Use the apostrophe for feet: 5′
Use the double quotation mark for inches: 8″
Write both together as 5′ 8″
For fractions, write 5′ 8 1/2″
For a range, write 5′ 8″–6′ 0″
In plain text, you can also write 5 ft 8 in
In formal writing, keep the symbols close to the numbers with a space between feet and inches: 5′ 8″
Do not use a prime symbol for inches and a double prime symbol for feet
For exact measurements, include the inch mark after the inches value: 6′ 2″
For zero inches, write 6′ 0″