Dexamethasone to Prednisone Conversion Calculator

Use the Dexamethasone to Prednisone Conversion Calculator

Free dexamethasone to prednisone conversion calculator. Convert any corticosteroid dose instantly using standard steroid equivalency ratios and charts.

How to Use Dexamethasone to Prednisone Conversion Calculator

1. Step 1: Choose the conversion direction

   Select your source steroid (the drug you are converting from) and target steroid (the drug you are converting to) using the dropdown menus or the quick-toggle buttons for Dex to Pred or Pred to Dex.

2. Step 2: Enter the dose

   Type the dose per administration in milligrams into the Dose field. You can also click a common dose preset button to fill it automatically.

3. Step 3: Set the dosing frequency

   Select how many times per day the medication is taken (QD, BID, TID, or QID) from the Times per day dropdown.

4. Step 4: Read the equivalent dose

   The calculator instantly shows the equivalent target steroid dose in mg/day, prednisone-equivalent dose, potency ratio, tablet suggestion, and a full equivalence table for all corticosteroids.

5. Step 5: Copy or reset

   Click Copy Summary to save the conversion result to your clipboard for documentation, or click Reset to start a new calculation.

Key Features

• Bidirectional dexamethasone-prednisone conversion with instant results
• Full 8-steroid equivalence table with half-life and mineralocorticoid data
• Tablet strength matching for real-world prescribing
• Common dose presets (COVID-19, asthma, antiemetic protocols)
• Dosing frequency adjustment (QD, BID, TID, QID)
• Copy-to-clipboard summary for clinical documentation

Understanding Results

Formula

The conversion uses standard corticosteroid equivalence ratios anchored to prednisone 5 mg:

Prednisone dose = Dexamethasone dose × (5 ÷ 0.75) = Dexamethasone dose × 6.667

Dexamethasone dose = Prednisone dose × (0.75 ÷ 5) = Prednisone dose × 0.15

For any two steroids, the general formula is: Target dose = Source dose × (Target equivalent dose ÷ Source equivalent dose). All equivalent doses reference prednisone 5 mg as the baseline.

Reference Ranges & Interpretation

Corticosteroid doses are classified by prednisone-equivalent intensity:

• Low dose: ≤7.5 mg prednisone/day — chronic maintenance, minimal side effects
• Moderate dose: 7.5–30 mg/day — active disease management, monitor glucose and blood pressure
• High dose: 30–100 mg/day — acute flares, significant side-effect risk
• Very high dose: >100 mg/day — pulse therapy, requires close monitoring

Assumptions & Limitations

This calculator assumes systemic oral or IV dosing. Key limitations include:

• Equivalence reflects anti-inflammatory potency only, not mineralocorticoid, bone, or metabolic effects
• Does not account for topical, inhaled, or intra-articular routes which have different potency rankings
• Prednisone is a prodrug requiring hepatic activation to prednisolone — in severe liver disease, prednisolone or dexamethasone may be preferred
• Individual patient response, formulation bioavailability, and indication-specific protocols may require dose adjustments beyond simple equivalence

Dexamethasone to Prednisone Conversion: What Clinicians Actually Need to Know

Dexamethasone to prednisone conversion is the single most common corticosteroid dose switch in clinical practice — and getting the ratio wrong can mean the difference between therapeutic relief and a flare. The standard equivalence factor is straightforward: 0.75 mg dexamethasone equals 5 mg prednisone in anti-inflammatory potency, giving dexamethasone roughly 6.7 times the glucocorticoid punch milligram-for-milligram. But the number alone doesn't tell the whole story.

This guide walks through the conversion math with real-world examples, explains why the two drugs aren't interchangeable in every scenario, and flags the clinical nuances — half-life, mineralocorticoid activity, formulation — that equivalence tables leave out.

The 0.75:5 Conversion Factor

Every corticosteroid equivalence table anchors to the same baseline: how many milligrams of a given steroid produce the same anti-inflammatory effect as 5 mg of prednisone? For dexamethasone the answer is 0.75 mg. That yields a potency multiplier of 6.67x (5 ÷ 0.75).

The conversion formula is simple algebra:

Going the other direction is just the reciprocal:

These factors come from published potency ratios standardized in pharmacology references since the 1960s and remain the accepted values in current guidelines from the American College of Rheumatology and major formularies.

Worked Examples: Dex 4 mg, 6 mg, 8 mg

Three doses cover the vast majority of clinical scenarios. Here's the math, step by step.

