What is a Julian Date?

Written by The Ready Store

We often get the question of why an MRE doesn’t have an expiration date printed on it.

You may have noticed that your MRE’s have a funny number at the bottom. What is that thing? This is a Julian Date or code.

Where did Julian Dates come from?

Julian Dates, abbreviated JD, are simply a continuous count of days and fractions since noon Universal Time on January 1, 4713 BCE (on the Julian calendar). Ha, clear as mud right?

Basically, Jan. 1, 4713 BCE was day 1. Jan. 2, 4713 was day 2 and so forth. However, almost 2.5 million days have transpired since this date.  Julian dates are widely used as time variables within astronomical software.

A military MRE in action

The changeover from the Julian calendar to the Gregorian calendar occurred in October of 1582, according to the scheme instituted by Pope Gregory XIII.

The changeover to the Gregorian calendar system occurred  only in Roman Catholic countries. Adoption of the Gregorian calendar in the rest of the world progressed slowly. For example, for England and its colonies, the change did not occur until September 1752.

Why use Julian Dates?

MRE’s use Julian Dates because they originated with the military. The time scale that is the basis for Julian dates is Universal Time.

Julian dates useful for the Military because the procurement systems in the military uses the Julian date in the computer programs as a simple standard that doesn’t require letters and allows date calculations to be made with out additional supporting programs.

Many times, manufactures use Julian Dates because that is the norm in the industry. However, with consumer knowledge on the rise, many manufacturers are moving towards a more readable manufacture date.

How do I read my Julian Date?

You can check out The Ready Store’s MRE Shelf-Life Calculator on the left side bar of our product pages.

The first number of the Julian Date represents the year. The last three numbers represent the day that it was manufactured. So for example, if the manufacture date was listed as 1067 that would mean that the MRE was manufactured on March 7, 2011. You can read our previous blog post on how to figure out the manufacture date of your MRE.

After locating your manufacture date, use this conversion chart to figure out the date of your MRE.

 

Day of Month Jan

1 

Feb

2 

March

3 

April

4 

May

5 

June

6 

July

7 

Aug

8 

Sept

9 

Oct

10 

Nov

11 

Dec

12 

1st 001 032 061 092 122 153 183 214 245 275 306 336
2nd 002 033 062 093 123 154 184 215 246 276 307 337
3rd 003 034 063 094 124 155 185 216 247 277 308 338
4th 004 035 064 095 125 156 186 217 248 278 309 339
5th 005 036 065 096 126 157 187 218 2249 279 310 340
6th 006 037 066 097 127 158 188 219 250 280 311 341
7th 007 038 067 098 128 159 189 220 251 281 312 342
8th 008 039 068 099 129 160 190 221 252 282 313 343
9th 009 040 069 100 130 161 191 222 253 283 314 344
10th 010 041 070 101 131 162 192 223 254 284 315 345
11th 011 042 071 102 132 163 193 224 255 285 316 346
12th 012 043 072 103 133 164 194 225 256 286 317 347
13th 013 044 073 104 134 165 195 226 257 287 318 348
14th 014 045 074 105 135 166 196 227 258 288 319 349
15th 015 046 075 106 136 167 197 228 259 289 320 350
16th 016 047 076 107 137 168 198 229 260 290 321 351
17th 017 048 077 108 138 169 199 230 261 291 322 352
18th 018 049 078 109 139 170 200 231 262 292 323 353
19th 019 050 079 110 140 171 201 232 263 293 324 354
20th 020 051 080 111 141 172 202 233 264 294 325 355
21st 021 052 081 112 142 173 203 234 265 295 326 356
22nd 022 053 082 113 143 174 204 235 266 296 327 357
23rd 023 054 083 114 144 175 205 236 267 297 328 358
24th 024 055 084 115 145 176 206 237 268 298 329 359
25th 025 056 085 116 146 177 207 238 269 299 330 360
26th 026 057 086 117 147 178 208 239 270 300 331 361
27th 027 058 087 118 148 179 209 240 271 301 332 362
28th 028 059 088 119 149 180 210 241 272 302 333 363
29th 029 060 089 120 150 181 211 242 273 303 334 364
30th 030 ——- 090 121 151 182 212 243 274 304 335 365
31st 031 ——- 091 ——- 152 ——- 213 244 ——- 305 ——- 366

We also have a sheet that you can print out and keep with your MREs in case of an emergency.

Click here to see the PDF. 

Questions?

What other questions do you have about Julian Dates? Ask us below.

Updated March 29, 2010

7 Comments

  1. Jason wrote:

    Actually the date codes on MREs are not technically a “Julian date”. The date codes are a form of “Ordinal date”, usually in the form of YYDDD where “YY” is the last two digits of the year and DDD are the ordinal day of the year.

    April 6th, 2010 at 7:55 am
  2. Captain wrote:

    I guess this would matter if it was your birthday. What if you look at Dec 20,2012 as being the end of the Mayan calander? What would that be in Julian, or Ordinal days?

    April 7th, 2010 at 5:05 am
  3. Jason wrote:

    It does make a difference if you want to be correct. Today’s Julian Date is: JD 2455295

    Today’s Ordinal Date is: 10099

    April 9th, 2010 at 7:14 am
  4. Bev wrote:

    A Christmas gift I received said the Julian date was 095????? Today’s date is 12/20/2013. Thanks for your help. So what is the Julian date in case this gift has expired?

    December 20th, 2013 at 7:19 pm
  5. Bev wrote:

    A Christmas gift I received said the Julian date was 095. So what does that mean and has the gift expired? Thanks for your help

    December 20th, 2013 at 7:21 pm
  6. aps wrote:

    what is the advantage of using julian date over any other systems??

    March 26th, 2014 at 10:06 pm
  7. Steve wrote:

    So I’m hunkered down in my bunker for no other reason than I’m an old curmudgeon. My idiot offspring keep ordering MREs for ten years, but don’t rotate the stock.
    How will I know if I’m eating something from one year to 19 years old?

    March 31st, 2014 at 6:39 pm

What Do You Think of That?