There's no sense being exact about something if you don't even know what you're talking about. --John von Neumann

Hexadecimal (Hex) to Decimal Lookup Table

Easily convert hex to decimal and back again with this convenient table

Summary

QUESTION: How do I easily convert hexadecimal numbers to decimal numbers and vice versa in a simple lookup table.

The table immediately follows, but see page 2 for the C# code that generated the table.

Hex To Decimal Lookup Table

D: 0-15
X: 0-F
DecHex
00
11
22
33
44
55
66
77
88
99
10A
11B
12C
13D
14E
15F
D: 16-31
X: 10-1F
DecHex
1610
1711
1812
1913
2014
2115
2216
2317
2418
2519
261A
271B
281C
291D
301E
311F
D: 32-47
X: 20-2F
DecHex
3220
3321
3422
3523
3624
3725
3826
3927
4028
4129
422A
432B
442C
452D
462E
472F
D: 48-63
X: 30-3F
DecHex
4830
4931
5032
5133
5234
5335
5436
5537
5638
5739
583A
593B
603C
613D
623E
633F
D: 64-79
X: 40-4F
DecHex
6440
6541
6642
6743
6844
6945
7046
7147
7248
7349
744A
754B
764C
774D
784E
794F
D: 80-95
X: 50-5F
DecHex
8050
8151
8252
8353
8454
8555
8656
8757
8858
8959
905A
915B
925C
935D
945E
955F
D: 96-111
X: 60-6F
DecHex
9660
9761
9862
9963
10064
10165
10266
10367
10468
10569
1066A
1076B
1086C
1096D
1106E
1116F
D: 112-127
X: 70-7F
DecHex
11270
11371
11472
11573
11674
11775
11876
11977
12078
12179
1227A
1237B
1247C
1257D
1267E
1277F
D: 128-143
X: 80-8F
DecHex
12880
12981
13082
13183
13284
13385
13486
13587
13688
13789
1388A
1398B
1408C
1418D
1428E
1438F
D: 144-159
X: 90-9F
DecHex
14490
14591
14692
14793
14894
14995
15096
15197
15298
15399
1549A
1559B
1569C
1579D
1589E
1599F
D: 160-175
X: A0-AF
DecHex
160A0
161A1
162A2
163A3
164A4
165A5
166A6
167A7
168A8
169A9
170AA
171AB
172AC
173AD
174AE
175AF
D: 176-191
X: B0-BF
DecHex
176B0
177B1
178B2
179B3
180B4
181B5
182B6
183B7
184B8
185B9
186BA
187BB
188BC
189BD
190BE
191BF
D: 192-207
X: C0-CF
DecHex
192C0
193C1
194C2
195C3
196C4
197C5
198C6
199C7
200C8
201C9
202CA
203CB
204CC
205CD
206CE
207CF
D: 208-223
X: D0-DF
DecHex
208D0
209D1
210D2
211D3
212D4
213D5
214D6
215D7
216D8
217D9
218DA
219DB
220DC
221DD
222DE
223DF
D: 224-239
X: E0-EF
DecHex
224E0
225E1
226E2
227E3
228E4
229E5
230E6
231E7
232E8
233E9
234EA
235EB
236EC
237ED
238EE
239EF
D: 240-255
X: F0-FF
DecHex
240F0
241F1
242F2
243F3
244F4
245F5
246F6
247F7
248F8
249F9
250FA
251FB
252FC
253FD
254FE
255FF

Why I Programmed a Hex to Dec Lookup Table?

So I'm sitting at my computer developing a website. I'm tweaking the colors trying to get 'em right. I try burlywood, cornflowerblue, saddlebrown and a few others. But I need more subtlety than the standard named colors. One of my graphics applications has a color picker eye-dropper so I decide to pull some colors off of one of the images.

Unfortunately, that application only gives me the decimal RGB values for the color. But I need a hex value to put in my stylesheet. So I go to Start->Programs->Accessories->Calculator and start typing in decimal numbers between 0 and 255 to determine their hex value. But I have 8 colors which amounts to 24 numbers I need to convert. This is going to take forever!

So I decided I needed a convenient lookup table. It wouldn't be fast exactly, but it would certainly speed things up. So I wrote a little program in C# to generate the table. And there it is above.

If you're interested in the C# method that generates the table, click to the next page.

C# Code to General Hex to Decimal Lookup Table

Following is the C# code I wrote to generate the hexadecimal to decimal lookup table found on page 1.

Add the method to the code-behind page of an ASPX page. Be sure to add a Label named lblOutput and don't forget 'using System.Text' because I use the StringBuilder class to speed things up a bit.

(Obviously, you can adapt this for Windows Forms or console application, etc...)

C# Method. Generate Decimal to Hexadecimal Lookup Table

public void GenerateHexDecConversionTable()
{
   StringBuilder sb = new StringBuilder();

   sb.Append("<table cellpadding=15 cellspacing=0 "
   + "border=1 border-color=gainsboro>");

   for (int i=0; i<256; i++)
   {
      if ( i%(16) == 0) // if we're beginning a new multiple of 16
      {
         if (i != 0) // if it's not the first multiple of 16
            sb.Append("</table cellpadding=4 cellspacing=0></td>");
         if ( i%64 == 0) // if we're beginning a new multiple of 64
         {
            if (i != 0) // if it's not the first multiple of 64
               sb.Append("</tr>");
            sb.Append("<tr>");
         }
         sb.Append("<td align=center><table>");
         sb.Append("<tr><td colspan=2><B>D: </b>"
          + i.ToString() + "-" + (i+15).ToString() 
          + "</td></tr>");
         sb.Append("<tr><td colspan=2><b>X: </b>" 
         + i.ToString("X") + "-" + (i+15).ToString("X") 
         + "</td></tr>");
         sb.Append("<tr><td align=center><b>Dec</b></td>"
         + "<td><b>Hex</b></td></tr>");
      }
      if (i%2 == 0)
      {
         sb.Append("<tr><td align=center "
         + "style='font-weight:bold;background-color:black;color:white;'>" 
         + i.ToString() + "</td><td align=center "
         + "style='font-weight:bold;background-color:white;color:black;'>" 
         + i.ToString("X") + "</td></tr>");
      }
      else
      {
         sb.Append("<tr><td align=center "
         + "style="
         + "'font-weight:bold;background-color:dimgray;color:white;'>" 
         + i.ToString() + "</td><td align=center "
         + "style="
         + "'font-weight:bold;background-color:gainsboro;color:black;'>" 
         + i.ToString("X") + "</td></tr>");
      }
   }

   sb.Append("</table></td></tr>");
   sb.Append("</table>");

   lblOutput.Text = sb.ToString();
}