<table border><tr><td></td><th align='center' colspan='8'>Year to letter</th></tr><tr align='right'><td></td>
<td> 0<br> 8<br>16<br>24<br>32<br>40<br>48<br>56<br>64<br>72<br>80<br>88<br>96</td>
<td> 1<br> 9<br>17<br>25<br>33<br>41<br>49<br>57<br>65<br>73<br>81<br>89<br>97</td>
<td> 2<br>10<br>18<br>26<br>34<br>42<br>50<br>58<br>66<br>74<br>82<br>90<br>98</td>
<td> 3<br>11<br>19<br>27<br>35<br>43<br>51<br>59<br>67<br>75<br>83<br>91<br>99</td>
<td> 4<br>12<br>20<br>28<br>36<br>44<br>52<br>60<br>68<br>76<br>84<br>92<br>&nbsp;</td>
<td> 5<br>13<br>21<br>29<br>37<br>45<br>53<br>61<br>69<br>77<br>85<br>93<br>&nbsp;</td>
<td> 6<br>14<br>22<br>30<br>38<br>46<br>54<br>62<br>70<br>78<br>86<br>94<br>&nbsp;</td>
<td> 7<br>15<br>23<br>31<br>39<br>47<br>55<br>63<br>71<br>79<br>87<br>95<br>&nbsp;</td>
</tr>
<tr align='center'><td>1792 - 1799</td><td>bfl</td><td>cfl</td><td>cfl</td><td>cfk</td><td>bfl</td><td>cfl</td><td>cfl</td><td>cfk</td></tr>
<tr align='center'><td>1800 - 1803</td><td>bek</td><td>bek</td><td>bek</td><td>bej</td><td>bek</td><td>bek</td><td>bek</td><td>bej</td></tr>
<tr align='center'><td>1804 - 1807</td><td>aek</td><td>bek</td><td>bek</td><td>bej</td><td>aek</td><td>bek</td><td>bek</td><td>bej</td></tr>
<tr align='center'><td>1808 - 1811</td><td>aek</td><td>bek</td><td>bek</td><td>bek</td><td>aek</td><td>bek</td><td>bek</td><td>bek</td></tr>
<tr align='center'><td>1812 - 1891</td><td>bfk</td><td>bek</td><td>bek</td><td>bek</td><td>bfk</td><td>bek</td><td>bek</td><td>bek</td></tr>
<tr align='center'><td>1892 - 1895</td><td>bfl</td><td>cfl</td><td>cfl</td><td>cfl</td><td>bfl</td><td>cfl</td><td>cfl</td><td>cfl</td></tr>
<tr align='center'><td>1896 - 1899</td><td>cgl</td><td>cfl</td><td>cfl</td><td>cfl</td><td>cgl</td><td>cfl</td><td>cfl</td><td>cfl</td></tr>
<tr align='center'><td>1900 - 1903</td><td>cfk</td><td>bek</td><td>bek</td><td>bek</td><td>cfk</td><td>bek</td><td>bek</td><td>bek</td></tr>
<tr align='center'><td>1904 - 1991</td><td>bfk</td><td>bek</td><td>bek</td><td>bek</td><td>bfk</td><td>bek</td><td>bek</td><td>bek</td></tr>
<tr align='center'><td>1992 - 1995</td><td>bfl</td><td>cfl</td><td>cfl</td><td>cfl</td><td>bfl</td><td>cfl</td><td>cfl</td><td>cfl</td></tr>
<tr align='center'><td>1996 - 2091</td><td>cgl</td><td>cfl</td><td>cfl</td><td>cfl</td><td>cgl</td><td>cfl</td><td>cfl</td><td>cfl</td></tr>
<tr align='center'><td>2092 - 2095</td><td>cgm</td><td>dgm</td><td>dgm</td><td>dgm</td><td>cgm</td><td>dgm</td><td>dgm</td><td>dgm</td></tr>
<tr align='center'><td>2096 - 2099</td><td>dhm</td><td>dgm</td><td>dgm</td><td>dgm</td><td>dhm</td><td>dgm</td><td>dgm</td><td>dgm</td></tr>
</table>
<p><table border><tr><th align='center' colspan='5'>Beginning of Year</th></tr>
<tr align='center'><th>Year - 1792</th><th>a</th><th>b</th><th>c</th><th>d</th></tr>
<tr align='center'><td>January</td><td>+9 Niv<br>-21 Plu</td>
<td>+10 Niv<br>-20 Plu</td>
<td>+11 Niv<br>-19 Plu</td>
<td>+12 Niv<br>-18 Plu</td>
</tr>
<tr align='center'><td>February</td><td>+10 Plu<br>-20 Vnt</td>
