Depression Symptom Severity Calculator (PHQ-9 Based)
The Patient Health Questionnaire-9 (PHQ-9) is a validated, self-administered tool used to screen for and measure the severity of depression. Rate how often you have been bothered by each of the following problems over the past two weeks.
⚠️ Disclaimer: This tool is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. If you are experiencing thoughts of self-harm, please contact a mental health professional or call a crisis helpline immediately.
Rating Scale: 0 = Not at all | 1 = Several days | 2 = More than half the days | 3 = Nearly every day
Formula
PHQ-9 Total Score = Q1 + Q2 + Q3 + Q4 + Q5 + Q6 + Q7 + Q8 + Q9
Each of the 9 questions is scored on a 4-point Likert scale:
• 0 = Not at all
• 1 = Several days
• 2 = More than half the days
• 3 = Nearly every day
Total score range: 0–27
Severity Classification:
• 0–4: Minimal or No Depression — Watchful waiting; repeat PHQ-9 at follow-up
• 5–9: Mild Depression — Patient education, watchful waiting
• 10–14: Moderate Depression — Treatment plan, counseling, follow-up
• 15–19: Moderately Severe Depression — Active treatment with pharmacotherapy and/or psychotherapy
• 20–27: Severe Depression — Immediate pharmacotherapy; referral to mental health specialist
Note on Question 9: Any score ≥ 1 on Question 9 (thoughts of self-harm) requires immediate clinical attention regardless of total score.
Assumptions & References
- The PHQ-9 is a validated, self-report instrument derived from the Primary Care Evaluation of Mental Disorders (PRIME-MD) diagnostic instrument.
- Responses reflect symptom frequency over the past two weeks, consistent with DSM-5 criteria for major depressive episode duration.
- A PHQ-9 score ≥ 10 has a sensitivity of 88% and specificity of 88% for major depression (Kroenke et al., 2001).
- The tool screens for all nine DSM-5 criteria for major depressive disorder: anhedonia, depressed mood, sleep disturbance, fatigue, appetite changes, worthlessness/guilt, concentration difficulties, psychomotor changes, and suicidal ideation.
- This calculator does not replace clinical judgment. Diagnosis requires a comprehensive clinical evaluation by a qualified healthcare professional.
- Functional impairment (difficulty at work, home, or with others) is an additional clinical consideration not captured in the total score.
- References:
- Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606–613.
- Spitzer RL, Kroenke K, Williams JB. Validation and utility of a self-report version of PRIME-MD. JAMA. 1999;282(18):1737–1744.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5). 2013.
- Löwe B, et al. Comparative validity of three screening questionnaires for DSM-IV depressive disorders. J Affect Disord. 2004;78(2):131–140.