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Are passive voice sentences really harder to read?  I hear this a lot as a reason to not use, or to at least use sparingly, the passive voice in writing.  So I decided to do a little test.  I took a series of sentences and wrote them in both the passive and active voice.  I then checked their readability statistics using Microsoft Word’s native tool for this.

Example 1: 

Active: “I mailed the letter.”

Flesch Reading Ease: 97

Flesch-Kincade Grade Level: 0.7

Passive: “The letter was mailed by me.”

Flesch Reading Ease: 100

Flesch-Kincade Grade Level: 0.5

Example 2:

Active: “My father gave me this sword.”

Flesch Reading Ease: 100

Flesch-Kincade Grade Level: 0.6

Passive: “This sword was given to me by my father.”

Flesch Reading Ease: 94.3

Flesch-Kincade Grade Level: 2.3

Example 3:

“The light from the lantern cast shadows on the walls.”

Flesch Reading Ease: 95.1

Flesch-Kincade Grade Level: 2.4

“Shadows were cast on the walls from the lantern’s light.”

Flesch Reading Ease: 95.1

Flesch-Kincade Grade Level: 2.4

Example 4:

Active: “At each joust, the Queen’s champion fought at least one man who had offended her honor.”

Flesch Reading Ease: 79.5

Flesch-Kincade Grade Level: 6.1

Passive: “At each joust, at least one man who offended the Queen’s honor was fought by her champion.”

Flesch Reading Ease: 80

Flesch-Kincade Grade Level: 6.3

As you can see from these examples, only in one instance (Example 2) is the passive voice version of the sentence significantly “harder” to read on a Flesch-Kincade Grade Level or Flesch Reading Ease scale.  Even so, based on the Flesch Reading Ease scale, both versions of this example are easily read by an average 11-year-old.

Flesch-Kincade Grade Level is an attempt to relate readability to grade level.

Per Wikipedia, Flesch Reading Ease can be interpreted as follows:

http://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_test

So, any sentence scoring 60 or better is easily understood by a typical 15 year old.  In fact, let’s look at the passive voice sentence that I just used:

“Even so, based on the Flesch Reading Ease scale, both versions are easily read by an average 11-year-old.”

Flesch Reading Ease: 62.8

Flesch-Kincade Grade Level: 9.2

I believe that you can see that what makes sentences harder to read, in general, is not using the passive voice instead of the active voice.  Rather, the major factor is really the sentence’s length and the use/non-use of internal punctuations.

Let’s look at that, shall we?

Both of these passages are active voice:

“An old man, he looked like he was only a few minutes away from death.”

Flesch Reading Ease: 90

Flesch-Kincade Grade Level: 4.4

“He was an old man.  He looked like he was only a few minutes away from death.”

Flesch Reading Ease: 98.6

Flesch-Kincade Grade Level: 1.6

Simply using a comma to splice together two sentences has quite an effect on readability.  Quite a bit more than any of the passive/active voice examples I previously used.  Just making it one sentence with a comma, rather than two separate ones, raises the reading level almost three whole grade levels.

Of course, a clumsily constructed passive voice sentence will be hard to read.  But if we are talking about properly constructed sentences, we can see that it is not significantly harder to read than writing that is in the active voice.

Just for the sake of disclosure, the readability statistics on this article are:

Passive Voice Sentences: 6%

Flesch Reading Ease: 69.6

Flesch-Kincade Grade Level: 7.1

That means you’re average 15-year-old can understand it.