Steroid conversion calculator (corticosteroid equivalency)
This tool converts a dose of one oral or IV corticosteroid into the roughly equivalent anti-inflammatory dose of another, using the standard glucocorticoid potency table (hydrocortisone 20 mg = prednisone 5 mg = methylprednisolone 4 mg = dexamethasone 0.75 mg, and so on). It answers one narrow question — "how much of drug B delivers about the same anti-inflammatory strength as this dose of drug A?" It does not tell you whether the switch is appropriate, how to taper, or how the two drugs differ in salt retention and duration.
How it works
Each steroid has a published equivalent dose — the milligram amount that produces about the same glucocorticoid (anti-inflammatory) effect as 20 mg of hydrocortisone. The standard values are: hydrocortisone 20, cortisone 25, prednisone 5, prednisolone 5, methylprednisolone 4, triamcinolone 4, dexamethasone 0.75, betamethasone 0.6 (mg). To convert, the tool divides out the source drug's potency and multiplies in the target's: target dose = source dose x (target equivalent / source equivalent). Because the numbers are inverse to potency, a smaller equivalent value means a more potent drug, so it takes fewer milligrams to match the same effect.
Worked example
Convert 40 mg of prednisone to methylprednisolone. Prednisone's equivalent dose is 5 mg and methylprednisolone's is 4 mg, so: 40 x (4 / 5) = 32 mg of methylprednisolone. Going the other direction, 40 mg of prednisone converts to dexamethasone as 40 x (0.75 / 5) = 6 mg — a much smaller number, because dexamethasone is far more potent per milligram and also much longer-acting.
Important
Estimate only, for general education — not medical advice, and not a substitute for your prescriber or pharmacist. Figures are approximate, apply to adults, and assume systemic (oral or IV) dosing; they do not apply to inhaled, topical, intra-articular, or ophthalmic steroids, or to children, pregnancy, and liver or kidney impairment without clinician adjustment. Three limits are built into this math and you must not ignore them: (1) These equivalents match GLUCOCORTICOID (anti-inflammatory) potency ONLY. They say nothing about mineralocorticoid (salt- and fluid-retaining) activity — hydrocortisone and cortisone have substantial mineralocorticoid effect, prednisone/prednisolone have a modest amount, and methylprednisolone, triamcinolone, dexamethasone, and betamethasone have essentially none, so an anti-inflammatory-equal switch can change blood pressure, sodium, and potassium. (2) They do NOT account for duration. Biological half-lives differ enormously — hydrocortisone/cortisone are short-acting (~8-12 h), prednisone/prednisolone/methylprednisolone/triamcinolone intermediate (~18-36 h), and dexamethasone/betamethasone long-acting (~36-54 h) — so equal daily milligrams can mean very different around-the-clock exposure and HPA-axis suppression. (3) This tool does NOT tell you how to taper or safely switch a chronic steroid. Stopping or changing a steroid taken for more than about two to three weeks can trigger adrenal insufficiency, an adrenal crisis, or a flare of the underlying disease. Do not start, stop, switch, or adjust a corticosteroid based on this number — confirm any change with your clinician.