The International Fixed Calendar

The International Fixed Calendar (also known as the Cotsworth Calendar or the 13-Month Calendar) is a proposed reform of the Gregorian calendar designed to be more logical, practical, and easier to use.

Key Features:

  • 13 Equal Months: Each month has exactly 28 days (4 perfect weeks)
  • Consistent Week Structure: Every month begins on Sunday and ends on Saturday
  • New Month "Sol": Positioned between June and July
  • Year Day: December 31st falls outside the regular calendar (Day 0)
  • Leap Day: In leap years, an extra day appears between Sol 14th and Sol 15th
  • 365 Days: Same total days as the Gregorian calendar (366 in leap years)

This calendar provides perfect regularity, making scheduling, business planning, and daily life more predictable. Each date always falls on the same day of the week every year.

Learn more at the International Fixed Calendar Wikipedia page.

New Year's Day (Day 0)

Year DayDec 31

This day falls outside of any week or month. It occurs between Saturday, December 28th and Sunday, January 1st.

January

SundayMondayTuesdayWednesdayThursdayFridaySaturday
1
1
1
  • intlNew Year's Day
Jan 1
2
2
Jan 2
3
3
Jan 3
4
4
Jan 4
5
5
Jan 5
6
6
Jan 6
7
7
Jan 7
2
8
8
Jan 8
9
9
Jan 9
10
10
Jan 10
11
11
Jan 11
12
12
Jan 12
13
13
Jan 13
14
14
Jan 14
3
15
15
  • usUSgvMLK Jr. Day
  • intlWorld Religion Day
Jan 15
16
16
Jan 16
17
17
Jan 17
18
18
Jan 18
19
19
Jan 19
20
20
Jan 20
21
21
Jan 21
4
22
22
Jan 22
23
23
Jan 23
24
24
Jan 24
25
25
Jan 25
26
26
Jan 26
27
27
Jan 27
28
28
Jan 28

February

SundayMondayTuesdayWednesdayThursdayFridaySaturday
5
29
1
Jan 29
30
2
  • usintlGroundhog Day
Jan 30
31
3
Jan 31
32
4
Feb 1
33
5
Feb 2
34
6
Feb 3
35
7
Feb 4
6
36
8
Feb 5
37
9
  • brBRcvCarnival
Feb 6
38
10
Feb 7
39
11
Feb 8
40
12
Feb 9
41
13
Feb 10
42
14
  • intlValentine's Day
Feb 11
7
43
15
Feb 12
44
16
Feb 13
45
17
Feb 14
46
18
Feb 15
47
19
  • usUSgvPresidents' Day
Feb 16
48
20
Feb 17
49
21
Feb 18
8
50
22
Feb 19
51
23
Feb 20
52
24
Feb 21
53
25
Feb 22
54
26
Feb 23
55
27
Feb 24
56
28
Feb 25

March

SundayMondayTuesdayWednesdayThursdayFridaySaturday
9
57
1
Feb 26
58
2
Feb 27
59
3
Feb 28
60
4
Mar 1
61
5
Mar 2
62
6
Mar 3
63
7
Mar 4
10
64
8
Mar 5
65
9
Mar 6
66
10
Mar 7
67
11
Mar 8
68
12
Mar 9
69
13
Mar 10
70
14
Mar 11
11
71
15
Mar 12
72
16
Mar 13
73
17
  • ieintlSt. Patrick's Day
Mar 14
74
18
Mar 15
75
19
Mar 16
76
20
  • intlSpring Equinox
Mar 17
77
21
Mar 18
12
78
22
Mar 19
79
23
Mar 20
80
24
Mar 21
81
25
Mar 22
82
26
Mar 23
83
27
Mar 24
84
28
Mar 25

April

SundayMondayTuesdayWednesdayThursdayFridaySaturday
13
85
1
  • intlApril Fools' Day
Mar 26
86
2
Mar 27
87
3
Mar 28
88
4
Mar 29
89
5
Mar 30
90
6
Mar 31
91
7
Apr 1
14
92
8
Apr 2
93
9
Apr 3
94
10
Apr 4
95
11
Apr 5
96
12
Apr 6
97
13
Apr 7
98
14
Apr 8
15
99
15
  • intlEaster Sunday
  • usUSrlTax Day
Apr 9
100
16
Apr 10
101
17
Apr 11
102
18
  • brBRgvPaixão de Cristo
Apr 12
103
19
Apr 13
104
20
Apr 14
105
21
  • brBRgvTiradentes' Day
Apr 15
16
106
22
  • intlEarth Day
Apr 16
107
23
Apr 17
108
24
Apr 18
109
25
Apr 19
110
26
Apr 20
111
27
Apr 21
112
28
Apr 22