The RECOVERY trial famously used dexamethasone 6 mg daily for COVID-19. That's 40 mg prednisone-equivalent — a high dose by rheumatology standards but standard for acute respiratory failure. When providers needed to switch patients from IV dexamethasone to oral prednisone at discharge, this conversion became one of the most-Googled clinical questions of 2020-2021.

Dexamethasone vs. Prednisone: Beyond Potency

Potency equivalence tables are useful shortcuts, but they flatten three important differences between these two drugs.

That mineralocorticoid gap is significant. Prednisone causes more sodium retention and potassium wasting than dexamethasone at equivalent anti-inflammatory doses. For patients with heart failure or uncontrolled hypertension, dexamethasone's negligible mineralocorticoid effect can be an advantage — but its long half-life introduces different risks.

Why Half-Life Matters More Than You Think

Dexamethasone's biological half-life of 36-54 hours means a single morning dose suppresses the HPA axis for nearly two full days. Prednisone, at 12-36 hours, clears faster and allows some adrenal recovery between doses. This is why most rheumatologists prefer prednisone for chronic use: it's easier to taper, and alternate-day dosing can partially spare adrenal function.

In acute settings — chemotherapy-induced nausea, cerebral edema, anaphylaxis rescue — the long half-life is actually desirable. One dose of dexamethasone covers a longer period without redosing. But if you're converting a patient from acute IV dexamethasone to chronic oral maintenance, switching to prednisone (or prednisolone) gives you much finer taper control. Our steroid conversion calculator handles multi-drug equivalencies for exactly these scenarios.

Four Mistakes That Change the Outcome

1. Forgetting the frequency. A patient on dexamethasone 4 mg twice daily is taking 8 mg/day, not 4 mg/day. That's 53.3 mg prednisone-equivalent, not 26.7 mg. Always convert the total daily dose.

2. Treating conversion as one-to-one for all effects. Anti-inflammatory potency ratios don't predict mineralocorticoid effects, bone loss rates, or glucose impact proportionally. Dexamethasone 4 mg and prednisone 26.7 mg suppress inflammation equally, but they don't cause equal sodium retention.

3. Using the conversion for topical or inhaled routes. The 0.75:5 ratio applies to systemic oral and IV dosing. Topical potency rankings are different — betamethasone cream, for instance, isn't “8.3 times stronger” than prednisolone cream in the way the systemic table implies.

4. Converting without adjusting the schedule. Switching from once-daily dexamethasone to once-daily prednisone may leave therapeutic gaps at the end of the dosing interval because prednisone clears faster. For some indications, splitting the prednisone dose into BID (twice daily) better covers the 24-hour period. A dosage calculator can help verify the per-dose math after splitting.

When to Convert (and When Not To)

The conversion is appropriate when:

• Switching formulations due to drug availability, cost, or formulary requirements
• Transitioning from IV to oral after acute illness (e.g., post-COVID discharge)
• Initiating a taper — converting to intermediate-acting prednisone for finer dose steps
• Comparing regimen intensity across studies or guidelines that use different steroids

It's not appropriate when:

• The indication specifically requires dexamethasone (e.g., fetal lung maturation uses dexamethasone, not prednisone)
• You need to convert for topical, inhaled, or intra-articular routes
• The patient has severe hepatic impairment — prednisone is a prodrug that requires hepatic conversion to prednisolone, while dexamethasone is active as-is

That last point catches people off guard. In advanced liver disease, prednisolone or dexamethasone may be preferred over prednisone because they don't require hepatic activation. Our mg/mL dose calculator can help with liquid formulations when tablet forms aren't feasible.

Other Steroid Equivalencies at a Glance

Dexamethasone and prednisone are the most commonly converted pair, but the full equivalence landscape includes eight systemic corticosteroids. Here's how they stack up relative to 5 mg prednisone:

Betamethasone is actually slightly more potent than dexamethasone (8.33x vs. 6.67x), but it's used less often for systemic therapy in most countries. For a full multi-steroid converter, see our steroid conversion calculator.

References

1. Liu D, Ahmet A, Ward L, et al. “A practical guide to the monitoring and management of the complications of systemic corticosteroid therapy.” Allergy Asthma Clin Immunol. 2013;9(1):30. doi:10.1186/1710-1492-9-30
2. RECOVERY Collaborative Group. “Dexamethasone in Hospitalized Patients with Covid-19.” N Engl J Med. 2021;384:693-704. doi:10.1056/NEJMoa2021436
3. Schimmer BP, Funder JW. “ACTH, Adrenal Steroids, and Pharmacology of the Adrenal Cortex.” In: Brunton LL, ed. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 13th ed. McGraw-Hill; 2018.

Frequently Asked Questions