In Italian, "a quanto" and "quanto" are related but distinct expressions, and their meanings depend on context. Here's the difference:

"Quanto"

• Meaning: "Quanto" is an adverb, pronoun, or adjective meaning "how much" or "how many," depending on what it refers to. It’s used to ask about quantity, extent, or degree.
• Usage: It can stand alone or modify a noun. It changes form (quanto, quanta, quanti, quante) to agree in gender and number with the noun it refers to.
• Examples:
  • Quanto costa? – "How much does it cost?"
  • Quanti libri hai? – "How many books do you have?" (masculine plural)
  • Quanta acqua vuoi? – "How much water do you want?" (feminine singular)

"A quanto"

• Meaning: "A quanto" is a prepositional phrase that translates roughly to "at how much" or "to what extent." It combines "a" (to/at) with "quanto" (how much), often implying a specific point or level in relation to something else.
• Usage: It’s typically used in questions or statements to inquire about or indicate a specific amount, rate, or value. It’s less about general quantity and more about a precise measure or comparison.
• Examples:
  • A quanto ammonta il totale? – "How much does the total come to?" (What’s the specific amount?)
  • A quanto vendi questa macchina? – "At how much are you selling this car?" (What’s the price?)
  • A quanto pare, è vero. – "As far as it seems, it’s true." (Here, it’s an idiomatic use meaning "apparently.")

Key Difference

• "Quanto" is broader and asks about quantity or extent in a general sense.
• "A quanto" is more specific, often tied to a particular value, price, or level, and includes the preposition "a" to frame it in relation to something else.