Directions for scoring are included in chapter 6 of the manual, which is available on the WHO website at: https://bit.ly/2IOQpeh

There are two options for computing the summary scores for the WHODAS 2.0 short and full versions.
Simple: the scores assigned to each of the items – 'none' (0), 'mild' (1) 'moderate' (2), 'severe' (3) and 'extreme' (4) – are summed. This method is referred to as simple scoring because the scores from each of the items are simply added up without recoding or collapsing of response categories; thus, there is no weighting of individual items. This approach is practical to use as a hand-scoring approach, and may be the method of choice in busy clinical settings or in paper–pencil interview situations. As a result, the simple sum of the scores of the items across all domains constitutes a statistic that is sufficient to describe the degree of functional limitations.

Scoring sheets in excel are available at: https://www.who.int/classifications/icf/whodasii/en/
12-item Instrument Scoring Sheet
36-item Instrument Scoring Sheet, Simple Scoring Calculation
36-item Instrument Scoring Sheet, Domain-Weighted Scoring Calculation

The more complex method of scoring is called 'item-response-theory' (IRT) based scoring. It takes into account multiple levels of difficulty for each WHODAS 2.0 item. It takes the coding for each item response as 'none', 'mild', 'moderate', 'severe' and 'extreme' separately, and then uses an algorithm to determine the summary score by differentially weighting the items and the levels of severity. The scoring has three steps:

Step 1 – Summing of recoded item scores within each domain.
Step 2 – Summing of all six domain scores.
Step 3 – Converting the summary score into a metric ranging from 0 to 100 (where 0 = no disability; 100 = full disability).

The SPSS algorithm is available from WHO. Contact whodas@who.int.

Please note that the question responses for WHODAS 2.0 have not changed (No Difficulty, Mild Difficulty, Moderate Difficulty, Severe Difficulty, and Extreme Difficulty or Cannot Do), but the numbers assigned to them have (using a 5 point scale from 0-4 rather than from 1-5). This is in response to feedback received and will not change the final score if you use the correct scale for the correct method. Use the 0-4 scale for these templates, only.