Rothwell scale

The Rothwell scale, or Rothwell system, or Rothwell method, applied to incontinence care products, is a scale that shows how absorbent a particular incontinence pad or adult diaper is, and how much liquid it can absorb and hold before it is likely to leak due to overfill.

The system provides a quick reference for assessing how much liquid can be held by a sheet, pad or diaper, and therefore how appropriate it will be for a particular individual in any given circumstance. The scale is based on the total absorbency test ISO 11948–1. The scale runs from 1 to 22, with 1 indicating the least liquid absorbed, measured in grams, and 22 the most liquid absorbed. The scale also applies a prefix to show what type of product is being referred to, with pads and sheets having an “I” prefix, and all in one diapers using a D prefix.

Scale	Absorbency		Scale	Absorbency
I1	0g to 49g		D14	1300g to 1699g
I2	50g to 99g		D15	1700g to 2099g
I3	100g to 199g		D16	2100g to 2499g
I4	200g to 299g		D17	2500g to 2899g
I5	300g to 449g		D18	2900g to 3299g
I6	450g to 599g		D19	3300g to 3699g
I7	600g to 799g		D20	3700g to 4099g
I8	800g to 999g		D21	4100g to 4499g
I9	1000g to 1249g		D22	4500g to 4899g
I10	1250g to 1499g
I11	1500g to 1799g
I12	1800g to 2099g
I13	2100g to 2499g
I14	2500g to 2899g
I15	2900g to 3299g

References

• M Fader, A Cottenden, K Getliffe, H Gage, S Clarke-O’Neill, K Jamieson, N Green, P Williams, R Brooks and J Malone-Lee, "Absorbent products for urinary/faecal incontinence: a comparative evaluation of key product designs", Health Technology Assessment, vol. 12, no. 29, 2008.
• A.M Cottenden, J.G Rothwell, H Leander, C Grau, R.J Brooks, "An investigation of the repeatability and reproducibility of ISO 11948-1 (the Rothwell method) for measuring the absorption capacity of incontinence pads", Medical Engineering & Physics, vol. 24, iss. 2, pp. 159–163, March 2002.
• ISO 11948-1:1996, "Urine-absorbing aids -- Part 1: Whole-product testing", International Organization for Standardization, 1996