Rules of Nun Sukun and Tanwin: A Complete Guide to Izhar, Idgham, Iqlab, Ikhfa
Backed by a network of 5,000+ Quran and Arabic teachers, graduates of selective campuses, trained in the Arabi Method.
The rules of nun sukun and tanwin are tajweed guidelines that govern how a silent nun or a tanwin is read when it meets the following Arabic letter. There are four rulings: izhar (clear), idgham (merging), iqlab (changing into mim), and ikhfa (concealed), each with its own letters.
What are the rules of nun sukun and tanwin?
The rules of nun sukun and tanwin are a set of tajweed guidelines that determine how a silent nun (a nun carrying a sukun, written نْ) or a tanwin is pronounced when followed by one of the twenty nine Arabic letters. The nun sukun is permanent, present in the text and pronounced both in washal (continuing) and waqf (stopping). Tanwin is an additional silent nun appearing at the end of a word as a doubled vowel sign: fathatain (ـً), kasratain (ـٍ), or dhammatain (ـٌ), heard when continuing and dropped when stopping.
Scholars of tajweed group nun sukun and tanwin in one chapter because both are essentially the sound of a silent nun. This nun sound, produced from the tip of the tongue, interacts with the letter that follows it. From that interaction arise the four rulings you study, namely izhar, idgham, iqlab, and ikhfa. Mastering the rules of nun sukun and tanwin is the foundation of reciting the Quran with tartil as commanded.
Understanding this chapter opens the door to precision in recitation. A single silent nun read incorrectly can change how a verse sounds and at times blur its meaning. With the Arabi method, you first learn to recognise the letters of each ruling, then train your tongue and ear until correct recitation becomes a firmly settled habit.
وَرَتِّلِ الْقُرْآنَ تَرْتِيلًا
wa rattilil-qur'aana tartiilaa
And recite the Quran with measured recitation (slowly and correctly).
Telling nun sukun and tanwin apart
Nun sukun is the letter nun carrying a sukun, present visibly in the rasm (script) of the Quran with a small circle above it (نْ). It can sit in the middle of a word as in أَنْعَمْتَ, or at the end as in مِنْ. Because it is an original letter, nun sukun is pronounced in every situation, whether you connect to the next word or stop upon it.
Tanwin literally means giving a nun sound. It is an extra silent nun at the end of a noun that is heard in pronunciation yet is not written as the letter nun. Its symbol is a doubled vowel sign: fathatain on عَلِيمًا, kasratain on عَلِيمٍ, and dhammatain on عَلِيمٌ. Tanwin sounds only during washal; when you stop on a word with tanwin, its nun sound drops and is replaced according to the rules of stopping.
This distinction matters in practice. The rules of nun sukun and tanwin apply during washal, that is, when the silent nun genuinely meets the following letter. When you stop on a tanwin, the rulings of izhar, idgham, iqlab, and ikhfa no longer apply because the tanwin has already changed under the rules of waqf. This is why tajweed teaching always begins by distinguishing these two forms of silent nun before moving to the four rulings.
First ruling: Izhar Halqi (clear pronunciation)
Izhar linguistically means clear or evident. In tajweed terminology, izhar halqi is reading the nun sukun or tanwin clearly, without a sustained nasal hum (ghunnah), when it meets one of the throat letters (huruf halqi). There are six such letters: hamzah (ء), ha (هـ), 'ain (ع), ha (ح), ghain (غ), and kha (خ). They are called halqi because all six emerge from the throat, so the nun sound is uttered distinctly before moving on to that throat letter.
To read it, pronounce the silent nun firmly from the tip of the tongue, then connect directly to the throat letter without adding a hum and without an excessive pause. The nun sound must come out whole and clean. Examples include nun sukun meeting 'ain in أَنْعَمْتَ (QS Al-Fatihah: 7), nun sukun meeting hamzah in مِنْ آمَنَ, and tanwin meeting ha in جُرُفٍ هَارٍ (QS At-Taubah: 109). In all these cases the nun is read clearly.
