Why Use “Tengo que” Instead of “Debo” in Spanish?

Have you ever wondered why we say “tengo que estudiar” and not just “debo estudiar”? Although both phrases seem similar, they carry a powerful nuance. And if you’re learning Spanish, understanding this can transform how you speak. Welcome to the linguistic duel: tengo que vs debo.

Two sides of the same coin: external vs internal obligation

Let’s imagine something simple: your boss sends you an urgent message. You say, “Tengo que responderle ahora mismo” / “I have to reply right now.” Could you say “Debo responderle ahora mismo” instead? Yes. But something changes.

“Tengo que” reflects an obligation coming from the outside—external pressure.

For example:

• Tengo que ir al médico porque me dieron cita hoy.
  I have to go to the doctor because I got an appointment today.

• Tengo que estudiar, hay examen mañana.
  I have to study, there's an exam tomorrow.

On the other hand, “debo” points inward. It’s used when you yourself decide what’s right or necessary:

• Debo decir la verdad, aunque duela.
  I must tell the truth, even if it hurts.

• Debo empezar a comer mejor.
  I must start eating better.

Important: Although the general rule is this, you can also use “debo” for external obligations when they’re understood as variable, ethical, or moral duties.

For example:

Debo ir a la reunión, aunque no es obligatoria.
(I should go to the meeting, even if it’s not mandatory — you decide based on social or personal convention.)

Here’s the key takeaway: tengo que vs debo isn’t just a matter of words. It’s a way of showing who or what is in charge—yourself, or the world around you?

Which one is more common? A look at real life

According to linguistic studies and analysis from CREA (Corpus de Referencia del Español Actual), “tengo que” is used more than twice as often as “debo” in most Spanish-speaking countries. Why? Because we’re surrounded by external obligations—jobs, schedules, rules, commitments.

Common examples:

• Tengo que salir ya o pierdo el tren.
  I have to leave now or I’ll miss the train.

• Debo admitir que estaba equivocado.
  I must admit I was wrong.

While both express obligation in Spanish, their tone and frequency of use are different. In short: to sound more natural, use “tengo que”. To sound more serious or moral, go with “debo”.

Tip

See the difference? The verb “tener que” always includes the -que- particle after the conjugated verb. In contrast, “deber” is used on its own, without -que-:

• Tengo que estudiar. → I have to study.

• Debo estudiar. → I must study.

And although they can often be interchanged, choosing the right one will make your Spanish shine.

Culture, emotion, and intention: what your words reveal

Spanish is pure emotion. In Spanish-speaking cultures, the words you choose convey more than just a message. With tengo que vs debo, you reveal how you feel about what you’re saying.

For example:

• Tengo que hacerlo, aunque no quiera.
  I have to do it, even if I don’t want to. → Obligation, unavoidable.

• Debo hacerlo, porque creo que es lo correcto.
  I must do it, because I believe it’s the right thing to do. → Personal, conscious choice.

There are also other ways to express obligation in Spanish, such as:

• Hay que practicar todos los días.
  One must practice every day. (impersonal)

• Tendría que pensarlo bien.
  I’d have to think it over. (conditional)

The language offers many ways to say the same thing, but each one has its own soul. Tengo que vs debo isn’t just about vocabulary—it’s about nuance, emotion, and intention.

Master the meaning, not just the grammar

It’s not just about speaking correctly—it’s about choosing the words that truly express what you mean. That’s why knowing when to use tengo que vs debo gives you power. The power to sound authentic. The power to connect more deeply with others. The power to express obligation in Spanish with clarity and purpose.

So the next time you’re choosing between one or the other, listen to your intuition… Is the world demanding it, or is your heart asking for it?

And if you still feel like you need more practice, we’re here for you. This journey isn’t one you have to take alone. At WorldsAcross, we’ll guide you every step of the way—teaching you not just how to speak Spanish, but how to feel it.