What is the Douma adaptation?

W. H. Douma adjusted the original English Flesch Reading Ease coefficients in 1960 to fit Dutch. The formula becomes 206.84 minus 0.77 times syllables per 100 words minus 0.93 times average sentence length, keeping the same 0 to 100 scale.

What is a good Dutch Flesch score?

Scores of 60 to 70 are fairly easy and readable by most adults. Above 70 is easy and conversational. Below 50 is standard to difficult and suited to professional or academic readers. Aim for 60 or higher for general web copy.

How are Dutch syllables counted?

Each word is scanned for vowel groups, with common Dutch digraphs and diphthongs like aa, ij, ei, ui, ou, and ie treated as a single vowel sound. This vowel-nucleus method closely approximates spoken syllable counts in Dutch.

Why does Dutch use a different formula than English?

Dutch words and syllable patterns differ from English averages, so the original constants would mis-score Dutch text. Douma recalibrated the base constant and term weights so a score of 60 means the same difficulty band it does in English.

Is my text sent anywhere?

No. All counting and scoring happens locally in your browser. Nothing is uploaded, stored, or logged, so it is safe to paste private Dutch drafts.

Dutch Flesch Readability

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The Douma readability formula is a Dutch-language adaptation of the well-known Flesch Reading Ease test. Because Dutch syllable and word lengths differ from English, applying the original Flesch constants would give misleading results, so W. H. Douma recalibrated the formula in 1960 for Dutch prose.

How it works

The score uses three counts: total words, total sentences, and total syllables. From these it derives average sentence length and syllables per 100 words. The Douma formula is:

RE = 206.84 − 0.77 × (syllables per 100 words) − 0.93 × (words per sentence)

Since syllables per 100 words equals 100 times the syllables-per-word ratio, the syllable term is equivalent to 77 times syllables per word. Higher scores mean easier text on the same 0 to 100 scale used by English Flesch. Syllables are estimated by counting vowel groups while treating Dutch digraphs such as “ij”, “ei”, and “ou” as one vowel sound.

Tips and example

A short Dutch sentence like “De kat zit op de mat” uses single-syllable words and scores near the top of the scale. A formal sentence packed with long compounds like “leesbaarheidsonderzoek” and several subordinate clauses pushes the score down sharply. To make Dutch text easier, cut sentence length first, since average sentence length carries strong weight, then prefer shorter words and unpack long compound nouns. For public-facing Dutch copy, target a Reading Ease of 60 or higher.