The regular comparative is almost identical to the English one:
The regular form
frisch > frischer
fresh > fresher
klein > kleiner
small > smaller
There’s also a few things to be aware of and there are only few irregular forms.
groß > größer -------- After o,u,a you often need to add an Umlaut to the comparative
big > bigger
lang > länger
long > longer
teuer > teurer -------- The form with ‘more + adjective’ does not exist in German
expensive > more expensive
müde > müder -------- At times the -e is sacrificed in the comparative
tired > more tired
The most relevant irregular forms
gut > besser
viel > mehr
gern > lieber
hoch > höher
nah > näher
Usage
Klaus: 1,60m 1. Klaus ist groß.
Paul: 1,80m 2. Paul ist größer als Klaus.
Frank: 1,90m
With the comparative we use two add-ons:
In case the things/persons that we compare are different from eachother we use als.
In case they are equal in regards to the compared characteristic, we use (genau) so groß wie and Never (genau) so größer wie. So you’d have to say:
Paul ist genauso groß wie Hans.
One more thing
When these forms function as adjectives, they take the ending according to the rules of adjective declination, which will be covered later on. Just take notice for now. It will come to you after you have dealt with the adjectives.:
Hier ist ein frischerer Apfel.
Hier ist ein kleineres Messer.
This topic is covered in: A2-L42 and A2-L44.