Enter your weight for an evidence-based single-dose range, the practical ceiling, and safer redosing - with a summary you can copy or screenshot. It uses the same body-weight guidance as our full dosing guide.
A starting point for people who have already decided to use - not a recommendation to. It only means anything once you have tested your substance and can weigh it accurately.
Why these numbers
The dose-response curve is not a straight line. Past a fairly low ceiling, more MDMA mostly adds jaw clenching, overheating, anxiety and a worse comedown - not more of the good part. The calculator scales to roughly 1.5 mg per kg for a standard dose and about 1 mg/kg for a first time, and caps everything at a practical 120 mg, because a heavier body earns more load, not more euphoria.
Redosing gets a lighter touch on purpose: the second dose never recaptures the first and deepens the crash, so the tool suggests at most one booster of about half the first dose, keeping the night under roughly 2 mg/kg. For the full reasoning, the failure modes and the evidence, read the complete dosing guide.