| Year to letter | ||||||||
|---|---|---|---|---|---|---|---|---|
| 0 8 16 24 32 40 48 56 64 72 80 88 96 |
1 9 17 25 33 41 49 57 65 73 81 89 97 |
2 10 18 26 34 42 50 58 66 74 82 90 98 |
3 11 19 27 35 43 51 59 67 75 83 91 99 |
4 12 20 28 36 44 52 60 68 76 84 92 |
5 13 21 29 37 45 53 61 69 77 85 93 |
6 14 22 30 38 46 54 62 70 78 86 94 |
7 15 23 31 39 47 55 63 71 79 87 95 |
|
| 1 - 8 | ch | bg | bg | bg | cg | bg | bg | bg |
| 9 - 19 | dh | ch | ch | ch | dh | ch | ch | ch |
| 20 - 100 | cg | ch | ch | ch | cg | ch | ch | ch |
| 101 - 108 | bg | bg | bg | bg | bf | bg | bg | bg |
| 109 - 200 | cg | ch | ch | ch | cg | ch | ch | ch |
| 201 - 300 | bf | bg | bg | bg | bf | bg | bg | bg |
| 301 - 308 | af | af | af | af | ae | af | af | af |
| 309 - 400 | bf | bg | bg | bg | bf | bg | bg | bg |
| Beginning of Year | ||||
|---|---|---|---|---|
| Year + 1791 | a | b | c | d |
| Vendémiaire | +20 Sep -10 Oct |
+21 Sep -9 Oct |
+22 Sep -8 Oct |
+23 Sep -7 Oct |
| Brumaire | +20 Oct -11 Nov |
+21 Oct -10 Nov |
+22 Oct -9 Nov |
+23 Oct -8 Nov |
| Frimaire | +19 Nov -11 Dec |
+20 Nov -10 Dec |
+21 Nov -9 Dec |
+22 Nov -8 Dec |
| Nivôse | +19 Dec | +20 Dec | +21 Dec | +22 Dec |
| Year + 1792 | a | b | c | d |
| Nivôse | -12 Jan | -11 Jan | -10 Jan | -9 Jan |
| Pluviôse | +18 Jan -13 Feb |
+19 Jan -12 Feb |
+20 Jan -11 Feb |
+21 Jan -10 Feb |
| Ventôse | +17 Feb | +18 Feb | +19 Feb | +20 Feb |
| End of Year | ||||
|---|---|---|---|---|
| Year + 1792 | e | f | g | h |
| Ventôse | -12 Mar | -11 Mar | -10 Mar | -9 Mar |
| Germinal | +18 Mar -13 Apr |
+19 Mar -12 Apr |
+20 Mar -11 Apr |
+21 Mar -10 Apr |
| Floréal | +17 Apr -13 May |
+18 Apr -12 May |
+19 Apr -11 May |
+20 Apr -10 May |
| Prairial | +17 May -14 Jun |
+18 May -13 Jun |
+19 May -12 Jun |
+20 May -11 Jun |
| Messidor | +16 Jun -14 Jul |
+17 Jun -13 Jul |
+18 Jun -12 Jul |
+19 Jun -11 Jul |
| Thermidor | +16 Jul -15 Aug |
+17 Jul -14 Aug |
+18 Jul -13 Aug |
+19 Jul -12 Aug |
| Fructidor | +15 Aug -16 Sep |
+16 Aug -15 Sep |
+17 Aug -14 Sep |
+18 Aug -13 Sep |
| Sans-Culottides Additional Days | +14 Sep | +15 Sep | +16 Sep | +17 Sep |
Look at the first table. The French Revolutionary year 8 belongs to the interval 1 - 8 and its last two digits are 08. The cell in the corresponding line and column contains the two letters ch.
Look at the next two tables. The month Brumaire appears in the Beginning of Year table. Of the two letters ch, the letter c appears in the same table. The corresponding cell contains two formulas: +22 Oct -9 Nov. Choose the one that will convert the day number 18 into a number in the proper range for the Gregorian month. That is, up to and including 9 Brumaire, use the first formula +22 Oct, and later use the second formula -9 Nov. Since the French Revolutionary day number is 18, you use -9 Nov. Using the year formula next to the column headers, you get 9 November 1799.
For Additional Days, there is only one formula, which is much simpler.
For Nivôse, the cell is split in two, because there are two formulas for the year, Year + 1791 and Year + 1792.
Ventôse is in both tables. For Ventôse 8, in column c you obtain the +19 Feb formula, and in column h you obtain the -9 Mar formula. Except for that, everything else is the same. That is, up to and including 9 Ventôse, use the first formula +19 Feb, and later use the second formula -9 Mar. For example, if you want to convert 18 Ventôse VIII, since the French Revolutionary day number is 18, you use -9 Mar, and you get 9 March 1800.