How this instrument works
Benzodiazepine equivalency tables express every drug's strength against one shared reference: diazepam 10 mg. Each drug on this list carries a factor showing how many of its milligrams match that reference dose — diazepam 10, lorazepam 1, alprazolam 0.5, clonazepam 0.5, temazepam 20, oxazepam 20, chlordiazepoxide 25. Divide one factor by another and a dose of any listed drug converts to its match in any other, the same arithmetic clinicians use when planning a switch between agents.
The table traces to Professor C. H. Ashton's 2002 manual, 'Benzodiazepines: How They Work and How to Withdraw,' still hosted by the Benzodiazepine Information Coalition and cited constantly in withdrawal and tapering literature. It is worth being honest about how firm these numbers are: sources genuinely disagree at the margins — some list alprazolam anywhere from 0.25 to 0.5 mg, or chlordiazepoxide from 25 to 30 mg — so treat the figures here as the standard, most commonly cited values rather than one universally fixed conversion.
The clearest real-world use of this arithmetic sits in tapering. Someone dependent on a short, fast-acting drug like alprazolam often struggles with sharp between-dose withdrawal symptoms, so clinicians frequently convert the patient's total daily dose to an equivalent amount of diazepam first. Diazepam's long half-life, stretched further by active metabolites, smooths out the peaks and troughs that make a short-acting drug so hard to step down from, turning a rough taper into a gradual, more tolerable one.
- Enter the known dose in milligrams.
- Choose the drug you are converting from in the first menu.
- Choose the drug you are converting to in the second menu.
- Read the matching dose; the working block shows the ratio applied to the original figure.
Worked example — 10 mg diazepam to lorazepam
A patient takes 10 mg of diazepam daily and the plan is to switch to lorazepam. Diazepam's factor is 10, lorazepam's is 1: 10 × (1 ÷ 10) = 1 mg. Ten milligrams of the reference drug collapses to a single milligram of the far more potent one.
The same ratio runs both directions and across the full list. Half a milligram of alprazolam, factor 0.5, converts to 0.5 × (20 ÷ 0.5) = 20 mg of temazepam — a fortyfold jump in the raw number despite an identical clinical effect. And 25 mg of chlordiazepoxide, factor 25, works out to 25 × (0.5 ÷ 25) = 0.5 mg of clonazepam, showing how differently the same relative strength reads across seven drugs.
Questions
Are these conversion ratios one exact, universally agreed standard?
No — treat them as the most commonly cited values, not a fixed law. Different formularies and references list slightly different numbers at the margins; alprazolam appears variously as 0.25 to 0.5 mg and chlordiazepoxide as 25 to 30 mg depending on the source. The Ashton Manual's figures used here are widely reproduced and taught, but real prescribing always leans on clinical judgment alongside the table.
Why would a clinician convert a patient to diazepam before tapering?
Because diazepam's long half-life and active metabolites keep blood levels steadier between doses than a short-acting drug like alprazolam or lorazepam can manage. Converting to an equivalent diazepam dose first, then reducing that dose gradually, produces a smoother taper with fewer sharp between-dose withdrawal symptoms than stepping down the original short-acting drug directly.
Why is diazepam 10 mg the reference point rather than a smaller number?
Because diazepam was among the earliest and most studied benzodiazepines, and 10 mg became the conventional dose against which every other drug's strength was benchmarked. Every factor in the table describes how many milligrams of that drug produce a comparable effect to that reference dose.
Can I use this figure to switch a patient's benzodiazepine directly?
Treat the output as a starting reference, not a finished prescription. A real switch also depends on how long someone has taken the original drug, current dose, tolerance, other medications, and individual sensitivity — a qualified clinician should oversee any change rather than a milligram figure alone deciding it.
Why does alprazolam convert to such a large number of temazepam milligrams?
Because alprazolam is far more potent per milligram than temazepam — roughly forty times, based on these factors — so matching its effect takes a much larger raw dose of the weaker drug. The gap in milligrams reflects potency, not any difference in how strong the drugs actually feel at their matched doses.
Do all seven of these drugs share the same speed of onset and duration?
No. Alprazolam and lorazepam act relatively fast and clear the body within roughly six to twenty hours, while diazepam and its active metabolites can linger for days. Two doses that match perfectly on this potency scale can still feel very different in how quickly they take effect and how long that effect lasts.
References
- Ashton CH, 'Benzodiazepines: How They Work and How to Withdraw' (2002) — Benzodiazepine Information Coalition
- ASAM/AAAP Joint Clinical Practice Guideline on Benzodiazepine Tapering (2025)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.