Table 1.

Foot length measurement methods

Measurement tools
Firm ruler (plastic, metal, wooden) (See online supplemental WebAppendix 7a)	Firm; low cost and locally accessible; does not required specialised tool or procurement.
Sliding callipers	Precise however requires specialised tool, more costly and difficult to procurethan ruler.
Flexible measuring tape	Low cost, locally available. Flexible tape is not fixed or firm; may be less reliable and prone to variation between measurements.
Footprint (See online supplemental WebAppendix 4a: eFigure 1)	Requires firm surface. Can be measured retrospectively. Challenges include local/cultural beliefs regarding foot/finger prints and requires cleaning foot afterwards.
Foot length measuring board (See online supplemental WebAppendix 7b)	Precise, reliable; however, requires specialised tool that maybe difficult to manufacture or procure.
Measurement Techniques/Axis
Heel-to-hallux	Linear distance measured from the base of the heel to the tip of hallux (big toe)
Heel-to-longest toe	Linear distance measured from the base of the heel to the tip of the longest toe (first, second, or third digit)
Vertical distance	Linear distance measured from the base of the heel to longest digit, along vertical axis of foot