A frequent error is adding a hum to izhar or holding the nun sound too long so that it resembles ikhfa. Correct practice makes you sensitive to when the nun should be clear and when it should be concealed. Izhar halqi is the easiest ruling to recognise because its six letters all gather in the throat, and this is usually taught first in the order of the four rules of nun sukun and tanwin.
Second ruling: Idgham (merging)
Idgham means to insert or to merge. In this chapter, idgham is merging the sound of the nun sukun or tanwin into the following letter so that the two become a single doubled letter. It has six letters, gathered in the word يَرْمَلُونَ, namely ya (ي), ra (ر), mim (م), lam (ل), wau (و), and nun (ن). Idgham only applies when the idgham letter is in a word separate from the silent nun; if it is in the same word, the ruling becomes absolute izhar.
Idgham is of two kinds. First, idgham with ghunnah (idgham bighunnah) on four letters gathered in the word يَنْمُو, namely ya, nun, mim, and wau. Here the nun is merged while holding a hum for about two counts. For instance مَنْ يَقُولُ is read mayyaquulu with a hum, and a tanwin example with ghunnah, خَيْرٌ وَأَبْقَى, is read khairuw wa abqaa.
Second, idgham without ghunnah (idgham bilaghunnah) on two letters, namely lam (ل) and ra (ر). Here the nun is merged completely into the lam or ra leaving no hum. For example مِنْ لَدُنْهُ is read milladunhu, and مِنْ رَبِّهِمْ is read mirrabbihim. Distinguishing idgham with ghunnah from idgham without ghunnah is the heart of mastering this second ruling, since one kind holds a hum and the other has none.
Third ruling: Iqlab (changing)
Iqlab linguistically means to flip or to change. In tajweed, iqlab is changing the sound of the nun sukun or tanwin into the sound of mim (م) when it meets a single letter, namely ba (ب), accompanied by a hum held for about two counts. There is only one letter of iqlab in this entire chapter, which makes iqlab the ruling with the fewest letters yet easy to recognise. In the mushaf, iqlab is often marked with a small mim above the nun or tanwin.
To read it, when the silent nun or tanwin meets ba, you do not pronounce the nun sound; you replace it with a mim sound concealed toward the ba while holding a hum. The two lips are brought together lightly to prepare for the mim. Examples include nun sukun meeting ba in أَنْبِئْهُمْ, read ambi'hum, and مِنْ بَعْدِ, read mim ba'di with a hum. A tanwin example is سَمِيعٌ بَصِيرٌ, read samii'um bashiir.
The wisdom of iqlab is the closeness of the points of articulation. Mim and ba both emerge from the two lips, so it is lighter for the tongue to change nun into mim than to force a nun sound directly into ba. A common error is reading the nun clearly without changing it into mim, or forgetting to hold the hum. Practise by bringing the lips together gently so the mim forms fully while the hum is preserved.
Fourth ruling: Ikhfa Haqiqi (concealed pronunciation)
Ikhfa linguistically means to conceal or to hide. Ikhfa haqiqi is reading the nun sukun or tanwin with a sound concealed between izhar and idgham, accompanied by a hum held for about two counts, when it meets one of the fifteen letters of ikhfa. It is called haqiqi (true) because the concealment of the nun genuinely takes place; the nun sound is neither fully clarified nor fully merged.
The fifteen letters of ikhfa are the remaining Arabic letters after removing the letters of izhar, idgham, and iqlab, namely ta (ت), tha (ث), jim (ج), dal (د), dhal (ذ), za (ز), sin (س), shin (ش), shad (ص), dhad (ض), tha (ط), zha (ظ), fa (ف), qaf (ق), and kaf (ك). Scholars arranged them in verse so they are easy to memorise. Because they are the most numerous, ikhfa is the ruling you encounter most often when reciting the Quran.
To read it, place the tongue at the point of articulation of the nun, then conceal its sound while holding a hum, with the mouth already preparing for the following ikhfa letter. The quality of the hum follows the letter after it, heavier near the elevated letters such as qaf and tha, lighter near the others. Examples include nun sukun meeting ta in كُنْتُمْ, read kun-tum concealed, tanwin meeting jim in خَلْقٍ جَدِيدٍ, and nun sukun meeting qaf in مِنْ قَبْلُ. This balanced concealment is the mark of correct ikhfa.
