Tener que vs poder
Having to do something and being able to do it are different.
The short answer
Tener que + infinitive expresses a necessity or obligation in these everyday patterns. Poder + infinitive expresses ability, possibility or permission. Tengo que salir means “I have to leave”; puedo salir means “I can leave”.
tener que
A necessity
An action that needs to happen.
Tengo que salir.
I have to leave.
poder
An ability or possibility
An action that is possible or permitted.
Puedo salir.
I can leave.
Keep the action, change the message
Imagine leaving work. One sentence says a commitment requires you to leave; the other says your circumstances allow it. Only tener needs que before the infinitive. Poder connects directly to the action.
Tenemos que salir a las seis.
We have to leave at six.
The time is a requirement.
Podemos salir a las seis.
We can leave at six.
The time is an available possibility.
“Don’t have to” does not mean “can’t”
Negation is where this contrast becomes especially useful. No tener que usually removes a necessity. No poder indicates that the action is not possible or not allowed; the situation tells you which meaning is intended.
No tienes que entrar ahora.
You don’t have to enter now.
Entering now is not required.
No puedes entrar ahora.
You can’t enter now.
There may be a restriction or a practical obstacle.
Try it yourself
Choose the word or verb form that fits the situation. Say the complete sentence before checking your answer.
Complete the pattern for “I have to study”.
Tengo ___ estudiar.
Check answer 1
Tengo que estudiar.
Tener needs que before the infinitive in this construction.
Use the yo form of poder to ask permission to enter.
¿___ entrar?
Check answer 2
¿Puedo entrar?
Puedo + infinitive can ask for permission.
Tell one person informally that payment today is not necessary. Use tener.
No ___ que pagar hoy.
Check answer 3
No tienes que pagar hoy.
No tienes que removes the requirement; it does not itself forbid payment.
Make it your own
Say one thing you have to do, one you can do, and one you don’t have to do. Keep the same action once to hear how the meaning changes.
Grammar references
For further detail, see these Spanish-language dictionary and usage entries. Examples and practice questions above are written for this guide.