Nielsen TV ratings are merely percentages of whatever is being measured. Sometimes it gets confusing because so many different things are measured.
If you see a 3.4 national adults 18-49 rating, that doesn't mean 3.4 million adults 18-49, it just means 3.4 percent of the 127,860,000 adults 18-49 in the United States (down from 131,490,000 last season) who live in a household with a television were watching based on the Nielsen estimates for the 2011-12 television season.
So a 3.4 adults 18-49 rating works out to be around 4.35 million adults 18-49.
Here are some of the ratings slices we frequently post data for and the total size of the populations being measured.
Now updated for the 2011-12 season:
| Nielsen Estimates* | Population | A 1.0 Rating Equals |
| Households | 114.7 Million | 1.147 Million |
| Adults 18-49 | 127.86 Million | 1.279 Million |
| Women 18-49 | 64.02 Million | 640,200 |
| Men 18-49 | 63.84 Million | 638,400 |
| Adults 18-34 | 67.59 Million | 675,900 |
| Women 18-34 | 33.55 Million | 335,500 |
| Men 18-34 | 34.04 Million | 340,400 |
| Adults 25-54 | 120.68 Million | 1.207 Million |
| Teens 12-17 | 24.04 Million | 240,400 |
| Kids 2-11 | 41.18 Million | 411,800 |
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I didn't add it to the list above, but there are 289.70 million (down from 294.65 last season) potential "total viewers" in the U.S. age 2+ in households with TVs according to the estimates for the 2011-12 season.