May

SundayMondayTuesdayWednesdayThursdayFridaySaturday
17
113
1
  • intlInternational Workers' Day
  • brBRgvDia do Trabalho
Apr 23
114
2
Apr 24
115
3
Apr 25
116
4
Apr 26
117
5
  • mxintlCinco de Mayo
Apr 27
118
6
Apr 28
119
7
Apr 29
18
120
8
Apr 30
121
9
May 1
122
10
May 2
123
11
May 3
124
12
  • intlMother's Day
May 4
125
13
May 5
126
14
May 6
19
127
15
May 7
128
16
May 8
129
17
May 9
130
18
May 10
131
19
May 11
132
20
May 12
133
21
May 13
20
134
22
May 14
135
23
May 15
136
24
May 16
137
25
May 17
138
26
May 18
139
27
  • usUSgvMemorial Day
May 19
140
28
May 20

June

SundayMondayTuesdayWednesdayThursdayFridaySaturday
21
141
1
May 21
142
2
May 22
143
3
May 23
144
4
May 24
145
5
May 25
146
6
May 26
147
7
May 27
22
148
8
May 28
149
9
May 29
150
10
May 30
151
11
May 31
152
12
Jun 1
153
13
Jun 2
154
14
  • usUSrlFlag Day
Jun 3
23
155
15
Jun 4
156
16
  • intlFather's Day
Jun 5
157
17
Jun 6
158
18
Jun 7
159
19
  • usUSgvJuneteenth
Jun 8
160
20
Jun 9
161
21
Jun 10
24
162
22
Jun 11
163
23
Jun 12
164
24
Jun 13
165
25
Jun 14
166
26
Jun 15
167
27
Jun 16
168
28
Jun 17

Sol

SundayMondayTuesdayWednesdayThursdayFridaySaturday
25
169
1
Jun 18
170
2
Jun 19
171
3
Jun 20
172
4
  • usUSgvIndependence Day
  • intlSol Freedom Day
  • festFireworks Day
  • +2 more...
Jun 21
173
5
Jun 22
174
6
Jun 23
175
7
Jun 24
26
176
8
Jun 25
177
9
Jun 26
178
10
Jun 27
179
11
Jun 28
180
12
Jun 29
181
13
Jun 30
182
14
Jul 1
27
183
15
Jul 2
184
16
Jul 3
185
17
Jul 4
186
18
Jul 5
187
19
Jul 6
188
20
Jul 7
189
21
Jul 8
28
190
22
Jul 9
191
23
Jul 10
192
24
Jul 11
193
25
Jul 12
194
26
Jul 13
195
27
Jul 14
196
28
Jul 15

July

SundayMondayTuesdayWednesdayThursdayFridaySaturday
29
197
1
Jul 16
198
2
Jul 17
199
3
Jul 18
200
4
Jul 19
201
5
Jul 20
202
6
Jul 21
203
7
Jul 22
30
204
8
Jul 23
205
9
Jul 24
206
10
Jul 25
207
11
Jul 26
208
12
Jul 27
209
13
Jul 28
210
14
Jul 29
31
211
15
  • usintlMoon Landing Day
Jul 30
212
16
Jul 31
213
17
Aug 1
214
18
Aug 2
215
19
Aug 3
216
20
Aug 4
217
21
Aug 5
32
218
22
Aug 6
219
23
Aug 7
220
24
Aug 8
221
25
Aug 9
222
26
Aug 10
223
27
Aug 11
224
28
Aug 12

