The phrase "about six kilometers" is correct and usable in written English.
It can be used when providing an approximate distance in a variety of contexts, such as travel, navigation, or geographical descriptions.
Example: "The nearest gas station is about six kilometers from here."
Alternatives: "approximately six kilometers" or "roughly six kilometers".
The city center is about six kilometers (3.73 miles) away; Dublin airport is 20 kilometers (12.4 miles) away.
"We had clear information that the Taliban had seized the fuel trucks about six kilometers away from our base in order to launch an attack against our soldiers in Kunduz," he told the newspaper Bild am Sonntag.
I applied it to the Jerusalem tracks, and discovered that the animal, assuming it was a dinosaur, was going about six kilometers (3.72 miles) an hour — Roman army marching speed.
Take the S.P. 14 from Syracuse to Canicattini Bagni; from the traffic light drive about six kilometers, look for a fork on the left with a sign for Limoneto.
Last Thursday, the funeral of Pascal Linguet was held here in Rilhac-Rancon, a town of over 4,000 people surrounded by wooded rolling hills about six kilometers, or four miles, north of Limoges.
And Alila Hotels & Resorts, a luxury brand based in Singapore, is planning to introduce in 2015 a hotel and resort project on Koh Russey, about six kilometers from the mainland.
In fact, I attended a conference on mazar in August 2008, about ten kilometers from the incident in Lukchun, at the Tuyuq mazar (my photograph of the site is above).
The breakaway began with about seven kilometers to go.
Every morning, Mrs. Khan wakes up before dawn and walks about four kilometers (2.5 miles) to work.
They traveled at a speed of about three kilometers a day.
It kept swarming at Hamilton, McCartney and Pauwels, eventually swallowing them with about three kilometers to go.
