Too much
Means 'a lot' or 'much', but can imply 'too much' depending on context and tone. For example, if someone offers you more food, saying 'Es mucho' means 'That's a lot' (implying it's too much for you).
A more formal word that means 'excessive'. It's a direct cognate and easy to recognize. Use it when you want to be more emphatic or formal.
A very common, informal phrase meaning 'a ton' or 'a heap'. It's used to express a large, often overwhelming, quantity.
The coffee has too much sugar for me.
There are too many people in the store.
No thank you, that's too much food.
I have a ton of (too much) work today.
'Demasiado' is the universal standard. Informal expressions like 'un montón' are also widely understood.
'Demasiado' is standard. In very informal slang, you might hear 'un chorro' to mean 'a ton' or 'a lot', implying an excessive amount.
'Demasiado' is the main word. Informally, 'un pocotón' is a common and colorful way to say 'a huge amount'.
While 'demasiado' is standard, 'un montón' is extremely common in everyday conversation.
'Demasiado' is the standard term, just as in Latin America. 'Un montón' is also frequently used in casual settings.
Confusing 'mucho' and 'demasiado'. — 'Mucho' means 'a lot', which is neutral or positive. 'Demasiado' means 'too much', which implies an excess and is often negative. For example: 'Me gusta mucho' (I like it a lot) vs. 'Es demasiado' (It's too much).
Forgetting to change the ending for gender and number. — 'Demasiado' must match the noun it describes. Use 'demasiado' for masculine singular (demasiado ruido), 'demasiada' for feminine singular (demasiada comida), 'demasiados' for masculine plural (demasiados carros), and 'demasiadas' for feminine plural (demasiadas cosas). A common error is saying 'demasiado gente' instead of the correct 'demasiada gente'.
Using 'demasiado' when it follows a verb. — When 'too much' modifies a verb, the form 'demasiado' does not change. For example, 'Tú hablas demasiado' (You talk too much) or 'Ellos comen demasiado' (They eat too much). You don't change the ending in these cases.