What is the NEX measurement?

NEX stands for Nose-Earlobe-Xiphisternum. You hold the tube tip at the patient's earlobe, measure to the tip of the nose, then to the xiphisternum, and the summed distance is used as the insertion length. It is the most common bedside method and the tool simply records the distance you measured.

What is the height-based formula?

Studies of adult NG tube placement suggest an insertion length of roughly the patient's height in centimetres multiplied by 0.25 and then adding around 6.5 centimetres reaches the stomach more reliably than NEX in some patients. The tool offers this as an alternative estimate; local policy decides which method is used.

Does this confirm correct placement?

No. It only estimates where to mark the tube before insertion. Correct gastric placement must be confirmed before any feed or medication, using aspirate pH of 5.5 or below as the first-line test and a chest X-ray if pH is inconclusive or the patient is at high risk.

Why can NEX underestimate the length?

The NEX route follows external landmarks that fall short of the actual nasogastric path in some adults, which can leave the tube tip in the oesophagus. That is why height-based formulas were developed and why radiological or pH confirmation is always mandatory rather than optional.

Can I use this for children?

No. Paediatric NG tube lengths use age- and length-specific charts such as the ARHB (age-related height-based) method, which differ from adult estimates. This tool is intended for adult patients only and should not be applied to children.

Nasogastric Tube Insertion Length Estimator

A nasogastric tube is marked to an estimated insertion depth before placement, then confirmed by aspirate pH and X-ray. This tool gives that starting estimate either from a NEX (Nose-Earlobe-Xiphisternum) measurement you have taken at the bedside or from the patient’s height.

How it works

Two methods are offered for adults:

NEX method:    insertion length = the nose-earlobe-xiphisternum distance you measured

Height-based:  insertion length (cm) = height (cm) × 0.25 + 6.5

The NEX route uses external landmarks and is quick, but it can fall short of the true path in some adults, which is why a height-based formula is offered as an alternative. Whichever you use, the result is only a starting mark, never a confirmation of placement.

Example and notes

For a patient 170 cm tall, the height-based estimate is 170 × 0.25 + 6.5 ≈ 49 cm. A NEX measurement on the same patient might read 55 cm. These are starting marks only: aspirate pH of 5.5 or below confirms gastric placement first-line, and a chest X-ray is used when pH is inconclusive or the patient is high-risk. Never feed or give medication through the tube until placement is confirmed, and do not use this adult tool for children.