There are 16 7-letter words that start with 'mag'.
| magalog | magenta | maggots | maggoty | 
| magians | magical | magilps | maglevs | 
| magmata | magnate | magneto | magnets | 
| magnify | magnums | magpies | magueys | 
Note: These 16 7-letter words that start with 'mag' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with magn, magi, maga, magd, mage, magm, magg, magu, magl, mago, magp, mags.
4-letter words start with 'mag' (3)