The short answer
Residential programs commonly run 30, 60 or 90 days. Detox is usually a matter of days. PHP, IOP and outpatient care can last weeks to months. NIDA says people move through treatment at different rates, so there’s no set length.
Why 30 days is so common
Thirty days is a habit and a billing pattern more than a medical rule. What matters is what’s planned next. A short stay followed by months of outpatient care can be a real plan. A long stay with nothing after it may not be.
Sources
This is general information, not medical advice. Talk to a doctor about your own situation.
Frequently asked questions
How many days do you stay in rehab?
Often 30, 60 or 90 for residential care. Ask the program how it decides.
How long is detox?
Often days rather than weeks, though it depends on the substance and the person.
Can I leave early?
Adults in voluntary care can usually leave. Ask about any costs first.
Is a longer stay always better?
Not always. Staying engaged in care over time matters more than one long stay.