Learn Hardcore Spanish (Spain): Sin embargo, si no estudio hoy, el suspenso será casi seguro. - However, if I do not study today, failing will be almost certain.

pero is the most common “but” and is usually used inside a sentence, without necessarily starting a new one:
- Quiero salir, pero tengo que estudiar.
sin embargo is closer to “however / nevertheless” and is more often used:
- at the beginning of a sentence, and
- followed by a comma:
  - He salido mucho esta semana. Sin embargo, hoy voy a estudiar.

You could say:

Pero si no estudio hoy, el suspenso será casi seguro.

…but Pero, si no estudio hoy… (with a comma and at the start) feels a bit clumsier and more conversational. Sin embargo sounds a bit more formal and “discourse-like,” clearly connecting this sentence with what came before.

Why is it si no estudio hoy with the present tense, instead of si no estudiaré hoy with the future?

In Spanish, si-clauses referring to real or likely future situations use the present tense, not the future. The pattern is:

si + present indicative, future indicative

So you get:

Si no estudio hoy, el suspenso será casi seguro.
If I don’t study today, the fail will almost certainly happen.

Using a future in the si-clause (si no estudiaré hoy) is ungrammatical in this context. Spanish prefers:

Si estudio, aprobaré. – If I study, I’ll pass.
Si llegas tarde, perderás el tren. – If you arrive late, you’ll miss the train.

So the present estudio in the si part already expresses a future condition.

What exactly does el suspenso mean here? Is it “suspense”?

No. In Spain, suspenso has a special meaning in the education / exams context:

un suspenso = a fail (a failing mark / failing grade)
tener un suspenso en matemáticas = to have a fail in maths

So:

el suspenso será casi seguro ≈ failing (the exam) will be almost certain
Or more naturally: I’ll almost certainly fail.

This is Spain-specific usage. In Latin America, you’re more likely to see:

un reprobado, un desaprobado, or simply the verb:
- Voy a reprobar / desaprobar.

The word suspenso can also mean suspense in other contexts (e.g. in a story), but here the school meaning is clear from context.

Why do we say el suspenso with el? Could we just say suspenso será casi seguro?

You need the article el because suspenso is being used as a countable noun (“the fail / that fail”) in this sentence:

el suspenso = the failing grade / the fact of failing (this exam)

Saying suspenso será casi seguro (without el) sounds wrong in this context; the noun needs the article when you’re talking about a specific fail that you’re expecting.

Compare:

El suspenso fue una sorpresa para todos.
The failing grade was a surprise for everyone.
Tengo miedo al suspenso.
I’m afraid of failing (getting a failing mark).

So: keep el.

Could I use a verb instead of el suspenso? For example: …si no estudio hoy, suspenderé casi seguro?

Yes, that’s very natural:

Sin embargo, si no estudio hoy, suspenderé casi seguro.
However, if I don’t study today, I’ll almost certainly fail.

Differences:

el suspenso será casi seguro
- Uses the noun el suspenso (“the fail”).
- Slightly more detached / nominal: “The failing will be almost certain.”
suspenderé casi seguro
- Uses the verb suspender (“to fail” an exam).
- Feels a bit more direct and personal: “I’ll almost certainly fail.”

Both are good, everyday Spanish in Spain.

Why is it seguro and not segura in casi seguro? Shouldn’t it agree with something?

Here, seguro is an adjective that agrees with el suspenso:

el suspenso → masculine singular
(el suspenso) será casi seguro → seguro is masculine singular too.

So the sentence is literally:

El suspenso será casi (completamente) seguro.
The fail will be almost completely certain.

If the subject were feminine, you’d change it:

La derrota será casi segura. – The defeat will be almost certain.
La suspensión será casi segura. – The suspension will be almost certain.

In many fixed expressions like es seguro, es casi seguro, seguro que, seguro, people don’t think about agreement consciously, but here grammatically it matches el suspenso.

What does casi seguro mean exactly? Is it like “probably”?

casi seguro literally means “almost certain”.

In practice, it’s close to English “almost certainly / pretty much for sure / very probably”.

Nuance compared to other options:

probablemente – probably (neutral)
casi seguro – almost certain (sounds a bit stronger than probablemente)
seguro / seguramente – can mean “surely / almost certainly”, but in conversation they’re often a bit looser in practice.

Examples:

Va a llover, casi seguro. – It’s almost certainly going to rain.
Si llegas tarde, casi seguro que no entras. – If you arrive late, you almost certainly won’t get in.

In the sentence:

el suspenso será casi seguro ≈ failing will be almost certain / a near certainty.

Can I change the word order, like Sin embargo, el suspenso será casi seguro si no estudio hoy?

Yes. Both are correct:

Sin embargo, si no estudio hoy, el suspenso será casi seguro.
Sin embargo, el suspenso será casi seguro si no estudio hoy.

The difference is focus:

Version 1 starts with the condition (“if I don’t study today”), stressing the cause.
Version 2 starts with the consequence (“the fail will be almost certain”), then gives the reason.

Native speakers use both orders freely. Commas help chunk the sentence and make it clearer:

With a fronted si-clause, a comma after it is standard:
- Si no estudio hoy, suspenderé.

Why is there a comma after Sin embargo? Is it always like that?

Yes, in standard Spanish sin embargo used as a connector at the start of a sentence is normally followed by a comma:

Sin embargo, no puedo ir.
Sin embargo, si no estudio hoy, el suspenso será casi seguro.

It works like English “However, …” at the beginning of a sentence.

Inside a sentence, you might also set it off with commas:

He estudiado mucho; sin embargo, sigo preocupado.

So: Sin embargo, + comma is what you want here.

Could I say si hoy no estudio instead of si no estudio hoy? Does it change the meaning?

You can say both, and the meaning is practically the same:

Si no estudio hoy, el suspenso será casi seguro.
Si hoy no estudio, el suspenso será casi seguro.

Difference:

si no estudio hoy – the negation (“don’t study”) comes earlier.
si hoy no estudio – puts a bit more emphasis on “today”.

It’s a very subtle nuance. Both are completely natural.

Why isn’t it si no estoy estudiando hoy (present continuous), like English “if I’m not studying today”?

Spanish uses the simple present much more often than English, especially for future plans and conditions.

Compare:

English: If I’m not studying today, I’ll fail.
Spanish: Si no estudio hoy, el suspenso será casi seguro.

The present continuous (estar + gerundio) in Spanish is usually for ongoing actions right now:

Estoy estudiando ahora. – I’m studying right now.
Si no estoy estudiando cuando llegues, salimos.
If I’m not studying when you arrive, we’ll go out.

In your sentence, you’re talking about whether you study at some point today, not about what you’re doing at a precise moment, so simple present (estudio) is the natural choice.