The two peaks marked F1 and F2 in the diagram above are the first two formants for a vowel in the region of cardinal 1 [i]. The table below gives typical values in Hz of F1 and F2 for the monophthongal vowels of RP English for adult male speakers.
| Vowel | F1 | F2 |
| i: | 300 | 2300 |
| I | 360 | 2100 |
| e | 570 | 1970 |
| { | 750 | 1750 |
| A: | 680 | 1100 |
| Q | 600 | 900 |
| O: | 450 | 740 |
| U | 380 | 950 |
| u: | 300 | 940 |
| V | 720 | 1240 |
| 3: | 580 | 1380 |
The diagram below shows the general relationship between the frequencies of F1 and F2 and the vowel space represented by the traditional vowel quadrilateral.