Quick table and how to memorise the four rulings
To make them easy to remember, you can summarise the rules of nun sukun and tanwin in four groups. First, izhar halqi with six throat letters (ء هـ ع ح غ خ) read clearly without a hum. Second, idgham with six letters (ي ر م ل و ن) read merged, split into with ghunnah on ي ن م و and without ghunnah on ل ر. Third, iqlab with one letter (ب) changed into mim with a hum. Fourth, ikhfa with the remaining fifteen letters read concealed with a hum.
A quick way to confirm the ruling is to look at the letter after the silent nun. If it is one of the six throat letters, it is izhar. If it is within يرملون, it is idgham. If it is the letter ba, it is iqlab. Other than these three, it is certainly ikhfa. This elimination method lets you determine the ruling quickly, because ikhfa is the final fallback for the fifteen letters that do not fall under the other three rulings.
Many teachers use memory keys. For idgham with ghunnah, the word يَنْمُو. For idgham without ghunnah, the two letters lam and ra. For ikhfa, the well known verse that gathers its fifteen letters. With the Arabi method, memorising these letter groups is paired with reading directly from the mushaf, so that theoretical knowledge soon turns into a recitation skill you command with confidence.
Understanding ghunnah and the length of the hum
Ghunnah is the nasal hum produced from the nasal cavity (khaishum) and is an inherent quality of the letters nun and mim. In the rules of nun sukun and tanwin, ghunnah appears in three rulings, namely idgham with ghunnah, iqlab, and ikhfa haqiqi. In izhar halqi and idgham without ghunnah, there is no sustained hum because the nun is read clearly or merged completely with no remainder.
The commonly taught length of the hum is about two counts, that is, the duration of two beats of a moderate finger movement. A hum that is too short makes the recitation hurried and loses the mark of its ruling, while a hum that is too long makes the recitation feel exaggerated. Practising under the guidance of a qualified teacher helps you measure the hum consistently.
The quality of the hum is also influenced by the following letter. In ikhfa, the heaviness or lightness of the hum follows the quality of the letter, heavier near elevated letters such as tha, qaf, shad, and dhad, lighter near the lowered letters. This sensitivity to the nuance of the hum is what separates a beginner's recitation from a recitation that is precise and pleasant to hear.
Common mistakes in reading nun sukun and tanwin
The first mistake is adding a hum to izhar halqi. Some readers hold the nun sound when meeting a throat letter so that it resembles ikhfa, whereas izhar requires a clear and clean nun with no sustained hum. Practise by pronouncing the nun firmly then connecting directly to the throat letter.
The second mistake is swapping idgham with ghunnah and without ghunnah. Some read lam and ra with a hum, though both are without ghunnah. Conversely, some merge ya, nun, mim, and wau with no hum, though all four carry ghunnah. The third mistake is reading iqlab with a clear nun sound while leaving it unchanged into mim, or pressing the lips too hard so the mim becomes excessive.
The fourth mistake, in ikhfa, is that some readers clarify the nun too much so it approaches izhar, or merge it too much so it approaches idgham. Ikhfa requires a middle, concealed position with a hum. The fifth mistake is applying the ruling while stopping on a tanwin, whereas the rules of nun sukun and tanwin apply only during washal. Recognising these patterns of error in advance speeds up the improvement of your recitation.
Glossary of key terms
Nun sukun: the letter nun carrying a sukun or silent, written نْ, pronounced in both washal and waqf. Tanwin: an additional silent nun at the end of a word as a doubled vowel sign (ـً ـٍ ـٌ), pronounced during washal and dropped during waqf. Izhar: reading clearly without a sustained hum. Idgham: merging the nun into the following letter to form a single doubled letter.
