Levodopa Equivalent Daily Dose (LEDD) Calculator
Enter each medication's total daily dose in mg/day. The tool estimates total LEDD using common conversion factors.
What is a levodopa calculator?
A levodopa calculator estimates Levodopa Equivalent Daily Dose (LEDD), which is a standardized way to compare Parkinson's disease medication regimens. Because different drugs have different potencies, LEDD helps clinicians and researchers translate multiple medicines into one common scale.
For example, two people may take very different medication combinations but still have similar total dopaminergic exposure. LEDD helps make that comparison clearer.
Why LEDD matters
- Medication review: Helps summarize total dopaminergic burden during clinic visits.
- Switching therapies: Supports rough planning when transitioning between agents.
- Research and audits: Provides a consistent framework for comparing treatment intensity across patients.
- Safety discussions: Large dose changes can be recognized more quickly when converted into one metric.
Conversion factors used in this calculator
This page uses widely referenced, practical conversion estimates often seen in clinical literature and teaching settings. The factors are:
- Immediate-release levodopa × 1.0
- Controlled-release levodopa × 0.75
- Levodopa with entacapone/opicapone add-on effect × 0.33 (applied as extra equivalent)
- Pramipexole × 100
- Ropinirole × 20
- Rotigotine × 30
- Apomorphine × 10
- Bromocriptine × 10
- Rasagiline × 100
- Selegiline × 10
- Amantadine × 1
Different institutions may apply slightly different factors. Always defer to your local protocol if it differs.
How to use this tool correctly
1) Enter total daily dose, not per-tablet dose
If someone takes levodopa 100 mg five times daily, enter 500 mg/day.
2) Use the COMT field carefully
The entacapone/opicapone field is an additional effect. Enter only the levodopa amount paired with COMT inhibitor therapy. The calculator adds 33% equivalent on top of that dose.
3) Interpret the output as an estimate
LEDD is a practical summary number, not a direct dosing recommendation. Real-world effects depend on age, absorption, timing with protein intake, comorbidities, and adverse effects.
Example calculation
Suppose a patient takes:
- IR levodopa: 400 mg/day
- CR levodopa: 200 mg/day
- Levodopa with entacapone: 300 mg/day
- Pramipexole: 1 mg/day
Estimated LEDD:
- IR levodopa: 400 × 1.0 = 400
- CR levodopa: 200 × 0.75 = 150
- COMT add-on: 300 × 0.33 = 99
- Pramipexole: 1 × 100 = 100
Total LEDD ≈ 749 mg/day.
Limitations and clinical cautions
- LEDD is not a substitute for individualized medical judgment.
- Bioavailability can vary between patients and formulations.
- Side effects (hallucinations, dyskinesia, orthostasis, sleep attacks) do not track perfectly with LEDD alone.
- Renal/hepatic function, frailty, and cognitive status may alter prescribing decisions.
Bottom line
A levodopa calculator is a fast, useful way to estimate total dopaminergic treatment intensity. Use it for structure and communication—not as a stand-alone prescribing tool. For any dose adjustment, discuss findings with a qualified clinician.