dan or als? A quick rule for comparisons

When you compare two things in Dutch, the linking word is either dan or als. The choice depends on the kind of comparison: Hij is groter dan ik (He is taller than I) uses dan, but Hij is even groot als ik (He is as tall as I) uses als.

Use dan after a comparative — a word ending in -er or one of the irregulars like meer, minder, beter. Use als when the two things are said to be equal, in the patterns even ... als and (net) zo ... als.

1. Is one thing said to be more or less than the other? Then there is a comparative (groter, kleiner, meer, beter), and it takes dan: Deze tas is duurder dan die. (This bag is more expensive than that one.)
2. Are the two things said to be equal, using even or (net) zo? Then it takes als: Zij is even oud als haar broer. (She is as old as her brother.)
3. als also follows dezelfde/hetzelfde (the same) and anders takes dan: Ik heb dezelfde jas als jij (I have the same coat as you); Dat is anders dan ik dacht (That's different from what I thought).

• dan — for inequality, after any comparative: warmer dan, sneller dan, meer dan, beter dan.
• als — for equality, in even ... als and (net) zo ... als: even mooi als, net zo groot als.
• als — after dezelfde, hetzelfde, eenzelfde: hetzelfde boek als jij.

You will often hear groter als in speech, and many native speakers say it. In standard written Dutch — exams, letters, work — it is counted as an error: after a comparative the word is dan, so write groter dan, beter dan, meer dan. A memory hook: dan pairs with the -er ending; als pairs with even and zo.

One more detail: the careful standard is dan ik (with the subject pronoun), as in Hij is ouder dan ik. In everyday speech dan mij is common and widely accepted. For the fuller picture, including hoe ... hoe patterns, see dan or als in comparisons.