Pesar vs. sopesar
While both words relate to the concept of weight, pesar focuses on the objective measurement or state of being heavy, whereas sopesar focuses on the action of estimating weight by handling an object or mentally evaluating options.
Pesar
A2This verb is used when you determine the exact weight of something using a scale. It is also used to state how heavy a person or object is. Figuratively, pesar can express that something has a strong influence or causes a feeling of burden.
Tengo que pesar la maleta antes de ir al aeropuerto.
(I have to weigh the suitcase before going to the airport.)
El bebé pesa cinco kilos.
(The baby weighs five kilos.)
La cajera va a pesar las manzanas en la balanza.
(The cashier is going to weigh the apples on the scale.)
Su opinión pesa mucho en la decisión final.
(His opinion weighs heavily on the final decision.)
Sopesar
B2This verb describes the action of lifting something with your hands to estimate how heavy it is without using a scale. In a figurative and very common sense, sopesar means to consider the pros and cons of a situation carefully before making a decision.
Ella sopesó la carta en su mano, tratando de adivinar qué había dentro.
(She weighed the letter in her hand, trying to guess what was inside.)
Debemos sopesar todas las opciones antes de invertir el dinero.
(We must weigh all the options before investing the money.)
El constructor levantó el ladrillo para sopesarlo.
(The builder picked up the brick to weigh it in his hand.)
Estuvimos sopesando los riesgos del proyecto durante la reunión.
(We were weighing the risks of the project during the meeting.)
Summary
Use pesar when you are measuring an exact weight with a tool or stating a fact about heaviness. Use sopesar when you are physically lifting something to guess its weight or mentally balancing advantages and disadvantages.