PHQ-9 Depression Scale

The PHQ-9 is the most widely used depression screening tool in primary care worldwide — nine questions, each mapped directly to a DSM criterion for major depressive disorder, completed in a few minutes. This calculator scores the standard questionnaire and explains what the result typically means, including why one specific question is handled differently from the rest.

What the PHQ-9 measures

The PHQ-9 (Patient Health Questionnaire-9) was developed by Kroenke, Spitzer, and Williams, and published in 2001 in the Journal of General Internal Medicine. Each of its nine items corresponds directly to one of the diagnostic criteria for major depressive disorder: anhedonia (loss of interest or pleasure), depressed mood, sleep disturbance, fatigue, appetite change, feelings of worthlessness or guilt, concentration difficulty, psychomotor changes (moving or speaking noticeably slower or more restlessly than usual), and thoughts of death or self-harm. Each is rated by how often it occurred over the past two weeks, giving a consistent, standardized snapshot of symptom frequency.

This one-to-one mapping between questionnaire items and diagnostic criteria is a deliberate design choice, distinguishing the PHQ-9 from some other depression scales that measure related but less directly diagnostic constructs. Because each item tracks a specific DSM criterion, the PHQ-9 doubles as both a severity measure (via the total score) and a rough proxy for diagnostic criteria coverage (how many of the nine core symptoms are present at a clinically meaningful frequency) — a dual function that’s part of why it’s remained the standard screening tool across primary care, psychiatry, and research for over two decades.

How scoring works

The straightforward summing makes this instrument fast to score by hand or automatically, which is part of why it’s become so embedded in routine primary care workflows and electronic health records — a clinician or patient can complete and interpret it in the time it takes to check in for an appointment.

Worked example

Consider someone reporting: little interest in activities “more than half the days” (2), feeling down “several days” (1), sleep trouble “nearly every day” (3), fatigue “more than half the days” (2), appetite changes “not at all” (0), feelings of worthlessness “several days” (1), concentration trouble “several days” (1), psychomotor changes “not at all” (0), and no thoughts of self-harm “not at all” (0):

A score of 10 sits right at the standard clinical cutoff — the point where a treatment plan (counseling, further evaluation, or both) is generally recommended rather than continued watchful waiting.

What the severity categories mean

These five bands come directly from the original validation study and remain the standard reference used in clinical practice today. At the ≥10 cutoff, the original research found 88% sensitivity and 88% specificity against a structured clinical interview — meaning it correctly identified about 88% of people who did have major depressive disorder, and correctly ruled out about 88% of people who didn’t.

The PHQ-9’s five-tier severity system is notably more granular than some comparable screening tools, which often use just three or four bands. This extra granularity — particularly the distinction between “moderately severe” (15–19) and “severe” (20–27) — gives clinicians a more precise way to calibrate treatment intensity and monitor whether a specific intervention is producing meaningful change over time, rather than only tracking whether someone has crossed a single binary threshold.

Why question 9 is treated differently

Question 9 asks about thoughts of being better off dead or of self-harm — and current clinical guidance is unambiguous that any response other than “not at all” warrants immediate attention, regardless of what the total score ends up being. A low total score with a positive answer to this one item is still clinically significant; it isn’t something that gets “averaged out” by otherwise-mild answers elsewhere in the questionnaire, and treating it that way would miss exactly the signal this item exists to catch.

This calculator reflects that distinction directly: answering question 9 with anything other than “not at all” shows a dedicated notice immediately, as soon as that question is answered — not only after the full questionnaire is completed and scored. This mirrors standard clinical practice, where this specific item is reviewed individually by a clinician rather than folded anonymously into the total.

This design reflects something important about how depression screening works in practice: the total score and question 9 are answering genuinely different questions. The total score describes overall symptom burden — how much someone is currently struggling across the full range of depressive symptoms. Question 9 asks something more specific and more urgent: whether thoughts of death or self-harm are present at all, a signal that research consistently shows can appear even when overall symptom burden looks comparatively mild on paper. Treating these as two separate signals, rather than compressing everything into one number, is exactly what current clinical guidance calls for, and exactly what this calculator is built to do.

