Key Takeaways
- Table 1 of the Ashton Manual lists clonazepam (Klonopin) 0.5 mg as approximately equivalent to diazepam (Valium) 10 mg, and that one row is the whole of the 1:20 ratio.
- The equivalents rest on clinical experience and vary between people, so the ratio is a starting estimate, not a fact about any one person.
- The Manual moves a Klonopin taper onto diazepam because diazepam comes in far smaller steps. The smallest Klonopin tablet already equals 10 mg of diazepam, while a 1 mg piece of diazepam equals about 0.05 mg of clonazepam.
- Substitution goes one dose at a time, usually the evening dose first, and the daily diazepam equivalent stays level through the substitution stages, which take roughly six weeks in the Manual’s clonazepam schedule.
- Once the clonazepam is gone, the diazepam comes down in steps that get smaller toward the end, each held for one to two weeks or longer.
- The Manual prefers standing still at a dose to going backwards, while the Klonopin label allows a return to the previous dose, and which fits a given week is decided with the prescriber.
- Symptoms after any change arrive on a delay of several days, so each stage is judged across its full week. A seizure or thoughts of self-harm are emergencies.
- A Klonopin taper without diazepam is possible, which the Manual allows for people who have particular difficulty switching, and either route is taken slowly.
What does Ashton’s 1:20 conversion actually say?
It says less than the internet claims for it. Table 1 of the Ashton Manual, “Benzodiazepines: How They Work and How to Withdraw” by the late Professor C. Heather Ashton, lists clonazepam (Klonopin) at an approximately equivalent oral dose of 0.5 mg against diazepam (Valium) at 10 mg. That is the whole of the 1:20 ratio: one row of a table, and the arithmetic that follows from it.
If 0.5 mg of clonazepam stands in for 10 mg of diazepam, then 1 mg stands in for 20 mg, and a person taking 0.5 mg three times a day is taking the equivalent of about 30 mg of diazepam. The table’s footnote says the equivalents are based on clinical experience and may vary between individuals: a starting estimate, not a fact about any one person’s brain.
The ratio is not a method. The method is in Chapter II and in the Manual’s clonazepam schedule, Schedule 5 in the online edition.
A person who has taken Klonopin as prescribed and now needs a careful taper has physical dependence, which the Klonopin label, carrying the 2020 United States Food and Drug Administration (FDA) boxed warning update, describes as a state that develops from continued use and shows itself as withdrawal when the dose falls. Dependence is not addiction. It is a predictable adaptation, and the treatment that matches it is a slow, patient-paced reduction.
Why the Manual moves a Klonopin taper onto diazepam.
Klonopin is potent, and potency is the problem. The smallest Klonopin tablet is 0.5 mg, and per the label only that strength is scored. Since the smallest tablet already equals 10 mg of diazepam, even a quarter of one is a 2.5 mg diazepam-sized step, while diazepam comes in 2 mg tablets that halve to 1 mg, the equivalent of only 0.05 mg of clonazepam.
Think of it as a staircase. A flight with ten-inch steps can be walked down, but every step is a jolt; rebuild the same descent with one-inch steps and no single step is big enough to fall from. The switch does not shorten the descent. It makes the steps small.
Half-life matters less here than for lorazepam or alprazolam, because clonazepam is already long-acting: Table 1 gives it 18 to 50 hours, and the Klonopin label says typically 30 to 40. Diazepam’s active metabolite persists up to 200 hours, and the Manual counts that difference among its reasons; in this site’s reading the decisive advantage is still the fineness of the steps.
The Manual is direct about clonazepam itself. In Chapter II, Professor Ashton writes that Klonopin is far from ideal as a substitute for withdrawal because it is an extremely potent drug, is eliminated much faster than diazepam, and comes in nothing smaller than a 0.5 mg tablet in the United States, and she notes some evidence that withdrawal is particularly difficult from high-potency benzodiazepines, Klonopin included.
The Manual replaces clonazepam one dose at a time, not all at once.
Here is where most rewrites go wrong. Chapter II says to substitute one dose at a time, usually starting with the evening or night-time dose, and Schedule 5 shows what that looks like for a person taking 0.5 mg of clonazepam morning, midday and night. In stage one only the evening dose changes: half of it, 0.25 mg, becomes 5 mg of diazepam. In stage two the evening dose becomes 10 mg of diazepam and the evening clonazepam stops.
The morning and midday doses are then halved and stopped in turn, the two exchanges overlapping across stages three to six at one stage a week, and at the sixth stage the last 0.25 mg of clonazepam is gone. The Manual marks the first five stages as diazepam substitution with no actual withdrawal: the daily total stays at about 30 mg of diazepam equivalent through those five stages.
So the crossover takes roughly six weeks, not one or two, and there is no separate stabilization period at the end; the reductions begin as the substitution completes. Earlier versions of this article described a one-to-two-week crossover and stabilization stage and called it the Ashton Method; Ashton Manual Guide has corrected that.
Then the diazepam comes down slowly, and slower at the end.
Once the clonazepam is gone the schedule turns to reducing diazepam, and Chapter II gives the shape rather than a rule: 2 mg steps every one to two weeks from higher doses, 1 mg steps lower down, and 0.5 mg steps at the lowest doses. Professor Ashton’s general guidance is to reduce by up to one tenth at each decrement, and she writes that many people have taken a year or more.
Schedule 5 follows that shape from 30 mg: 2 mg steps at one-to-two-week intervals until the daily total is around 10 mg, then 1 mg every two weeks. These are the Manual’s illustrations for one starting dose, not instructions for a reader. A person’s own numbers come from their prescriber, and the Klonopin taper calculator on this site shows how a schedule of this shape is laid out from any starting dose, as a planning tool and nothing more.
