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UNICEF Innovation

Weight Estimation Tapes

In emergencies or low-resource settings, however, measuring weight with calibrated scales may be impossible or impractical. The Childrens Mercy Hospital in the USA has developed a solution that UNICEF has been authorized to use in developing countries.



The Mercy Children's Hospital in Missouri, USA has designed and validated “The Mercy Method” for weighing infants. It utilizes 2 new devices,  2D and 3D Mercy Tapes, to estimate weight by using surrogates of both height (humeral length) and girth (mid-upper arm circumference). The method does not require body length (which may be difficult to obtain in uncooperative or combative children) or age (which may be unavailable), and can be applied to children aged 2 months through 16 years. Both Mercy Tapes have been validated for accuracy in Africa, Asia and the United States across extremes of weights.


The Mercy Children's Hospital has authorized UNICEF to use, in an unrestricted manner, the patent of the Mercy Tape in developing countries. The purpose of this project is to address the challenge that remains, which is developing and testing the Mercy Tape for optimal use in the field. To obtain the optimal Mercy Tape design and to provide the necessary user guidelines, a field study will take place with the cooperation of community health workers (CHWs). Use acceptability amongst CHWs will be recorded and evaluated to identify how the tape, and accompanying user training needs, can be improved



From 7th-19th October, 2014, the formal launch of the field trials and the training of trainers in Benin and Democratic Republic of Congo were carried out. The objectives of the field trials were threefold:

  • To evaluate the usability of the Weight Measurement Tapes
  • To assess the likability of the product
  • To observe potential applications of the product

The Democratic Republic of Congo was the first UNICEF country offices to enrol in the field trial. Not less than 2000 children’s weight were estimated by the Weight Measurement Tapes. The data collection took place in ten locations in Kinshasa.

Child being measured by the tape in DRC 

©UNICEF DRC/2014/Loic Sanchez 

In Benin, 2600 children’s weights were estimated using the measurement tapes. The data collection was carried out in several healthcare centres and hospitals around Cotonou. In both countries, healthcare workers were asked to use the 2D and 3D version of the tape to see which one was the most user friendly. The findings of the field trip will shortly be communicated on the website. 



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