Grimm's Law (First Consonant Shift)

First Stage	.
/bh/ (voiced bilabial aspirate)	became	/b/ (voiced bilabial fricative)
/dh/ (voiced alveolar aspirate)	became	/ð/ (voiced interdental fricative)
/gh/ (voiced velar aspirate)	became	/g/ (voiced velar fricative)
.
Second Stage	.
/p/ (voiceless bilabial stop)	became	/f/ (voiceless labio-dental fricative)
/t/ (voicless alveolar stop)	became	/q/ (voiceless interdental fricative)
/k/ (voicless velar stop)	became	/h/ (voiceless velar fricative)
Third Stage	.
/b/ (voiced bilabial stop)	became	/p/ (voiceless bilabial stop)
/d/ (voiced alveolar stop)	became	/t/ (voiceless alveolar stop)
/g/ (voiced velar stop)	became	/k/ (voiceless velar stop)
.
Fourth Stage	.
/b/ (voiced bilabial fricative)	became	/b/ (voiced bilabial stop)
/ð/ (voiced interdental fricative)	became	/d/ (voiced alveolar stop)
/g/ (voiced velar fricative)	became	/g/ (voiced velar stop)

Grimm's Law does not apply to *IE voiceless stops (that is, /p/, /t/, /k/) following another voiceless stop or /s/. See also Verner's Law.