Enter the Crown-Rump Length into the calculator to determine the Nuchal Fold Thickness.

Nuchal Fold Formula

The following formula is used to calculate the Nuchal Fold Thickness (NFT) in millimeters.

NFT = (CRL * 0.1) + 0.9


  • NFT is the Nuchal Fold Thickness (mm) CRL is the Crown-Rump Length (mm)

To calculate the Nuchal Fold Thickness, multiply the Crown-Rump Length by 0.1, then add 0.9 to the result. This formula is based on the average Nuchal Fold Thickness for a given Crown-Rump Length.

What is a Nuchal Fold?

A nuchal fold is a layer of fluid at the back of a fetus’s neck that can be measured during an ultrasound scan, typically between the 11th and 14th week of pregnancy. This measurement can help doctors assess the risk of certain genetic disorders, such as Down syndrome, as a thicker nuchal fold can be a potential indicator of these conditions. However, it is not a definitive diagnostic tool and further tests may be required for a confirmed diagnosis.