Iqlab: changing the nun or tanwin into a mim sound with a hum when it meets ba. Ikhfa: reading with a concealment between izhar and idgham accompanied by a hum. Ghunnah: the nasal hum from the nasal cavity, an inherent quality of nun and mim. Bighunnah: with ghunnah. Bilaghunnah: without ghunnah.
Halqi: relating to the throat, the point of articulation of the six izhar letters. Haqiqi: true, the name for ikhfa because the concealment of the nun genuinely takes place. Harakat: a unit of timing in tajweed, one count equal to one moderate finger movement. Washal: connecting recitation. Waqf: stopping. Makhraj: the point of articulation of a letter. Isti'la: the quality of letters whose tongue rises, producing a heavy sound.
Step by step
-
Recognise the form of the silent nun in the text
Notice whether you are facing a nun sukun (نْ) or a tanwin (the doubled signs ـً ـٍ ـٌ). Make sure the ruling is applied during washal, when the silent nun meets the following letter.
Mark nun sukun and tanwin in your practice mushaf with a pencil so your eye learns to spot them quickly.
-
Look at the following letter and determine the ruling
Compare the letter after the silent nun with the four groups. Six throat letters mean izhar, the letters يرملون mean idgham, the letter ba means iqlab, and the remaining fifteen letters mean ikhfa.
Use the elimination method: if it is outside izhar, idgham, and iqlab, it is certainly ikhfa.
-
Apply the pronunciation matching the ruling
For izhar, read the nun clearly with no hum. For idgham, merge into the following letter, with a hum on ينمو and with no hum on lam and ra. For iqlab, change the nun into a mim with a hum. For ikhfa, read concealed with a hum.
Hold the hum on idgham with ghunnah, iqlab, and ikhfa for about two counts, balanced and steady.
-
Practise with Quranic examples and seek correction
Read short chapters such as those in the thirtieth part of the Quran, recognise each rule of nun sukun and tanwin within them, then repeat until fluent. Ask for correction from a qualified teacher.
Record your recitation then listen back to check the clarity of izhar and the accuracy of the hum.
-
Measure the length of the hum and review continuously
Check whether the hum on idgham with ghunnah, iqlab, and ikhfa is truly about two counts, using a finger movement as your gauge. Compare your recitation with that of a teacher or a trusted reciter, note where the hum falls short or runs long, then seek correction regularly until the length is consistent and settled.
Set a weekly improvement target, for instance focusing this week on steadying the ikhfa hum, so your review stays focused and measurable.
Frequently Asked Questions
How many rules of nun sukun and tanwin are there?
What is the difference between nun sukun and tanwin?
What are the letters of izhar halqi?
How do you read iqlab?
Why does ikhfa have the most letters?
What is the difference between idgham with and without ghunnah?
Do these rulings apply when stopping on a tanwin?
Sources and references
- Hidayat al-Mustafid fi Ahkam at-Tajwid — Muhammad al-Mahmud
- Tuhfat al-Athfal wal Ghilman fi Tajwid al-Quran — Sulaiman al-Jamzuri
- At-Tibyan fi Adab Hamalat al-Quran — Imam an-Nawawi
- Ghayat al-Murid fi Ilm at-Tajwid — Atiyyah Qabil Nashr
Other Arabi Guides
Quran Recitation What Is the Ideal Age for a Child to Start Learning to Recite the Quran?
The ideal age to start learning to recite the Quran is around 4 to 6 years, through a joyful introduction to the hijaiyah letters. Read Arabi's age-by-age guide for every age.
Read article
Teachers How to Choose the Right Quran Teacher for Your Family
A guide to choosing the right Quran teacher: the teacher's expertise and educational background, patience in teaching, fit with the student, and a clear method. For all ages.
Read article
Tahfidz A Memorisation Method That Lasts: How Quran Hifz Stays Firm
A guide to a Quran memorisation method that lasts: talqin, staged review, and muroja'ah with the sabaq, sabqi, manzil system. How hifz stays firm, for all ages.
Read articleReady to Begin Learning with Arabi?
Expert teachers are ready to guide you, one on one, online or in person. Free consultation, no commitment.