Expansion and contraction vs. low and high grammatical density
Depending on the target language, a translated document invariably comes out longer or shorter than the original source copy. This phenomenon in translation is referred to as expansion and contraction. Languages have different expansion and contraction factors, so when English is translated into German, the text will expand by 15% to 35%. By comparison, translating English into French will result in a 15% to 20% expansion and English to Swedish in a -10% to -15% contraction (-25% to -40% for Finnish).
To put it simply, some languages use more words than others to express the same ideas. French researchers at Université de Lyon determined that these languages have a lower grammatical density, defined as the amount of information conveyed per syllable. What’s interesting is that expansion and contraction as well as high and low grammatical density also correlate to the speed with which languages are spoken.
The same researchers observed that the faster and slower languages conveyed information at the same rate. They conjectured that despite the great diversity of languages in the world, they all deliver a constant rate of information, which may be possibly tuned to the human perceptual system. So, our ears are not deceiving us: some languages sprint and others stroll but we tend to tell each other the same stories in the same span of time.
Approximate expansion and contraction for:
English to French +15% to +20%
English to German/Dutch +30% to %40
English to Spanish +20% to +30%
English to Italian +10% to 25%
English to Portuguese +15% to +30%
English to Swedish/Danish -10% to -15%
English to Norwegian -5% to -10%
English to Finnish -20% to -40%
English to Polish +20% to +30%
English to Czech/Russian +15%
English to Greek` +10%