Err and err and err again, but less and less and less. --Piet Hein

Hexadecimal (Hex) to Decimal Lookup Table

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

By Steve on Sunday, January 07, 2007
Updated Friday, April 22, 2016
Viewed 592,233 times. (13 times today.)

Developer Tools and Tables Math

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
Dec	Hex
0	0
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	8
9	9
10	A
11	B
12	C
13	D
14	E
15	F

D: 16-31
X: 10-1F
Dec	Hex
16	10
17	11
18	12
19	13
20	14
21	15
22	16
23	17
24	18
25	19
26	1A
27	1B
28	1C
29	1D
30	1E
31	1F

D: 32-47
X: 20-2F
Dec	Hex
32	20
33	21
34	22
35	23
36	24
37	25
38	26
39	27
40	28
41	29
42	2A
43	2B
44	2C
45	2D
46	2E
47	2F

D: 48-63
X: 30-3F
Dec	Hex
48	30
49	31
50	32
51	33
52	34
53	35
54	36
55	37
56	38
57	39
58	3A
59	3B
60	3C
61	3D
62	3E
63	3F

D: 64-79
X: 40-4F
Dec	Hex
64	40
65	41
66	42
67	43
68	44
69	45
70	46
71	47
72	48
73	49
74	4A
75	4B
76	4C
77	4D
78	4E
79	4F

D: 80-95
X: 50-5F
Dec	Hex
80	50
81	51
82	52
83	53
84	54
85	55
86	56
87	57
88	58
89	59
90	5A
91	5B
92	5C
93	5D
94	5E
95	5F

D: 96-111
X: 60-6F
Dec	Hex
96	60
97	61
98	62
99	63
100	64
101	65
102	66
103	67
104	68
105	69
106	6A
107	6B
108	6C
109	6D
110	6E
111	6F

D: 112-127
X: 70-7F
Dec	Hex
112	70
113	71
114	72
115	73
116	74
117	75
118	76
119	77
120	78
121	79
122	7A
123	7B
124	7C
125	7D
126	7E
127	7F

D: 128-143
X: 80-8F
Dec	Hex
128	80
129	81
130	82
131	83
132	84
133	85
134	86
135	87
136	88
137	89
138	8A
139	8B
140	8C
141	8D
142	8E
143	8F

D: 144-159
X: 90-9F
Dec	Hex
144	90
145	91
146	92
147	93
148	94
149	95
150	96
151	97
152	98
153	99
154	9A
155	9B
156	9C
157	9D
158	9E
159	9F

D: 160-175
X: A0-AF
Dec	Hex
160	A0
161	A1
162	A2
163	A3
164	A4
165	A5
166	A6
167	A7
168	A8
169	A9
170	AA
171	AB
172	AC
173	AD
174	AE
175	AF

D: 176-191
X: B0-BF
Dec	Hex
176	B0
177	B1
178	B2
179	B3
180	B4
181	B5
182	B6
183	B7
184	B8
185	B9
186	BA
187	BB
188	BC
189	BD
190	BE
191	BF

D: 192-207
X: C0-CF
Dec	Hex
192	C0
193	C1
194	C2
195	C3
196	C4
197	C5
198	C6
199	C7
200	C8
201	C9
202	CA
203	CB
204	CC
205	CD
206	CE
207	CF

D: 208-223
X: D0-DF
Dec	Hex
208	D0
209	D1
210	D2
211	D3
212	D4
213	D5
214	D6
215	D7
216	D8
217	D9
218	DA
219	DB
220	DC
221	DD
222	DE
223	DF

D: 224-239
X: E0-EF
Dec	Hex
224	E0
225	E1
226	E2
227	E3
228	E4
229	E5
230	E6
231	E7
232	E8
233	E9
234	EA
235	EB
236	EC
237	ED
238	EE
239	EF

D: 240-255
X: F0-FF
Dec	Hex
240	F0
241	F1
242	F2
243	F3
244	F4
245	F5
246	F6
247	F7
248	F8
249	F9
250	FA
251	FB
252	FC
253	FD
254	FE
255	FF

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();
}

Hexadecimal (Hex) to Decimal Lookup Table

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

Summary

Hex To Decimal Lookup Table

Why I Programmed a Hex to Dec Lookup Table?

C# Code to General Hex to Decimal Lookup Table

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