Neck Disability Index Calculator

How it is calculated

Each answered section of the questionnaire is scored 0 to 5, so the highest possible raw score is max = sections × 5. The index is the share of that maximum: NDI % = raw / (sections × 5) × 100, rounded to one decimal. The sections field defaults to 10, the full questionnaire; enter a smaller whole number (1 to 9) if a section was skipped as not applicable, so the percentage is not dragged down. The raw score must be between 0 and the maximum, and sections must be a whole number from 1 to 10, otherwise there is no result. The category is read from the rounded percentage: up to 8 is none or minimal, up to 28 mild, up to 48 moderate, up to 68 severe, and above 68 complete disability. The tool also prints the score as raw / maximum, for example 18 / 50, and a note that it is for education only.

Common mistakes

• Entering the percentage as the raw score. The first field is the sum of section scores (0 to 50), not an already-converted percentage.
• Leaving the sections at 10 when a section was skipped. The maximum then stays at 50 and the percentage is understated; enter 9 for nine answered sections.
• Adding up scores from a version of the questionnaire that uses a different scale, such as 0 to 4 per section. This tool assumes 0 to 5 per section.
• Entering more than 10 sections or a fractional number. The standard form has 10 sections, and anything above that, or not a whole number, shows no result.
• Treating a single score as a diagnosis. The category only describes the questionnaire result, and changes are tracked by repeating it at follow-up visits. A score of exactly 28% still counts as mild, and 28.1% as moderate.