Zung Self-Rating Depression Scale

Evaluates depression symptoms to determine the severity of the depressive disorder the patient suffers from.

In the text below the calculator you can find more information on how the scale should be interpreted and a list of the main depression symptoms.

The Zung self-rating depression scale represents a self-administered questionnaire aimed at revealing the severity of the depressive disorder based on the frequency of the main depression signs and symptoms.

The Zung SDS has been validated in numerous studies and is recommended for monitoring purposes.

The numerical result obtained by summing the points from each item of the Zung SDS is interpreted as follows: 

Raw score (20 – 80) SDS Index (25 – 100) Interpretation
20 – 39 25 – 49 Normal range
40 – 47 50 – 59 Mild Depression
48 – 55 60 – 69 Moderate or marked depression
56 – 80 70 – 100 Severe depression

1I feel down-hearted and blue
2Morning is when I feel the best
3I have crying spells or feel like it
4I have trouble sleeping at night
5I eat as much as I used to
6I still enjoy sex
7I notice that I am losing weight
8I have trouble with constipation
9My heart beats faster than usual
10I get tired for no reason
11My mind is as clear as it used to be
12I find it easy to do the things I used to
13I am restless and can’t keep still
14I feel hopeful about the future
15I am more irritable than usual
16I find it easy to make decisions
17I feel that I am useful and needed
18My life is pretty full
19I feel that others would be better off if I were dead
20I still enjoy the things I used to do
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Zung depression scale explained

The Zung SDS is addressed to adult patients who suffer from depression symptoms. These are assessed on two sets of Likert scales. The scale was first published by Zung in 1965.

Some of the items in this self-report questionnaire are formulated in a positive manner whilst others are formulated in a negative manner, meaning that although the items in the Likert scale remain the same, their order and associated points change.

Items 1, 3, 4, 7, 8, 9, 10, 13, 15, 19 are scored:

■ A little of the time (1);

■ Some of the time (2);

■ Good part of the time (3);

■ Most of the time (4).

For items 2, 5, 6, 11, 12, 14, 16, 17, 18, 20 the scale is reversed as follows:

■ Most of the time (1);

■ Good part of the time (2);

■ Some of the time (3);

■ A little of the time (4).

The following table introduces the symptoms covered in the Zung SDS, which reflect four areas: pervasive effect, physiological equivalents, psychomotor activities and other disturbances:

Depressed mood;
Clouded reasoning;
Difficulty with completing tasks;
Difficult decision making;
Morning symptoms;
Lack of hope;
Diminished self esteem;
Suicidal ideation;
Diminished appetite;
Weight loss;
Sexual interest;

The Zung depression scale is recommended for clinical monitoring purposes and has been validated through several studies. For diagnosis of depression, other investigation methods should be employed.


Score interpretation

In this self-report questionnaire, each of the 20 items is awarded a number of points from 1 to 4, depending on the experienced frequency of the depression symptoms.

The overall score ranges from 20 to 80. In some clinical settings, this is reported as a SDS index, with values between 25 and 100.

The conversion to the SDS Index (the 100 point scale) follows the below equation:

SDS Index = Raw score x 1.25

The table below summarizes the score categories:

Raw score (20 – 80) SDS Index (25 – 100) Interpretation
20 – 39 25 – 49 Normal range
40 – 47 50 – 59 Mild Depression
48 – 55 60 – 69 Moderate or marked depression
56 – 80 70 – 100 Severe depression

Regardless of the reporting system, the higher the score, the more severe the depression symptoms.


Main depression symptoms

Depressive disorder is characterized by a variety of symptoms and not all cases display similar signs. Also, some case may display combinations of symptoms with other mental conditions, such as bipolar, anxiety or attention deficit disorders.

The main depression symptoms include:

■ Persistent sadness;

■ Feelings of hopelessness or guilt;

■ Irritability;

■ Excessive worrying;

■ Anxiousness;

■ Suicidal ideation;

■ Psychosomatic pain;

■ Eating or sexual behaviour disorders;

■ Insomnia;

■ Disruption of biological patterns.


Original source

Zung WW. A Self-Rating Depression Scale. Arch Gen Psychiatry. 1965; 12:63-70.


Zung WW, Richards CB, Short MJ. Self-rating depression scale in an outpatient clinic. Further validation of the SDS. Arch Gen Psychiatry. 1965; 13(6):508-15.

Other references

1. Biggs JT, Wylie LT, Ziegler VE. Validity of the Zung Self-rating Depression Scale. Br J Psychiatry. 1978; 132:381-5.

2. Carroll BJ, Fielding JM, Blashki TG. Depression rating scales. A critical review. Arch Gen Psychiatry. 1973; 28(3):361-6.

Specialty: Psychiatry

System: Nervous

Objective: Assessment

Type: Scale

No. Of Items: 20

Year Of Study: 1965

Article By: Denise Nedea

Published On: August 28, 2017 · 02:22 AM

Last Checked: August 28, 2017

Next Review: August 28, 2023