What is a diazepam equivalent dose?

A diazepam equivalent dose is the amount of a given benzodiazepine that produces roughly the same clinical effect as 10 mg of diazepam (Valium). Because all benzodiazepines bind to the same GABA-A receptor but differ in potency, half-life, and speed of onset, these equivalency ratios allow clinicians to compare doses across drugs. For example, 1 mg of lorazepam is approximately equivalent to 10 mg of diazepam, and 0.5 mg of alprazolam is approximately equivalent to 10 mg of diazepam. These ratios are derived from published pharmacological literature and clinical guidelines.

Are benzodiazepine equivalency ratios exact?

No. Published equivalency ratios are approximate averages derived from clinical studies and expert consensus. Individual responses vary due to differences in metabolism, tolerance, age, renal and hepatic function, and the specific indication being treated. Different reference sources also publish slightly different values. Equivalency tables are a starting point for clinical decision-making, not a substitute for individual patient assessment. Any dose change should be managed by a qualified prescriber.

Which benzodiazepines are available in New Zealand?

Benzodiazepines that are funded or available on prescription in New Zealand include diazepam, lorazepam, clonazepam, temazepam, oxazepam, nitrazepam, midazolam, and triazolam. Alprazolam is available but not fully funded under PHARMAC. Chlordiazepoxide and clobazam are also available for specific indications. All benzodiazepines are Class C controlled substances under the Misuse of Drugs Act 1975 and require a prescription. Supply without a prescription is a criminal offence.

Benzodiazepine Conversion Calculator

Convert a dose from one benzodiazepine to its approximate equivalent dose in another using published diazepam equivalency ratios. Enter the drug and dose you are converting from, then select the drug you want to convert to.

This tool is for educational and reference purposes only. Dose adjustments must be managed by a qualified prescriber.

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Important: This calculator uses published pharmacological equivalency ratios for educational reference. These ratios are approximate and individual responses vary. Never adjust, stop, or switch benzodiazepine doses without guidance from a doctor or pharmacist. Abrupt benzodiazepine withdrawal can cause serious harm including seizures.

Reference 2025 Equivalency ratios based on Ashton Manual (2002), Benzodiazepine equivalency table (Lader 1994), and NZ BPAC prescribing guidance.

1. From Drug and Dose

Convert from drug

Dose (mg)

2. To Drug

Convert to drug

Rounding

Conversion Result

Diazepam Equivalent

mg diazepam

Equivalent Dose
-
mg

Potency Ratio

times more potent than diazepam

Conversion Breakdown

From drug-

From dose-

Equivalency ratio (from)-

Diazepam equivalent-

Equivalency ratio (to)-

Equivalent dose (to)-

Drug Properties

From drug half-life-

To drug half-life-

From drug: diazepam equiv per mg-

To drug: mg per 10mg diazepam-

Onset type (from drug)-

Duration (from drug)-

Full Equivalency Reference Table

Drug (brand name)	mg equiv to 10mg diazepam	Diazepam equiv per mg	Half-life (hours)	Duration

How Benzodiazepine Conversion Works

All benzodiazepines work by enhancing the effect of gamma-aminobutyric acid (GABA) at the GABA-A receptor in the brain. Despite sharing the same mechanism, they differ greatly in potency, how quickly they take effect, and how long they last. Diazepam has been used as the reference standard for dose equivalency because it was one of the earliest and most studied members of the class.

The conversion formula uses a two-step process. First, the from-drug dose is converted to its diazepam equivalent:

Diazepam equivalent (mg) = Dose (mg) / Equivalency dose x 10

where the equivalency dose is the number of milligrams of the from-drug equal to 10 mg of diazepam. Then the diazepam equivalent is converted to the to-drug:

To-drug dose (mg) = Diazepam equivalent (mg) / 10 x Equivalency dose of to-drug

Equivalency Ratios Used

The table below shows the published equivalency values used by this calculator. These are derived from the Ashton Manual (Professor Heather Ashton, 2002), which is a widely referenced source for clinical benzodiazepine equivalency, supplemented by Lader (1994) and New Zealand BPAC prescribing guidance.

Drug	mg equal to 10mg diazepam	Typical half-life	Notes
Diazepam (Valium)	10 mg	20-100 hours	Reference drug; long acting with active metabolites
Alprazolam (Xanax)	0.5 mg	6-12 hours	High potency; short to intermediate acting
Clonazepam (Rivotril)	0.5 mg	18-50 hours	High potency; long acting; used in epilepsy
Lorazepam (Ativan)	1 mg	10-20 hours	Intermediate potency; no active metabolites
Oxazepam (Seresta)	20 mg	4-15 hours	Low potency; short acting; safe in liver disease
Temazepam (Normison)	20 mg	8-22 hours	Low to medium potency; short acting; sleep use
Nitrazepam (Mogadon)	10 mg	16-48 hours	Medium potency; intermediate to long acting
Triazolam (Halcion)	0.25 mg	2-5 hours	Very high potency; ultra-short acting
Midazolam (Versed)	7.5 mg	1-4 hours	Short acting; used in procedural sedation
Chlordiazepoxide (Librium)	25 mg	5-30 hours	Low potency; used in alcohol withdrawal
Clobazam (Frisium)	20 mg	12-60 hours	Low potency; used in epilepsy

Worked Example

Converting 1 mg alprazolam to its diazepam equivalent:

Alprazolam equivalency dose: 0.5 mg alprazolam = 10 mg diazepam
Diazepam equivalent = (1 / 0.5) x 10 = 20 mg diazepam

This matches the calculator's default output: 1 mg alprazolam converts to 20 mg diazepam.

Clinical Considerations

Switching between benzodiazepines is not a simple dose substitution. Key factors that affect how a switch plays out in practice include:

Tolerance: Long-term users may have developed tolerance, meaning published equivalencies may underestimate what is needed during a switch.
Half-life: Switching from a short-acting drug (such as alprazolam) to a long-acting drug (such as diazepam) changes the onset and duration of effect significantly. Diazepam's long half-life and active metabolites allow slow, stable tapering.
Cross-tolerance: All benzodiazepines share cross-tolerance, which is the basis for switching. However, partial cross-tolerance means the equivalent dose should initially be conservative.
Indication: The dose required for sleep, anxiety, muscle relaxation, or seizure control may differ even within the same drug.
Patient population: Older adults, people with hepatic or renal impairment, and pregnant women require modified dosing that these general equivalencies do not capture.

These equivalencies are intended as a reference for healthcare professionals and informed patients, not as a prescription or treatment recommendation.

Benzodiazepines in New Zealand

In New Zealand, benzodiazepines are classified as Class C controlled substances under the Misuse of Drugs Act 1975. They are only legally available on prescription. PHARMAC funds several benzodiazepines on the Pharmaceutical Schedule, including diazepam, lorazepam, clonazepam, temazepam, oxazepam, nitrazepam, and midazolam. Alprazolam requires a special authority and has limited subsidy. All prescribers dispensing benzodiazepines in New Zealand must comply with Medicines Regulations 1984 requirements for controlled drug prescriptions.

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Sources and method: Equivalency ratios from: Ashton H. Benzodiazepines: How They Work and How to Withdraw (The Ashton Manual), 2002 (revised 2011); Lader M. Treatment of anxiety. BMJ 1994; BPAC NZ. Benzodiazepines and zopiclone, 2022 (bpac.org.nz). Half-lives from NZ Medicines Datasheet (Medsafe.govt.nz). This calculator is for educational and reference use only and does not constitute medical advice.