Is the word calma the same in Brazilian and European Portuguese?

Yes.

The word "calma" is identical in meaning, spelling, and grammatical function in both Brazilian and Continental Portuguese. It can function as a noun (meaning tranquility or peace) or as an interjection (a command to relax or slow down). The only difference is in pronunciation: Brazilian Portuguese features more open, clearly articulated vowels and a syllable-timed rhythm, whereas Continental Portuguese features more closed, reduced, or "swallowed" vowels, especially in unstressed syllables, resulting in a more stress-timed rhythm.

Brazilian Portuguese Examples

1. Calma, tudo vai dar certo. (Calm down, everything will work out.)
2. Calma aí, eu não entendi nada do que você disse. (Hold on, I didn't understand anything of what you said.)
3. Ele precisa de um pouco de calma para tomar uma decisão. (He needs a bit of calm to make a decision.)
4. Vamos com calma para não cometer erros. (Let's take it easy so as not to make mistakes.)
5. Fica calma, vai passar logo. (Stay calm, it will pass soon.)

Continental Portuguese Examples

1. Calma, tudo se vai resolver. (Calm down, everything will be resolved.)
2. Calma lá, eu não percebi nada do que disseste. (Hold on, I didn't understand anything of what you said.)
3. Ele precisa de alguma calma para tomar uma decisão. (He needs some calm to make a decision.)
4. Vamos com calma para não cometer erros. (Let's take it easy so as not to make mistakes.)
5. Tem calma, vai passar logo. (Be calm, it will pass soon.)