Formatting Rules

Improve letter readability and comprehension by using these formatting rules, based on typography and design studies.

  • Black text only. Other text colors reduce comprehension by 30 to 90 percent.
  • Use a serif font for body text. Sans serif fonts reduce body text comprehension by a factor of up to five (but san serif type doesn’t reduce headline readability).
  • Use one of the following type size/leading combinations: 10/12, 11/12, 11/13, 12/13.  They all get over 90 percent comprehension.
  • Spot color increases initial attention to the letter by up to 80 percent, but use it only in non-text elements.
  • Never use reversed type: readability is reduced by a factor of five or more.
  • Never use more than a 10 percent tint behind black text.  Color text on a color background reduces comprehension to near zero.
  • Jumps and cutoffs annoy 70 to 80 percent of readers, but widows, orphans, and bastard measure don’t affect readership.
  • Keep body measure to between 20 and 60 characters.
  • Long and multi-deck headlines reduce readership.
  • Compared to lower case, ALL CAPS headlines reduce perceived legibility by 30 percent.
  • Compared to fully justified text, ragged right reduces comprehension by 50 percent and ragged left by 80 percent in brochures and ads.  In letters, stick with left justified.
  • Display items like pictures work to increase attention without reducing readership when placed at the upper right top and middle left center.
  • Have a compelling story or need to explain a special project that requires more than one page? Don’t shrink or squeeze the text; go ahead and continue onto the back of the page. Underlining, bolding of key phrases, and paragraph headings will lead the reader through a two-page letter.
  • Acquisition letters may need to be longer so that prospects will have enough information to decide whether they’ll join your organization or make a gift.
  • Always take one last look and ask yourself: “Have I made this letter as easy to read as possible?”  Use our handy check list to evaluate your letter design.