Following are some of the common ways of expressing approximations in Spanish. Although English equivalents are listed, keep in mind that nearly all of these terms except for casi/"almost" are synonymous, so when translating to English you should translate on the basis of context and meaning rather than always using the word listed as the literal equivalent.
aproximadamente approximately El diccionario ofrece traducciones de aproximadamente 5.500 términos. The dictionary provides translations of approximately 5,500 terms.
como (more common in Latin America) about Estuve malo como cuatro meses. I was sick for about four months.
más o menos more or less He perdido, más o menos, seis kilos y en muy poco tiempo. I have lost more or less six kilograms and in very little time.
a eso de (used most commonly with times) about A eso de las 16:00 la clínica estará abierta. The clinic will be open about 4 p.m.
casi almost Casi 3 de cada 100 emails enviados en España este año contenía virus. Almost 3 out of each 100 email letters sent in Spain this year included a virus.
cerca de close to México tiene cerca de 10 millones de internautas. Mexico has close to 10 million Internet users
alrededor de around Alrededor de una docena de referencias citadas en el trabajo no aparecen en la bibliografía. Around a dozen references cited in the work don't appear in the bibliography.
unos, unas some Costó unos 5.000 pesos. It cost some 5,000 pesos.
o así or so Has jugado al juego "teléfono"? Reúnes una docena de gente o así en un círculo y la primera persona le susurra un mensaje al segundo. Have you played the game "telephone"? You bring together a dozen people or so and the first person whispers a message to the second.

