Steroid Calculator

Corticosteroids all bind the same glucocorticoid receptor inside cells, but they bind with different affinity and for different lengths of time. That difference is why 1 mg of dexamethasone hits harder than 1 mg of prednisone — the molecule fits the receptor better and holds on longer. The equivalency table captures that difference as a single number: anti-inflammatory potency relative to hydrocortisone, which is set at 1.0 as the baseline. Prednisone is 4 times as potent as hydrocortisone, methylprednisolone is 5 times, and dexamethasone reaches 25 times.

To convert between any two steroids, the tool first converts your source dose into a hydrocortisone equivalent. This puts both drugs on the same scale. It then divides by the target drug's potency to get the dose that delivers the same anti-inflammatory effect. The math is simple: (source dose x source potency) divided by target potency. What makes the calculation useful is having accurate potency ratios — the numbers in this tool reflect values used consistently across clinical pharmacology references.

One thing the single equivalency number does not capture is duration of action. Hydrocortisone is active for 8-12 hours. Dexamethasone lasts 36-54 hours. A once-daily dexamethasone dose actually provides more cumulative suppression than the mg equivalency alone suggests. This is why the tool flags dexamethasone conversions specifically — the number is right for a single dose, but the clinical picture is more complicated when switching schedules.

Use this tool when switching between oral corticosteroids due to formulary restrictions, patient preference, or drug availability. It is also useful for verifying that a prescribed dose is in the expected range relative to what was given before. Pharmacists, prescribers, and clinical students use equivalency tables constantly when rounding or transitioning patients.

Use it with caution when converting from short-acting to long-acting agents like dexamethasone. The equivalency number is correct for instantaneous potency, but the longer half-life means the drug accumulates and the effective dose over 24 hours is higher than a single conversion suggests. The same applies in reverse: when converting from dexamethasone to a shorter-acting agent, the patient may experience a functional gap in coverage before the new drug fully takes effect.

Do not use this tool as the sole basis for designing an adrenal suppression taper, adjusting doses for renal or hepatic impairment, or converting to inhaled or topical steroids. Inhaled corticosteroids have different potency tables and systemic bioavailability assumptions that make oral-to-inhaled conversions unreliable with this approach. For those scenarios, the output here should be treated as a rough starting point, not a final answer.

The most common mistake is treating all mg the same without checking which drug is involved. Someone seeing a prescription for 4 mg dexamethasone might assume it is underdosed compared to 40 mg prednisone — when in fact 4 mg dexamethasone is 25 mg prednisone-equivalent. The consequences of this error in either direction include under-treating inflammation or giving a dose that suppresses the adrenal axis more aggressively than intended.

A second common error is forgetting that mineralocorticoid activity does not follow the same ratio as anti-inflammatory potency. When a patient on hydrocortisone — which has significant mineralocorticoid effect — is switched to dexamethasone or betamethasone, the equivalent dose calculation handles the inflammatory component correctly but leaves a gap in salt and water retention. Patients with adrenal insufficiency can become hemodynamically unstable if this gap is missed.

A third mistake specific to this tool is entering a total daily dose when the per-dose amount is what is needed for the calculation, or vice versa. If someone takes 10 mg prednisone four times a day and enters 40 mg as the dose, the equivalent will be four times too large. Always confirm whether the dose entered is per-administration or per-day before acting on the output.

The core formula is: Target Dose = (Source Dose x Source Potency) / Target Potency.

Potency values are expressed relative to hydrocortisone = 1.0. The table used here: Hydrocortisone 1.0, Cortisone 0.8, Prednisone 4.0, Prednisolone 4.0, Methylprednisolone 5.0, Triamcinolone 5.0, Dexamethasone 25.0, Betamethasone 25.0. These are anti-inflammatory glucocorticoid potency ratios only.

For a 40 mg prednisone dose converting to methylprednisolone: (40 x 4) / 5 = 32 mg methylprednisolone. For converting 100 mg hydrocortisone to dexamethasone: (100 x 1) / 25 = 4 mg dexamethasone. The hydrocortisone equivalent per dose is just source dose x source potency, which gives you the common currency for comparing any two steroids at a glance.

Clinicians sometimes overlook that prednisone and prednisolone are listed as equivalent in the table, but they are not identical in patients with liver disease. Prednisone is a prodrug converted to prednisolone hepatically — in cirrhotic patients, this conversion is impaired and prednisolone is preferred. The equivalency ratio of 1:1 is accurate for healthy liver function only. Similarly, the 25x potency of dexamethasone versus hydrocortisone is for systemic glucocorticoid effect: dexamethasone penetrates the blood-brain barrier more effectively than prednisone, which is part of why it is the preferred agent for cerebral edema and is not interchangeable by potency ratio alone in that context.