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Knowledge Article

Guide: Converting inches to mm

By Colly Flowtech

Inch to millimeter converter

Enter a value in inches (e.g. 1.5 or 1 1/2) or millimeters and the second unit will be calculated automatically.

Formula: 1 inch = 25.4 mm

How much is an inch?

One inch equals 25.4 millimeters.

What is an inch?

Inches are a unit of length used mainly in the US and UK. Many hoses/pipes indicate diameter in inches and therefore we have put together a table with inches to mm on the most common dimensions below so that you can easily find the dimension you need on your pipe or hose.

How do you convert inches to millimeters?

Since 1 inch is 25.4 mm, it is easy to work out how many millimeters a number is in inches by multiplying the number of inches by 25.4. For example, if you want to know what 3/8 inch to mm is, the formula is 3/8 inch = 0.375 inch x 25.4 mm = 9.525 mm.

If you have a number in mm and want to find out how much it is in inches, divide the millimeter number by 25.4 instead.

Conversion table inches to mm

TumTumMillimeter
1/640,016
0,397
1/32
0,031
0,794
3/64
0,047
1,191
1/16
0,063
1,588
5/64
0,078
1,984
3/32
0,094
2,381
7/64
0,109
2,778
1/8 
0,125
3,175
9/64
0,141
3,572
5/32
0,156
3,969
11/64
0,172
4,366
3/16
0,188
4,763
13/64
0,203
5,159
7/32
0,219
5,556
15/64
0,234
5,953
1/4
0,25
6,35
17/64
0,266
6,747
9/32
0,281
7,144
19/64
0,297
7,541
5/16
0,313
7,938
21/64
0,328
8,334
11/32
0,344
8,731
23/64
0,359
9,128
3/8
0,375
9,525
25/64
0,391
9,992
13/32
0,406
10,319
27/64
0,422
10,716
7/16
0,48
11,113
29/64
0,453
11,509
15/32
0,469
11,906
31/64
0,484
12,303
1/2
0,5
12,7
33/64
0,516
13,097
17/32
0,531
13,494
35/64
0,547
13,891
9/16
0,563
14,288
37/64
0,578
14,684
19/32
0,594
15,081
39/64
0,609
15,478
5/8
0,625
18,875
41/64
0,641
16,272
21/32
0,656
16,669
43/64
0,672
17,066
11/16
0,688
17,463
45/64
0,703
17,859
23/32
0,719
18,256
47/64
0,734
18,653
3/4
0,75
19,05
49/64
0,766
19,447
25/32
0,781
19,844
51/64
0,797
20,241
13/16
0,813
20,638
53/64
0,828
21,034
27/32
0,844
21,431
55/64
0,859
21,828
7/8
0,875
22,225
57/64
0,891
22,622
29/32
0,906
23,019
59/64
0,922
23,416
15/16
0,93823,813
61/64
0,953
24,209
31/32
0,969
24,606
63/64
0,984
25,003
1
1,0
25,4
1 1/4
1,25
31,75
1 1/2
1,5
38,1
1 3/4
1,75
44,45
2
2,0
50,8
2 1/2
2,5
63,5
3
3,0
76,2
3 1/2
3,5
88,9
4
4,0
101,9
4 1/2
4,5
114,3
5
5,0
127
6
6,0
152,4
7
7,0
177,8
8
8,0
203,2
9
9,0
228,6
10
10,0
254
11
11,0
279,4

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