Friday the 13th

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A Friday the 13th occurs whenever the 13th day of a month is on a Friday. Such months are equivalently those that start on a Sunday. For example, the current year (2024) has Friday the 13ths on September 13 and December 13.

Correspondence with dominical letters

The Friday the 13ths in a year depend on its dominical letter. There could be 1, 2, or 3 of them in a single year.

Friday the 13ths
Common or leap Year starts on Dominical letter First Friday the 13th Second Friday the 13th Third Friday the 13th
Common year Sunday A January 13 October 13
Monday G April 13 July 13
Tuesday F September 13 December 13
Wednesday E June 13
Thursday D February 13 March 13 November 13
Friday C August 13
Saturday B May 13
Leap year Sunday AG January 13 April 13 July 13
Monday GF September 13 December 13
Tuesday FE June 13
Wednesday ED March 13 November 13
Thursday DC February 13 August 13
Friday CB May 13
Saturday BA October 13

Julian calendar

Friday the 13ths occur 48 times in the 28-year cycle of the Julian calendar (4 occurrences for each month of the year). January 13 and February 13 (in italics below) are for common years only, while January 13 and February 13 (in bold below) are for leap years only.

28-year cycle
Year mod 28 0 1 2 3 4 5
6 7 8 9 10 11
12 13 14 15 16
17 18 19 20 21 22
23 24 25 26 27
Friday the 13ths February 13 May 13 January 13 January 13 September 13 June 13 February 13
August 13 October 13 April 13 December 13 March 13
July 13 November 13

Gregorian calendar

Friday the 13ths occur 688 times in the 400-year cycle of the Gregorian calendar. January 13 and February 13 (in italics below) are for common years only, while January 13 and February 13 (in bold below) are for leap years only.

400-year cycle
Year mod 400 0 1 2 3 4 5
6 7 8 9 10 11
12 13 14 15 16
17 18 19 20 21 22
23 24 25 26 27
28 29 30 31 32 33
34 35 36 37 38 39
40 41 42 43 44
45 46 47 48 49 50
51 52 53 54 55
56 57 58 59 60 61
62 63 64 65 66 67
68 69 70 71 72
73 74 75 76 77 78
79 80 81 82 83
84 85 86 87 88 89
90 91 92 93 94 95
96 97 98 99 100 101
102 103 104 105 106 107
108 109 110 111 112
113 114 115 116 117 118
119 120 121 122 123
124 125 126 127 128 129
130 131 132 133 134 135
136 137 138 139 140
141 142 143 144 145 146
147 148 149 150 151
152 153 154 155 156 157
158 159 160 161 162 163
164 165 166 167 168
169 170 171 172 173 174
175 176 177 178 179
180 181 182 183 184 185
186 187 188 189 190 191
192 193 194 195 196
197 198 199 200 201 202 203
204 205 206 207 208
209 210 211 212 213 214
215 216 217 218 219
220 221 222 223 224 225
226 227 228 229 230 231
232 233 234 235 236
237 238 239 240 241 242
243 244 245 246 247
248 249 250 251 252 253
254 255 256 257 258 259
260 261 262 263 264
265 266 267 268 269 270
271 272 273 274 275
276 277 278 279 280 281
282 283 284 285 286 287
288 289 290 291 292
293 294 295 296 297 298
299 300 301 302 303 304
305 306 307 308 309 310
311 312 313 314 315
316 317 318 319 320 321
322 323 324 325 326 327
328 329 330 331 332
333 334 335 336 337 338
339 340 341 342 343
344 345 346 347 348 349
350 351 352 353 354 355
356 357 358 359 360
361 362 363 364 365 366
367 368 369 370 371
372 373 374 375 376 377
378 379 380 381 382 383
384 385 386 387 388
389 390 391 392 393 394
395 396 397 398 399
Friday the 13ths January 13 January 13 September 13 June 13 February 13 February 13 May 13
October 13 April 13 December 13 March 13 August 13
July 13 November 13