<td>+11 Plu<br>-19 Vnt</td>
<td>+12 Plu<br>-18 Vnt</td>
<td>+13 Plu<br>-17 Vnt</td>
</tr>
</table>
<p><table border><tr><th align='center' colspan='5'>Middle of Year</th></tr>
<tr align='center'><th>Year - 1792</th><th>e</th><th>f</th><th>g</th><th>h</th></tr>
<tr align='center'><td>March</td><td>+9 Vnt<br>-21 Ger</td>
<td>+10 Vnt<br>-20 Ger</td>
<td>+11 Vnt<br>-19 Ger</td>
<td>+12 Vnt<br>-18 Ger</td>
</tr>
<tr align='center'><td>April</td><td>+10 Ger<br>-20 Flo</td>
<td>+11 Ger<br>-19 Flo</td>
<td>+12 Ger<br>-18 Flo</td>
<td>+13 Ger<br>-17 Flo</td>
</tr>
<tr align='center'><td>May</td><td>+10 Flo<br>-20 Pra</td>
<td>+11 Flo<br>-19 Pra</td>
<td>+12 Flo<br>-18 Pra</td>
<td>+13 Flo<br>-17 Pra</td>
</tr>
<tr align='center'><td>June</td><td>+11 Pra<br>-19 Mes</td>
<td>+12 Pra<br>-18 Mes</td>
<td>+13 Pra<br>-17 Mes</td>
<td>+14 Pra<br>-16 Mes</td>
</tr>
<tr align='center'><td>July</td><td>+11 Mes<br>-19 The</td>
<td>+12 Mes<br>-18 The</td>
<td>+13 Mes<br>-17 The</td>
<td>+14 Mes<br>-16 The</td>
</tr>
<tr align='center'><td>August</td><td>+12 The<br>-18 Fru</td>
<td>+13 The<br>-17 Fru</td>
<td>+14 The<br>-16 Fru</td>
<td>+15 The<br>-15 Fru</td>
</tr>
<tr align='center'><td>September</td><td>+13 Fru<br>-17 S-C</td>
<td>+14 Fru<br>-16 S-C</td>
<td>+15 Fru<br>-15 S-C</td>
<td>+16 Fru<br>-14 S-C</td>
</tr>
</table>
<p><table border><tr><th align='center' colspan='5'>End of Year</th></tr>
<tr align='center'><th>Year - 1791</th><th>j</th><th>k</th><th>l</th><th>m</th></tr>
<tr align='center'><td>September</td><td>-23 Vnd</td>
<td>-22 Vnd</td>
<td>-21 Vnd</td>
<td>-20 Vnd</td>
</tr>
<tr align='center'><td>October</td><td>+7 Vnd<br>-23 Bru</td>
<td>+8 Vnd<br>-22 Bru</td>
<td>+9 Vnd<br>-21 Bru</td>
<td>+10 Vnd<br>-20 Bru</td>
</tr>
<tr align='center'><td>November</td><td>+8 Bru<br>-22 Fri</td>
<td>+9 Bru<br>-21 Fri</td>
<td>+10 Bru<br>-20 Fri</td>
<td>+11 Bru<br>-19 Fri</td>
</tr>
<tr align='center'><td>December</td><td>+8 Fri<br>-22 Niv</td>
<td>+9 Fri<br>-21 Niv</td>
<td>+10 Fri<br>-20 Niv</td>
<td>+11 Fri<br>-19 Niv</td>
</tr>
</table>
<p>
<p>
<table border>
<tr><th colspan='7'>Month names and day names</th></tr>
<tr><td>Vnd</td><td>Vendémiaire</td><td></td>
    <td align = 'right'>1</td><td align = 'right'>11</td><td align = 'right'>21</td>
    <td>Primedi / Primidi</td></tr>
<tr><td>Bru</td><td>Brumaire</td><td></td>
    <td align = 'right'>2</td><td align = 'right'>12</td><td align = 'right'>22</td>
    <td>Duodi</td></tr>
<tr><td>Fri</td><td>Frimaire</td><td></td>
    <td align = 'right'>3</td><td align = 'right'>13</td><td align = 'right'>23</td>
    <td>Tridi</td></tr>
<tr><td>Niv</td><td>Nivôse</td><td></td>
    <td align = 'right'>4</td><td align = 'right'>14</td><td align = 'right'>24</td>
    <td>Quartidi</td></tr>
<tr><td>Plu</td><td>Pluviôse</td><td></td>
    <td align = 'right'>5</td><td align = 'right'>15</td><td align = 'right'>25</td>
    <td>Quintidi</td></tr>
<tr><td>Vnt</td><td>Ventôse</td><td></td>
    <td align = 'right'>6</td><td align = 'right'>16</td><td align = 'right'>26</td>
