Millimeters (mm) to Inches (in) Converter

This length unit converter dynamically calculates a value you enter in millimeters (mm) and converts it to its equivalent value in inches (in).

Convert millimeters to other units of length:

➞ browse complete list of length unit converters
➞ go to Unit Converters & Calculators homepage

How many millimeters (mm) are in an inch (in)? What is the formula for how to convert millimeters to inches (mm to in)?

1 millimeter (mm) = 0.039370078740157 inch (in)
So we can say that there is 0.039370078740157 inch in 1 millimeter.
This means that the multiplication conversion factor to convert a quantity expressed in a millimeter unit of measurement to an equivalent quantity expressed in an inch unit of measurement is 0.039370078740157.

Inversely (or reciprocally),

1 inch (in) = 25.4 millimeters (mm)
So we can say that there is 25.4 millimeters in 1 inch.
This means that the division conversion factor to convert a quantity expressed in a millimeter unit of measurement to an equivalent quantity expressed in an inch unit of measurement is 25.4.

Knowing this inverse mathematical relationship between the two conversion factors and their reciprocal operations, we can derive two formulas to calculate and convert a quantity of length expressed in millimeters to an equivalent quantity of length expressed in inches (mm to in). Both formulas will yield the same result. The formulas are:

in = mm × 0.039370078740157    → This is the formula based on the multiplication conversion factor.

and

in = mm ÷ 25.4    → This is the formula based on the division conversion factor.

For example, if you have a length of 250 millimeters that you want to convert to inches, you would use either of the two formulas as follows:

in = 250 mm × 0.039370078740157 = 9.842519685 in

in = 250 mm ÷ 25.4 = 9.842519685 in

So, the result is the same using either formula, which is 9.842519685 inches.

Millimeters to inches (mm to in) conversion chart

To save you time and effort spent on having to perform manual calculations or look up conversion formulas every time a conversion from millimeters to inches is needed, here is a millimeters-to-inches conversion chart for your quick and easy reference. This conversion chart (or conversion table) shows common measurement values of length in millimeters and their equivalent measurement values in inches. These equivalent measurement values may be rounded off to 1 or 2 decimal places when it is mathematically expedient for everyday applications.

millimeters (mm)	inches (in)
1 mm	0.04 in
2 mm	0.08 in
3 mm	0.12 in
4 mm	0.16 in
5 mm	0.20 in
6 mm	0.24 in
7 mm	0.28 in
8 mm	0.31 in
9 mm	0.35 in
10 mm	0.39 in
11 mm	0.43 in
12 mm	0.47 in
13 mm	0.51 in
14 mm	0.55 in
15 mm	0.59 in
16 mm	0.63 in
17 mm	0.67 in
18 mm	0.71 in
19 mm	0.75 in
20 mm	0.79 in
21 mm	0.83 in
22 mm	0.87 in
23 mm	0.91 in
24 mm	0.94 in
25 mm	0.98 in
26 mm	1.02 in
27 mm	1.06 in
28 mm	1.10 in
29 mm	1.14 in
30 mm	1.18 in
31 mm	1.22 in
32 mm	1.26 in
33 mm	1.30 in
34 mm	1.34 in
35 mm	1.38 in
36 mm	1.42 in
37 mm	1.46 in
38 mm	1.50 in
39 mm	1.54 in
40 mm	1.57 in
41 mm	1.61 in
42 mm	1.65 in
43 mm	1.69 in
44 mm	1.73 in
45 mm	1.77 in
46 mm	1.81 in
47 mm	1.85 in
48 mm	1.89 in
49 mm	1.93 in
50 mm	1.97 in
51 mm	2.01 in
52 mm	2.05 in
53 mm	2.09 in
54 mm	2.13 in
55 mm	2.17 in
56 mm	2.20 in
57 mm	2.24 in
58 mm	2.28 in
59 mm	2.32 in
60 mm	2.36 in
61 mm	2.40 in
62 mm	2.44 in
63 mm	2.48 in
64 mm	2.52 in
65 mm	2.56 in
66 mm	2.60 in
67 mm	2.64 in
68 mm	2.68 in
69 mm	2.72 in
70 mm	2.76 in
71 mm	2.80 in
72 mm	2.83 in
73 mm	2.87 in
74 mm	2.91 in
75 mm	2.95 in
76 mm	2.99 in
77 mm	3.03 in
78 mm	3.07 in
79 mm	3.11 in
80 mm	3.15 in
81 mm	3.19 in
82 mm	3.23 in
83 mm	3.27 in
84 mm	3.31 in
85 mm	3.35 in
86 mm	3.39 in
87 mm	3.43 in
88 mm	3.46 in
89 mm	3.50 in
90 mm	3.54 in
91 mm	3.58 in
92 mm	3.62 in
93 mm	3.66 in
94 mm	3.70 in
95 mm	3.74 in
96 mm	3.78 in
97 mm	3.82 in
98 mm	3.86 in
99 mm	3.90 in
100 mm	3.94 in

