Tengo calor.

In Spanish, many physical sensations are expressed with tener (to have), not estar (to be).

So Spanish says:

• Tengo calor = literally I have heat
• Tengo frío = I’m cold
• Tengo hambre = I’m hungry
• Tengo sed = I’m thirsty

So estoy calor is not correct.

Usually, no—not if you just mean you feel warm.

For a person, estoy caliente often means I’m sexually aroused, so learners should be very careful with it.

If you want to say you feel hot, use:

• Tengo calor

But caliente is fine for things:

• El café está caliente = The coffee is hot
• La sopa está caliente = The soup is hot

Because in this expression, Spanish normally just says tener + noun without an article.

So:

• Tengo calor
• Tengo frío
• Tengo hambre
• Tengo sueño

You do not normally say:

• Tengo el calor
• Tengo un calor
  unless you are using a different, more specific meaning in a special context.

The basic expression is simply tener calor.

Tengo is the first person singular present tense of tener.

So:

• tener = to have
• tengo = I have

That means:

• Tengo calor = literally I have heat

Related forms:

• tienes calor = you are hot
• tiene calor = he/she is hot
• tenemos calor = we are hot

Usually, no.

Spanish often leaves out subject pronouns because the verb already shows who the subject is.

So the normal sentence is:

• Tengo calor

You can add yo for emphasis or contrast:

• Yo tengo calor, pero ella no. = I’m hot, but she isn’t.

But in most situations, just tengo calor is the natural choice.

This is a very common and important difference:

• Tengo calor = I feel hot
• Hace calor = It’s hot / The weather is hot

Examples:

• Tengo calor porque he caminado mucho. = I’m hot because I’ve walked a lot.
• Hace calor en Sevilla en verano. = It’s hot in Seville in summer.

So:

• tener calor = a person’s sensation
• hacer calor = general temperature / weather

Calor is generally treated as a masculine noun:

• el calor

In tengo calor, you do not see the article, so the gender is not obvious there. But it matters in other contexts:

• El calor es insoportable. = The heat is unbearable.
• Mucho calor = a lot of heat

For basic use, just remember the full expression:

• tener calor

Very simply:

Negative

• No tengo calor. = I’m not hot.

Question

• ¿Tienes calor? = Are you hot?
• ¿Tenéis calor? = Are you hot? (plural, used in Spain)

You can also answer:

• Sí, tengo calor.
• No, no tengo calor.

A common way is to add mucho:

• Tengo mucho calor. = I’m very hot / I’m really hot

Other natural options:

• Tengo muchísimo calor. = I’m बेहद hot / I’m extremely hot
• Tengo un calor terrible. = I’m terribly hot

The most basic and useful one is:

• Tengo mucho calor

A simple guide:

• tengo sounds roughly like TEN-go
• calor sounds roughly like ka-LOR

Stress:

• TEN-go ka-LOR

In standard Peninsular Spanish:

• the g in tengo is a hard g
• the r in calor is a soft tapped r
• the final r is pronounced, not silent

A rough English-style approximation is:

• TEN-go ka-LOR

Yes. This pattern is very common in Spanish for physical states and needs.

Some useful ones:

• Tengo frío. = I’m cold.
• Tengo hambre. = I’m hungry.
• Tengo sed. = I’m thirsty.
• Tengo sueño. = I’m sleepy.
• Tengo miedo. = I’m afraid.

So tengo calor is part of a larger pattern: Spanish often uses tener where English uses to be.