Necesitar vs. requerir vs. precisar

The Spanish words 'necesitar', 'requerir', and 'precisar' all translate roughly to 'to need' or 'to be in need of' in English, but they are used in slightly different contexts and with different nuances. Here we highlight their differences through examples.

Necesitar

'Necesitar' is the most common and general way to say 'to need'. It often implies a necessity or essential requirement for someone or something.
Necesito agua.
(I need water.)
Ella necesita ayuda con su tarea.
(She needs help with her homework.)
Necesitamos terminar este proyecto.
(We need to finish this project.)

Requerir

'Requerir' means 'to require' and is often used in more formal contexts. It implies that something is required by circumstances or regulations. Often used in official, technical, or specific requirements contexts.
Este trabajo requiere experiencia previa.
(This job requires previous experience.)
El reglamento requiere que uses casco.
(The regulation requires you to wear a helmet.)
La situación requiere una respuesta rápida.
(The situation requires a quick response.)

Precisar

'Precisar' also means 'to need' but is less commonly used in everyday speech compared to 'necesitar'. It can imply needing something specific or precise, and it is also used to mean 'to specify'.
Preciso de tu consejo en este asunto.
(I need your advice on this matter.)
El mecánico precisó las piezas necesarias para la reparación.
(The mechanic specified the necessary parts for the repair.)
Esta receta precisa ingredientes frescos.
(This recipe needs fresh ingredients.)

Summary

In summary, while all three verbs relate to the concept of needing something, they each have unique nuances. 'Necesitar' is the most commonly used and general term. 'Requerir' has a more formal tone, often used in official or technical contexts indicating requirements by rules or circumstances. 'Precisar' suggests needing something specific and can also mean to specify something clearly.