Crown Rump Length Chart: Fetal Ultrasound Measurements
Prenatal Testing
Obie Editorial Team
The fetal crown-rump length (CRL) is defined as the longest length of the fetus excluding the limbs and yolk sac. It is the measurement between the top of the head to the area above where the legs begin.
The fetal crown-rump length is taken via ultrasound usually up to the 14th week of the pregnancy.
This chart shows approximate crown-rump lengths according to days of fertilization and the last menstrual period.
Check out our comprehensive ultrasound guide!
Days (LMP) | Days (Fertilization) | (weeks/days) | (mm) |
37 | 23 | 5.2 | 1 |
38 | 24 | 5.3 | 2 |
39 | 25 | 5.4 | 3 |
40 | 26 | 5.5 | 3 |
41 | 27 | 5.6 | 4 |
42 | 28 | 6 | 4 |
43 | 29 | 6.1 | 5 |
44 | 30 | 6.2 | 6 |
45 | 31 | 6.3 | 7 |
46 | 32 | 6.4 | 8 |
47 | 33 | 6.5 | 9 |
48 | 34 | 6.6 | 10 |
49 | 35 | 7 | 11 |
50 | 36 | 7.1 | 11 |
51 | 37 | 7.2 | 12 |
52 | 38 | 7.3 | 12 |
53 | 39 | 7.4 | 13 |
54 | 40 | 7.5 | 14 |
55 | 41 | 7.6 | 15 |
56 | 42 | 8 | 17 |
57 | 43 | 8.1 | 18 |
58 | 44 | 8.2 | 19 |
59 | 45 | 8.3 | 20 |
60 | 46 | 8.4 | 21 |
61 | 47 | 8.5 | 22 |
62 | 48 | 8.6 | 22 |
63 | 49 | 9 | 23 |
64 | 50 | 9.1 | 24 |
65 | 51 | 9.2 | 26 |
66 | 52 | 9.3 | 27 |
67 | 53 | 9.4 | 28 |
68 | 54 | 9.5 | 29 |
69 | 55 | 9.6 | 31 |
70 | 56 | 10 | 34 |
71 | 57 | 10.1 | 36 |
72 | 58 | 10.2 | 37 |
73 | 59 | 10.3 | 38 |
74 | 60 | 10.4 | 39 |
75 | 61 | 10.5 | 39 |
76 | 62 | 10.6 | 40 |
77 | 63 | 11 | 44 |
78 | 64 | 11.1 | 45 |
79 | 65 | 11.2 | 47 |
80 | 66 | 11.3 | 48 |
81 | 67 | 11.4 | 52 |
82 | 68 | 11.5 | 55 |
83 | 69 | 11.6 | 56 |
84 | 70 | 12 | 57 |
85 | 71 | 12.1 | 58 |
86 | 72 | 12.2 | 60 |
87 | 73 | 12.3 | 61 |
88 | 74 | 12.4 | 63 |
89 | 75 | 12.5 | 64 |
90 | 76 | 12.6 | 65 |
91 | 77 | 13 | 68 |
92 | 78 | 13.1 | 70 |
93 | 79 | 13.2 | 72 |
94 | 80 | 13.3 | 74 |
95 | 81 | 13.4 | 76 |
96 | 82 | 13.5 | 77 |
97 | 83 | 13.6 | 80 |
98 | 84 | 14 | 81 |
99 | 85 | 14.1 | 84 |
100 | 86 | 14.2 | 85 |
101 | 87 | 14.3 | 86 |
102 | 88 | 14.4 | 87 |
Read More
Calculate ultrasound measurements and what they mean
The fetal head circumference or HC measures the circumference of the fetus' head. This calculator shows if your baby's head circumference is growing and progressing at a healthy rate. The head circumference is usually done after 13 weeks of the pregnancy.