    <td>Sextidi</td></tr>
<tr><td>Ger</td><td>Germinal</td><td></td>
    <td align = 'right'>7</td><td align = 'right'>17</td><td align = 'right'>27</td>
    <td>Septidi</td></tr>
<tr><td>Flo</td><td>Floréal</td><td></td>
    <td align = 'right'>8</td><td align = 'right'>18</td><td align = 'right'>28</td>
    <td>Octidi</td></tr>
<tr><td>Pra</td><td>Prairial</td><td></td>
    <td align = 'right'>9</td><td align = 'right'>19</td><td align = 'right'>29</td>
    <td>Nonidi</td></tr>
<tr><td>Mes</td><td>Messidor</td><td></td>
    <td align = 'right'>10</td><td align = 'right'>20</td><td align = 'right'>30</td>
    <td>Décadi</td></tr>
<tr><td>The</td><td>Thermidor</td></tr>
<tr><td>Fru</td><td>Fructidor</td></tr>
<tr><td>S-C</td><td colspan='7'>Sans-Culottides / Additional Days</td></tr>
</table>
<p>
<p>
<h3>How to convert 09 November 1799</h3>
<p>Look at the first table. The Gregorian year <strong>1799</strong> belongs to the interval
<em>1792&nbsp;-&nbsp;1799</em> and its last two digits are 
<em>99</em>. 
The cell in the corresponding
line and column contains the three letters <em>cfk</em>. 
<p>Look at the next three tables. 
The month <strong>November</strong> appears in the <em>End of Year</em> table, at
the head of which is the fomula <em>Year&nbsp;-&nbsp;1791</em>.
So you can compute that the French Revolutionary year is <strong>8</strong>.
Of the three letters <em>cfk</em>, the letter <em>k</em> appears
in the same table. The corresponding cell contains two formulas: 
<em>+9 Bru -21 Fri</em>. Choose the one that will convert the day number <strong>09</strong>
into a number in the 1-30 range. That is, up to and including 
<strong>21 November</strong>, use
the first formula <em>+9 Bru</em>, and later use the second formula <em>-21 Fri</em>.
Since the Gregorian day number is <strong>09</strong>, you use <em>+9 Bru</em>, and you get
<strong>18 Bru</strong>. The final step consists in retrieving the day's full name
and the month's full name in the last table, which gives 
<strong>Octidi 18 Brumaire VIII</strong>.

<h3>How to convert 09 September 1799</h3>
<p>What about September? The first step is the same, and gives the same three letters 
<em>cfk</em>.
<p>But <strong>September</strong> 
appears both in the 
<em>Middle of Year</em> 
table, and in the 
<em>End of Year</em> 
table. The first one gives two formulas for the day: 
<em>+14 Fru</em> 
and 
<em>-16 S-C</em> (<em>f</em>
column), and one for the year: 
<em>Year&nbsp;-&nbsp;1792</em>. 
The second table gives 
<em>-22 Vnd</em> for the day 
(<em>k</em>
column) and 
<em>Year&nbsp;-&nbsp;1791</em>
for the year. 
<p>Try the last formula <em>-22 Vnd</em>,
then the prior one <em>-16 S-C</em>, then the first one <em>+14 Fru</em>, 
until you have a result greater than or equal to 1.
<p>For <strong>09 September 1799</strong>, you would choose <em>+14 Fru</em>,
with the corresponding year formula <em>Year&nbsp;-&nbsp;1792</em>,
which gives you <strong>23 Fru 0007</strong>, or better
<strong>Tridi 23 Fructidor VII</strong>.