It is one of the first questions almost everyone asks before starting therapy, and it is a reasonable thing to want a real answer to. Therapy is a financial commitment as well as an emotional one, and the open-endedness of “we will see how it goes” is uncomfortable when you are trying to decide whether you can afford it, plan it around the rest of your life, or commit to it at all.

The honest answer is that the number depends on the difficulty, but the range is narrower than people often expect. CBT is not designed to be open-ended. It is one of the few therapies for which the typical duration is known, well-studied, and built into the protocols themselves. Most pieces of CBT work fall inside a fairly predictable range. Below is what that range actually looks like in practice.

The short version

For most of the work I do, between eight and twenty sessions, at one session per week. The midpoint is around twelve. A small number of pieces of work end inside six sessions because the difficulty was narrow and specific; a small number run beyond twenty when the picture is more complex or has been present for a long time. Almost no piece of CBT work runs indefinitely.

The number is agreed near the start, not at the end. By the end of the first or second session, when we have understood the specific pattern of the difficulty and what the work will involve, I can usually give you a realistic estimate. We then check in on it regularly.

Typical ranges by condition

These are not rigid — every person is different — but they reflect what the evidence base and the clinical experience converge on. Treat them as orientation, not prescription.

  • Specific phobia. Often five to eight sessions. A specific phobia is one of the narrowest, best-understood pieces of CBT work, and it often resolves quickly once exposure is set up well. More on phobias.
  • Panic disorder. Around eight to fourteen sessions. Panic responds well to the standard CBT protocol — once the cycle of catastrophic interpretation, body sensation, and avoidance is mapped and worked on, the frequency tends to drop quickly. More on panic.
  • Generalised anxiety / chronic worry. Typically twelve to twenty sessions. Worry is more diffuse and woven into more of life than panic, so the work takes longer.
  • Social anxiety. Around twelve to twenty sessions. The work involves real-world exposure that has to be paced carefully, and the underlying beliefs about being judged are usually long-standing. More on social anxiety.
  • Health anxiety. Twelve to eighteen sessions. The reassurance-seeking cycle is well-mapped in CBT and tends to respond to a structured approach, but takes time because it is usually woven into daily routine. More on health anxiety.
  • OCD and intrusive thoughts. Often twelve to twenty, sometimes more. Exposure and response prevention is gradual and incremental by design; rushing it does not work. More on OCD.
  • Low mood / mild to moderate depression. Twelve to twenty sessions, often closer to sixteen. Mood work usually involves both behavioural activation in the early stages and cognitive work later. More on low mood.
  • Perfectionism and the high-functioning patterns. Twelve to twenty sessions. The beliefs underneath are long-standing and have usually been functional for years; loosening them takes time. More on perfectionism.
  • Insomnia (CBT-I). Often six to ten sessions. Sleep work has a well-defined protocol and a relatively quick response curve. More on sleep.
  • Burnout. Variable — ten to twenty sessions, depending on whether there are layers underneath (often there are). More on burnout.

What lengthens the number

A few things move a piece of work toward the longer end of its range:

  • The difficulty has been present for a long time. A pattern that has been operating for fifteen years has more layers than one that started six months ago. Neither is harder to work with in principle, but the longer version usually takes more sessions to fully shift.
  • More than one thing is going on. Anxiety and low mood often arrive together; OCD and health anxiety often overlap; perfectionism is rarely the only thing. We work on the most pressing piece first and the others follow, but the work takes longer when there are several pieces.
  • The pattern is woven into a relationship or role. When the difficulty is partly maintained by family, work, or relationship dynamics, the work takes longer because the environment is part of what needs to shift.
  • Homework is not happening between sessions. This is the biggest single factor. CBT works because the work continues between sessions; if it does not, sessions slow down. This is almost always worth talking about openly — sometimes the homework needs adjusting, sometimes life has got in the way, sometimes the homework was poorly chosen and needs replacing.

What shortens the number

  • The difficulty is narrow and specific. A clearly defined phobia, a single recurring pattern, a discrete piece of low mood tied to a specific event.
  • The person is already familiar with the language of CBT. If you have done a course of CBT before, the next round usually starts faster because the framework is already there.
  • Strong, consistent homework engagement. The biggest accelerator of all.
  • The difficulty is recent. Patterns that have been in place for under a year tend to shift faster than ones present for many years.

What “ending” actually means in CBT

A point that surprises some people: CBT does not aim to end with the difficulty completely gone. It aims to end with you knowing the difficulty well enough to manage it yourself if it shows up again. That distinction matters because it changes when ending is appropriate.

You are usually ready to end when:

  • The difficulty has reduced enough that it is no longer the central thing affecting your life.
  • You can describe, in your own words, the specific pattern that was keeping it going.
  • You have a clear sense of what to do if it shows up again.
  • You have been applying the techniques between sessions and finding them useful.

You are not waiting for a perfect baseline. CBT is built around the idea that the techniques become yours — not because you will need them constantly, but because you will know what to do if you do need them.

What if I need more sessions than expected?

This happens, and it is fine. The estimate at the start is exactly that — an estimate, based on what we know in session one or two. As we go, the picture becomes clearer, and sometimes the work turns out to be more involved than it first looked. We adjust openly. Therapy that quietly runs over the original estimate without anyone naming it is bad practice. Therapy that revisits the plan honestly when the picture changes is good practice.

The opposite also happens: people sometimes need fewer sessions than expected. The pattern is identified faster, the work lands quickly, and we wrap up earlier than planned. That is a good outcome, not a wasted plan.

How to think about it before you start

Two practical anchors:

  1. Plan for twelve. If you are deciding whether you can commit to therapy, planning for twelve sessions is a reasonable anchor for most pieces of work. If it takes fewer, that is a bonus. If it takes more, you will know by session four or five and can decide whether to continue.
  2. Block bookings. Many practices, including this one, offer a block of five sessions at a discount. That gives you a defined commitment, a meaningful chunk of work, and a natural review point at the end. My fees and block options are here.

If you are unsure whether CBT is the right approach at all, a free 15-minute consultation is the lowest-pressure way to find out. By the end of the call, you will usually have a much clearer answer about both the likely number of sessions and whether the fit is right.