Notice what the shape does at the bottom. A 2 mg cut from 30 mg is about seven percent; from 10 mg it is twenty, and the Manual halves the step on the way down. The hyperbolic taper of the Maudsley Deprescribing Guidelines shrinks every step in proportion to what remains, a refinement of that principle rather than a departure from it.
The Manual says never go backwards, but standing still is allowed.
The Manual’s rule on setbacks is stricter than most summaries of it. Professor Ashton writes that a person should, as far as possible, never go backwards, and that they can instead stand still at a certain stage in the schedule and have a vacation from further withdrawal for a few weeks. A hold is not a failure of the taper. It is one of its tools.
The Manual is equally clear about who sets the pace: the person tapering must be in control and must proceed at the pace that is comfortable for them. A taper that takes a year and a half without a bad month is a better taper than one that takes eight months and ends in a crisis.
The Klonopin label takes a different line: if withdrawal reactions develop, the prescriber may consider pausing the taper or returning to the previous dose level, then reducing more slowly. The Manual would rather hold than step back up, and which fits a given week is a conversation for the person and their prescriber.
What the crossover feels like, and when to judge it.
Often, not much. Because both drugs are long-acting, the substitution stages tend to pass with less drama than the later reductions; many people notice mainly that diazepam feels a little more sedating, or a little less calming. Symptoms after any change arrive on a delay of several days, so the day after a stage change is the worst moment to judge it.
Judge each stage across its full week, and treat what shows up as information about pace rather than evidence of harm. A day-by-day symptom diary beats any published timeline; the longer arc is in this site’s article on clonazepam withdrawal symptoms and their timeline.
Two things sit outside pacing. Klonopin is also prescribed for seizure disorders, and its label warns that abrupt discontinuation or rapid reduction can precipitate withdrawal reactions including seizures, which can be life-threatening. A seizure, severe confusion, hallucinations, or thoughts of self-harm are emergencies: call 911 or local emergency services, and in the United States the 988 Suicide and Crisis Lifeline answers calls and texts at any hour.
The pattern repeats often enough to describe.
A composite will serve better than a case. A person has taken clonazepam 0.5 mg three times a day for years, first for panic and now mostly to keep the mornings level. An attempt to drop the midday tablet outright brought two weeks of shaking and sleeplessness, and the tablet went back in.
On the Manual’s plan the person changes nothing for a week except half the bedtime dose. Six weeks later there is no clonazepam left and the diazepam total has barely moved; the reductions then run in 2 mg steps, later 1 mg, with one month-long hold along the way, and the last milligrams take longer than the first twenty. The shape is what matters, not the calendar.
Can a Klonopin taper be done without diazepam at all?
Yes, and the Manual itself allows for it. Chapter II says that some people have particular difficulty switching from Klonopin to diazepam, and that in such cases special capsules can be made up holding an eighth or a sixteenth of a milligram or less, so that gradual reductions can be made straight from Klonopin. The Klonopin label’s own discontinuation guidance also assumes a direct taper.
This site would add a second case in its own voice. Where a compounded liquid or small capsules solve the tablet problem and the dose is already low, the Manual’s remaining objection is a half-life that is still long by benzodiazepine standards.
The Maudsley Deprescribing Guidelines treat the diazepam switch as an option rather than a routine step, and favor proportional reductions of the original drug when its dose forms allow it. Ashton Manual Guide reads this as consistent with the Manual: the goal was always small steps, and diazepam was the tool that made them possible when the Manual was written. Above a few milligrams a day the switch still offers the smaller step; either route works, and neither is fast.
Questions readers ask about the Klonopin crossover.
Does 1 mg of Klonopin equal 20 mg of diazepam for everyone?
No. Table 1’s equivalents vary between individuals, and the one-dose-at-a-time stages exist partly to find out whether the estimate fits.
Why not switch the whole dose to diazepam in one day?
Because diazepam takes days to reach steady levels, and the person would not know which change caused what. The Manual exchanges one dose at a time, evening first, at intervals of a few days to a week, so each stage can be judged on its own.
Why might diazepam feel different from Klonopin during the switch?
Because the equivalents are estimates, and diazepam builds up slowly over repeated doses. The Manual’s aim is a dose of diazepam that largely prevents withdrawal symptoms but is not so excessive as to make the person sleepy, and the one-dose-at-a-time exchange exists partly to find that dose for that person.
The Maudsley Deprescribing Guidelines, which handle the switch a little differently from the Manual’s schedule, note that a period of stabilization on the new drug, of two weeks or longer, may be required before a taper starts. They also say that the person’s own reported symptoms should guide any adjustment. So, a little more sedation or a little less calm in the first weeks is information for the prescriber, not a verdict on the switch.
How long does a Klonopin taper take with the Ashton method?
There is no fixed length. In the Manual’s clonazepam schedule the crossover alone takes roughly six weeks, and the diazepam reductions that follow are held one to two weeks each and get smaller toward the end, which is why Professor Ashton wrote that many people have taken a year or more.
Her own view of the calendar was relaxed: “Whether it takes 6 months, 12 months or 18 months is of little significance if you have taken benzodiazepines for a matter of years.” The pace belongs to the person tapering, and a hold along the way is part of the method rather than a delay in it.
The Manual is free to read at benzo.org.uk, and Schedule 5 is short enough to read in a few minutes alongside a prescriber. That is a better afternoon’s work than any summary of it, this one included.
This article is educational. It is not medical advice, and reading it does not create a doctor-patient relationship. Decisions about starting, continuing, or tapering any medication should be made with your own physician.
