If you want to get from Peru to Chile by road, you need to reach Tacna first. Tacna is a commercial town, located only 35 kilometers away from the border with Chile. We came to Tacna from Arequipa, it is easy, you have buses all day long, the ride takes from 6 to 7 hours, we paid S20 (6$;5,4€). We also saw direct buses from other places in Peru (Lake Titicaca, Cusco) so I think it’s really easy to get from Peru to Chile by road, also the border crossing was one of the fastest and easiest on our trip.
Once in Tacna you have 2 options, you can spend the night there (this what we did) and continue early next morning, or you can go to the international terminal (just across the street from the terminal that you arrive at) and continue to Chile the same day.
Next day we woke up early and headed to the international terminal. We took a bus from the town, you can also walk, it is around 30 to 40 minutes walk.
Take a bus
Once we reached the terminal, we asked around for buses to Arica (bus a Arica?), they cost S12 (3,6$;3,2€), you buy the ticket on the bus. Don’t forget to pay the departure tax (ticket de embarque), it cost S2 (0,6$;0,54€). The bus driver will take your passport (we didn’t like that) and give it back to you at the border, you will also get the immigration form to fill. The ride all together takes around 40 minutes, they stop at the border, wait that everybody gets an exit and entry stamp and then you continue to Arica. The bus will be full of local ladies, toilet paper, plastic cups, plates and so on. Apparently, stuff in Peru cost much less than in Chile so it worth to cross the border and make a supply. After the border the bus stops every minute or so, people getting out with all the new stuff they bought, so if you are short of time, maybe a collectivo is a better option for you.
Take a collectivo
If you are short in time and for more comfortable border crossing, I recommend you take a collectivo (shared taxi). They depart from the same terminal, and they cost S20 (6$;5,3€) per person. Cause you don’t need to wait for all the bus to get the stamps will be much faster and also much more comfortable.
Peru Chile border crossing
Border crossing is easy, very well organized, for me the favorite border crossing from all of our trip. When you get off the bus or out of the taxi, you need to bring your big backpack with you, cause after they stamp your passport, you need to do the bag check (similar than at the airports), everything goes very smooth and fast. You will also see dogs at the border but they are not trained for drugs but for organic products, Chile is very strict about that, you can bring none. Don’t forget to save the entry card! I didn’t see any money exchange places at the border but it was really easy to withdrawal money at Arica bus terminal, they have an ATM there.