What a score does — and doesn't — mean

A PHQ-9 score, however high, is not itself a diagnosis of major depressive disorder. A full diagnosis requires a clinical evaluation confirming that a sufficient number of these symptoms have been present for at least two consecutive weeks, represent a change from previous functioning, and cause meaningful distress or impairment in daily life — criteria a self-administered questionnaire alone can flag but can’t fully confirm. Some clinical versions of the PHQ-9 include a supplementary question (sometimes called item 10) asking how difficult these symptoms have made it to work, manage things at home, or get along with others — this doesn’t count toward the 0–27 score but adds useful context about functional impact, which many self-screening tools (including this one) omit for simplicity while the core 9-item score remains the same either way.

A high score is best understood as a strong, evidence-based signal that a fuller evaluation is worthwhile — not a verdict. Many things that produce a PHQ-9 profile resembling depression have other explanations entirely: thyroid conditions, certain medications, grief following a genuine loss, sleep disorders, and other physical health conditions can all produce overlapping symptoms. A doctor is positioned to consider and rule out these alternative explanations in a way a questionnaire cannot, which is exactly why an elevated score is framed here as a prompt to seek evaluation rather than a conclusion in itself.

Grief deserves a specific mention here, since it’s one of the more common reasons a PHQ-9 score can look elevated without necessarily reflecting major depressive disorder. Grief after a genuine loss can produce many of the same symptoms this questionnaire measures — low mood, poor sleep, appetite changes, difficulty concentrating — and current diagnostic guidance has moved away from automatically excluding grief-related symptoms from a depression diagnosis, recognizing that grief and depression can also co-occur or that grief can, in some cases, become genuinely complicated. This is exactly the kind of nuanced distinction that benefits from a clinician’s judgment rather than a questionnaire score interpreted in isolation.

Depression is treatable

It’s worth stating plainly: major depressive disorder is one of the more treatable mental health conditions, with strong research support behind multiple effective approaches. Cognitive behavioral therapy and interpersonal therapy both have substantial evidence behind them, several classes of antidepressant medication have well-established track records, and many people see meaningful improvement combining therapy and medication together. A moderate or severe PHQ-9 score is the kind of result that, brought to the right professional, commonly leads to real improvement — not a permanent state to simply manage indefinitely.

Response to treatment is also something the PHQ-9 itself is well-suited to help track, which is part of why it’s re-administered periodically rather than used only once. A common benchmark clinicians look for is at least a 50% reduction in total score after an adequate trial of treatment (typically 6-8 weeks for medication to show full effect), with the goal being not just improvement but genuine remission — a score back down in the minimal range, not just a reduction from a starting point of severe symptoms to moderate ones. Tracking this trajectory over successive administrations gives both patient and provider a concrete, numeric way to evaluate whether a given treatment approach is working, rather than relying on subjective impression alone.

Using this tool responsibly

This calculator is genuinely useful for getting a preliminary sense of whether current symptoms fall in a range worth discussing with a doctor, for tracking personal symptom trends between appointments (the PHQ-9 is commonly re-administered every 2–4 weeks during treatment specifically to monitor whether it’s working), or for putting a name to a cluster of experiences that can otherwise feel diffuse and hard to describe out loud. It doesn’t replace professional evaluation, and any score worth a second look — particularly anything in the moderate range or higher, or any positive response to question 9 — is a reasonable, common reason to reach out, not something to sit with alone.

Reaching out is also more common than it might feel in the moment. Depression affects a substantial share of adults at some point in their lives, and primary care visits specifically for mood-related concerns are routine, well-understood parts of what doctors handle regularly — not an unusual or awkward request. Framing a conversation with a doctor as simply “I filled out a screening questionnaire and wanted to talk about the result” is a completely normal, low-friction way to start that conversation.

If you’re in crisis right now, or having thoughts of harming yourself, support is available immediately: call or text 988 (the Suicide & Crisis Lifeline) or text HOME to 741741 (Crisis Text Line), both free, confidential, and available 24/7. For depression symptoms that aren’t a crisis but feel like more than you want to carry alone, a primary care doctor is often the most straightforward starting point — they can evaluate directly and refer to a therapist or psychiatrist as needed, without requiring you to first work out exactly what kind of specialist is right.