millimeters (mm)	inches (in)
101 mm	3.98 in
102 mm	4.02 in
103 mm	4.06 in
104 mm	4.09 in
105 mm	4.13 in
106 mm	4.17 in
107 mm	4.21 in
108 mm	4.25 in
109 mm	4.29 in
110 mm	4.33 in
111 mm	4.37 in
112 mm	4.41 in
113 mm	4.45 in
114 mm	4.49 in
115 mm	4.53 in
116 mm	4.57 in
117 mm	4.61 in
118 mm	4.65 in
119 mm	4.69 in
120 mm	4.72 in
121 mm	4.76 in
122 mm	4.80 in
123 mm	4.84 in
124 mm	4.88 in
125 mm	4.92 in
126 mm	4.96 in
127 mm	5.00 in
128 mm	5.04 in
129 mm	5.08 in
130 mm	5.12 in
131 mm	5.16 in
132 mm	5.20 in
133 mm	5.24 in
134 mm	5.28 in
135 mm	5.31 in
136 mm	5.35 in
137 mm	5.39 in
138 mm	5.43 in
139 mm	5.47 in
140 mm	5.51 in
141 mm	5.55 in
142 mm	5.59 in
143 mm	5.63 in
144 mm	5.67 in
145 mm	5.71 in
146 mm	5.75 in
147 mm	5.79 in
148 mm	5.83 in
149 mm	5.87 in
150 mm	5.91 in
151 mm	5.94 in
152 mm	5.98 in
153 mm	6.02 in
154 mm	6.06 in
155 mm	6.10 in
156 mm	6.14 in
157 mm	6.18 in
158 mm	6.22 in
159 mm	6.26 in
160 mm	6.30 in
161 mm	6.34 in
162 mm	6.38 in
163 mm	6.42 in
164 mm	6.46 in
165 mm	6.50 in
166 mm	6.54 in
167 mm	6.57 in
168 mm	6.61 in
169 mm	6.65 in
170 mm	6.69 in
171 mm	6.73 in
172 mm	6.77 in
173 mm	6.81 in
174 mm	6.85 in
175 mm	6.89 in
176 mm	6.93 in
177 mm	6.97 in
178 mm	7.01 in
179 mm	7.05 in
180 mm	7.09 in
181 mm	7.13 in
182 mm	7.17 in
183 mm	7.20 in
184 mm	7.24 in
185 mm	7.28 in
186 mm	7.32 in
187 mm	7.36 in
188 mm	7.40 in
189 mm	7.44 in
190 mm	7.48 in
191 mm	7.52 in
192 mm	7.56 in
193 mm	7.60 in
194 mm	7.64 in
195 mm	7.68 in
196 mm	7.72 in
197 mm	7.76 in
198 mm	7.80 in
199 mm	7.83 in
200 mm	7.87 in

Conversion of 1 millimeter (mm) to other units of length

Here is a reference list providing a conversion of 1 millimeter (mm) to its equivalent values in various units of length, both metric and imperial:

1 millimeter (mm) = 1,000,000 nanometers (nm)
1 millimeter (mm) = 1,000 micrometers (µm)
1 millimeter (mm) = 0.1 centimeter (cm)
1 millimeter (mm) = 0.01 decimeter (dm)
1 millimeter (mm) = 0.001 meter (m)
1 millimeter (mm) = 0.000001 kilometer (km)
1 millimeter (mm) = 0.039370078740157 inch (in)
1 millimeter (mm) = 0.0032808398950131 foot (ft)
1 millimeter (mm) = 0.0010936132983377 yard (yd)
1 millimeter (mm) = 0.00000062137119223733 mile (mi)
1 millimeter (mm) = 0.00000053995680345572 nautical mile (nmi)

What is a millimeter (mm)?

Definition of millimeter: A millimeter is a unit of length in the International System of Units (SI). It is equivalent to one thousandth of a meter (10^-3 m). It is commonly used for precisely measuring small lengths and dimensions such as mechanical parts in engineering and manufacturing.

The abbreviation for millimeter is mm. The single Unicode character ㎜ (U+339C) represents the 2-character Latin abbreviation for millimeter. The Windows Alt code for this character ㎜ is Alt + 13212.

What is an inch (in)?

Definition of inch: An inch is an imperial and US customary unit of length equal to 1/12 of a foot or 2.54 centimeters. It is often used in the United States and the United Kingdom, that follow these measurement systems for small measurements such as in construction and carpentry.

The abbreviation for inch is in. The single Unicode character ㏌ (U+33CC) represents the 2-character Latin abbreviation for inch. The Windows Alt code for this character ㏌ is Alt + 13260.

The informal symbol for inch is represented by a double prime (″) or double quote (“). For example, 12 inches can be written as 12″.