Your letter of interest shouldn’t use up any more than one A4 page (Arial, 12-point font). This includes your contact information, headers, greetings, and salutations. You’ll also want to split your letter into 3 or 4 paragraphs, depending on the topics you’d like to cover. If your cover takes more than 5 minutes to read at a normal pace, it’s probably too long, and you’ll risk losing the reader’s attention.