August

SundayMondayTuesdayWednesdayThursdayFridaySaturday
33
225
1
  • intlInternational Beer Day
Aug 13
226
2
Aug 14
227
3
Aug 15
228
4
Aug 16
229
5
Aug 17
230
6
Aug 18
231
7
Aug 19
34
232
8
Aug 20
233
9
Aug 21
234
10
Aug 22
235
11
Aug 23
236
12
Aug 24
237
13
Aug 25
238
14
Aug 26
35
239
15
Aug 27
240
16
Aug 28
241
17
Aug 29
242
18
Aug 30
243
19
Aug 31
244
20
Sep 1
245
21
Sep 2
36
246
22
Sep 3
247
23
Sep 4
248
24
Sep 5
249
25
Sep 6
250
26
Sep 7
251
27
Sep 8
252
28
Sep 9

September

SundayMondayTuesdayWednesdayThursdayFridaySaturday
37
253
1
Sep 10
254
2
  • usUSgvLabor Day
Sep 11
255
3
Sep 12
256
4
Sep 13
257
5
Sep 14
258
6
Sep 15
259
7
  • brBRgvIndependence Day
Sep 16
38
260
8
Sep 17
261
9
Sep 18
262
10
Sep 19
263
11
Sep 20
264
12
Sep 21
265
13
Sep 22
266
14
Sep 23
39
267
15
Sep 24
268
16
Sep 25
269
17
Sep 26
270
18
Sep 27
271
19
Sep 28
272
20
Sep 29
273
21
Sep 30
40
274
22
  • intlAutumn Equinox
Oct 1
275
23
Oct 2
276
24
Oct 3
277
25
Oct 4
278
26
Oct 5
279
27
Oct 6
280
28
Oct 7

October

SundayMondayTuesdayWednesdayThursdayFridaySaturday
41
281
1
Oct 8
282
2
Oct 9
283
3
Oct 10
284
4
Oct 11
285
5
Oct 12
286
6
Oct 13
287
7
Oct 14
42
288
8
Oct 15
289
9
Oct 16
290
10
Oct 17
291
11
Oct 18
292
12
  • brBRrlNossa Senhora Aparecida
Oct 19
293
13
Oct 20
294
14
  • usUSgvColumbus Day
Oct 21
43
295
15
Oct 22
296
16
Oct 23
297
17
Oct 24
298
18
Oct 25
299
19
Oct 26
300
20
Oct 27
301
21
Oct 28
44
302
22
Oct 29
303
23
Oct 30
304
24
Oct 31
305
25
Nov 1
306
26
Nov 2
307
27
Nov 3
308
28
Nov 4

November

SundayMondayTuesdayWednesdayThursdayFridaySaturday
45
309
1
Nov 5
310
2
  • brBRgvDia de Finados
Nov 6
311
3
Nov 7
312
4
Nov 8
313
5
Nov 9
314
6
Nov 10
315
7
Nov 11
46
316
8
Nov 12
317
9
Nov 13
318
10
Nov 14
319
11
  • usUSgvVeterans Day
Nov 15
320
12
Nov 16
321
13
Nov 17
322
14
Nov 18
47
323
15
  • brBRgvProclamação da República
Nov 19
324
16
Nov 20
325
17
Nov 21
326
18
Nov 22
327
19
Nov 23
328
20
  • brBRrlDia da Consciência Negra
Nov 24
329
21
Nov 25
48
330
22
Nov 26
331
23
Nov 27
332
24
Nov 28
333
25
Nov 29
334
26
Nov 30
335
27
Dec 1
336
28
  • usUSgvThanksgiving
Dec 2

December

SundayMondayTuesdayWednesdayThursdayFridaySaturday
49
337
1
Dec 3
338
2
Dec 4
339
3
Dec 5
340
4
Dec 6
341
5
Dec 7
342
6
Dec 8
343
7
Dec 9
50
344
8
Dec 10
345
9
Dec 11
346
10
Dec 12
347
11
Dec 13
348
12
Dec 14
349
13
Dec 15
350
14
Dec 16
51
351
15
Dec 17
352
16
Dec 18
353
17
Dec 19
354
18
Dec 20
355
19
Dec 21
356
20
Dec 22
357
21
Dec 23
52
358
22
Dec 24
359
23
Dec 25
360
24
Dec 26
361
25
  • intlChristmas Day
Dec 27
362
26
  • gbintlBoxing Day
Dec 28
363
27
Dec 29
364
28
Dec 30