would be the 16th of April 2000.  

What is the Julian Date Today?

Let’s take an example using the 26th of November 2019. That would mean the current Julian date is 19330. 

Where’s Julian Date on Eggs?

Many of the eggs you’ll find in stores are brought there a few days after they have been laid. Establishing how fresh eggs can be an arduous task. Often, the Julian date of eggs is the pack date, that is the date when the eggs were cleaned, graded, and arranged in the carton. Often, the Julian date is located at the short side of the carton. Remember, eggs are safe for consumption between a period of four to five weeks. They can still be consumed beyond that time but you’ll need to refrigerate them.

How do You Convert Julian Date? 

Fortunately, converting the Julian date is becoming easier by the day. Today, you can leverage the many date code converters available online to make the process easier and faster. 


The Julian date is important when it comes to calculating the difference between calendar dates.

Knowing how the process works is, therefore critical.

There are various areas where the Julian date is used currently. Packaged foods for instance often come with Julian dates inscribed on them to help users establish the packing date.

It’s worth noting that the calculation process of Julian dates in food is different from the process in astronomy.

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