SDS: Zung Self-Rating Depression Scale

What is SDS?

SDS (Zung Self-Rating Depression Scale) is a validated clinical instrument used to assess 20-item self-report scale measuring affective, psychological, and somatic symptoms of depression.. It is most often used for 20-item self-report scale measuring affective, psychological, and somatic symptoms of depression.. The instrument contains 20 items. Typical administration time is ≈ 5 min.

Source / attribution: Free to use with citation

Clinical context: when SDS is used

20-item self-report scale measuring affective, psychological, and somatic symptoms of depression. SDS is part of standard practice in this setting because it provides a structured, replicable assessment that can be tracked over time and compared across patients or visits.

Like all screening or assessment instruments, SDS is a structured aid — not a diagnostic test in isolation. Results should be interpreted alongside history, examination, and clinical context. Where a score crosses an actionable threshold, the next step is typically a more detailed clinical evaluation rather than a definitive diagnosis.

Score SDS

Each item is scored on a 4-point scale (1–4). Your score updates live as you answer.

All scoring runs in your browser. No data is sent anywhere — close the tab and the answers are gone.

How SDS is scored

Sum raw scores, multiply by 1.25 to get index score (25-100). Index < 50 = normal, 50-59 = mild, 60-69 = moderate, >= 70 = severe.

Scoring notes: Sum raw scores, multiply by 1.25 to get index score (25-100). Index < 50 = normal, 50-59 = mild, 60-69 = moderate, >= 70 = severe.

SDS score interpretation

The cutoffs below are drawn from the published validation literature. Always interpret in clinical context.

How to score SDS: a step-by-step worked example

This is an illustrative walkthrough, not a real patient. Follow the same four steps with your own answers — or use the live calculator at the top of this page.

Step 1 — Score each item

Read each question and choose the response that best fits. Each response has a number next to it — that number is the item's score. The example below uses illustrative answers.

Step 2 — Add up the scores

Add up all the item scores you noted in Step 1.

3 + 3 + 3 + 3 + 3 + 3 + 3 + 3 + … (items 9–20 sum to 31) = 55

Step 3 — Look up the band

Find the row in the interpretation table whose range contains your total:

Total = 55 falls between 50 and 59 → Mild depression

Step 4 — What does this mean clinically?

Mild depression. Monitor

A score is one input alongside history and examination. SDS supports clinical judgment — it does not replace it.

Score SDS with your own answers above →

SDS psychometric properties

• Internal consistency. Cronbach's α = 0.81 — acceptable to good.
• Test–retest reliability. r = 0.7 — stable across repeated administrations.
• Validity. Widely validated across cultures and clinical settings.

Psychometric figures are drawn from the validation literature and may vary across clinical populations and translations.

Limitations & common pitfalls

• Sum raw scores, multiply by 1.25 to get index score (25-100). Index < 50 = normal, 50-59 = mild, 60-69 = moderate, >= 70 = severe.
• Screening, not diagnosis. A positive SDS score is not equivalent to a diagnosis. Confirmatory clinical evaluation is required before treatment decisions.
• Population calibration. Cutoffs were derived from specific validation populations. Performance can differ in other age groups, languages, comorbid conditions, or clinical settings.
• Self-report bias. Patient-reported instruments are subject to under- and over-reporting; clinical context is essential.

How SDS compares to other depression scales

If SDS doesn't fit your context, related instruments in depression include:

Frequently asked questions about SDS

References & validation

SDS is supported by the following peer-reviewed sources:

• Zung, W. W. (1965). A self-rating depression scale. Archives of General Psychiatry, 12(1), 63-70. doi:10.1001/archpsyc.1965.01720310065008 · PubMed