Holdaway Ratio: Incisor to Chin Balance Explained
The Holdaway ratio answers a simple question: is the lower incisor in balance with the chin? It compares two distances measured from the N-B line on the lateral cephalogram: the position of the lower incisor (L1-NB) and the prominence of the bony chin (Pog-NB). Ideally, they are equal. It is a small part of the Steiner analysis, but it is where the chin enters the treatment plan, through the third of Steiner’s chevrons. This article covers the definition, measurement, grading, the chevrons, clinical meaning and limits, and why the ratio should not be confused with Holdaway’s soft-tissue H-line.
What the Holdaway ratio measures
Two linear measurements, both in millimeters, both taken perpendicular to the N-B line:
- L1-NB (mm): the distance from the most labial point of the lower central incisor crown to N-B. Its Steiner norm is 4 mm ± 1.
- Pog-NB (mm): the distance from Pogonion, the most anterior point of the bony symphysis, to N-B. It expresses the prominence of the chin.
According to Holdaway, the lower incisor should sit as far in front of N-B as the chin does: L1-NB = Pog-NB, a 1:1 ratio. University course materials give Pog-NB no norm of its own for this reason: its reference is the incisor. They add a useful observation: Pog-NB is often large in hypodivergent patients and small, sometimes zero, in hyperdivergent ones.
Because both distances are read from N-B, the ratio describes the relationship between two mandibular structures, tooth and chin, rather than the position of the mandible in the face: it is a profile criterion. For the rest of the analysis, see our Steiner analysis guide.
Ratio or difference?
Despite its name, the ratio is read in practice as a difference in millimeters, L1-NB − Pog-NB. The grading taught in the university Steiner course handout:
| L1-NB − Pog-NB | Reading |
|---|---|
| 0 mm | Ideal balance (1:1) |
| 1 to 2 mm | Esthetics still satisfactory |
| 3 mm | Barely acceptable balance |
| 4 mm or more, in favor of the incisor | Uprighting the lower incisor becomes essential for the profile |
The sources do not all agree. Another course handout expresses the same idea as ratios: 1:1 ideal, 1:2 acceptable, 1:3 tolerable, 1:4 an indication for extraction. Boileau keeps only the strict rule (incisor and pogonion at the same distance from N-B), without any grading. Our free tools use the millimeter grading above.
There is also a practical argument for the difference. A true ratio cannot be calculated when Pog-NB is zero, which is precisely the small-chinned hyperdivergent case where the question matters most. The difference is always defined.
Our Steiner’s chevrons calculator also flags the opposite situation: when the incisor lies 3 mm or more behind the chin, it reports an incisor retruded relative to the chin.
How to measure it
- Use a calibrated cephalogram, taken in maximum intercuspation. Both values are distances, so they depend on the scale: courses give a magnification of about 7% with the source at 1.5 m. Without calibration, the numbers cannot be compared with any guideline.
- Place N and B carefully, then draw the N-B line and extend it below the chin.
- Choose the lower incisor: the most labially positioned central incisor, and its most labial crown point.
- Locate Pogonion, the most anterior point of the bony symphysis. The chin outline is sometimes faint, and a doubled lower border should be handled before you start.
- Measure both perpendicular distances, positive in front of N-B, negative behind it. A retrusive chin can give a Pog-NB of zero or less.
- Subtract and read the result against the grading.
One pitfall is specific to this measurement: an error on N or B tilts N-B and changes both values, and because Pogonion lies farther from Nasion than the incisor crown, the tilt moves Pog-NB more than L1-NB. Point B deserves particular care, as it is influenced by the position of the lower incisor.
Our free cephalometric analysis tool measures L1-NB in millimeters once the radiograph is calibrated and the lower labial landmark is placed, then passes ANB, U1-NA and L1-NB to the chevrons calculator. It does not place Pogonion: measure Pog-NB separately and type it in. The landmark definitions and their traps are covered in our cephalometric tracing guide.
The Holdaway ratio inside Steiner’s chevrons
Steiner summarized his planning in chevrons: a V pointing to the right, with ANB at the top, U1-NA and L1-NB (in millimeters) on the arms, and Pog-NB at the bottom. Chevron 1 holds the initial measurements. Chevron 2 is the compromise (function): the incisor positions Steiner considers acceptable for the estimated end-of-treatment ANB. Chevron 3 is where Holdaway comes in (esthetics). Chevron 4 reconciles the two.
Step 1: estimate chin growth
Chevron 3 uses the end-of-treatment chin, so growth must be estimated first: final Pog-NB = initial Pog-NB + growth. The guideline used by the calculator, from the course handouts: girls +1 mm over 2 years (about 0.5 mm per year), boys +2 mm (about 1 mm per year); more with an anterior rotation or if the initial Pog-NB is already large; 0 once growth is complete. The value is suggested, and you can change it.
Step 2: line the incisor up with the chin
According to Holdaway, the lower incisor should be in harmony with the chin: L1-NB = final Pog-NB. The upper incisor keeps the same relationship with the lower incisor as in chevron 2:
U1-NA = (U1-NA − L1-NB of chevron 2) + L1-NB
Step 3: average function and esthetics
Chevron 4, the solution, takes the average of each incisor position in chevrons 2 and 3, rounded to the nearest quarter millimeter. It sets the target L1-NB.
Step 4: convert the movement into space
Incisor repositioning (IR) = (final L1-NB − initial L1-NB) × 2, because both sides of the arch are involved. A negative value means the incisor moves back and uses up arch perimeter. It goes into the Steiner box together with crowding and the curve of Spee, as explained in our Steiner box guide (in French).
A worked example
These are the values of the "See an example" button in our calculator: ANB 6°, U1-NA 7 mm, L1-NB 8 mm, Pog-NB 1 mm, growing boy.
| Chevron | ANB | U1-NA (mm) | L1-NB (mm) | Pog-NB (mm) |
|---|---|---|---|---|
| 1, the problem | 6° | 7 | 8 | 1 |
| 2, the compromise | 4° (6 / 2 + 1) | 2 (6 − 4) | 4.5 (3.5 + 0.25 × 4) | 1 |
| 3, Holdaway | 4° | 0.5 ((2 − 4.5) + 3) | 3 | 3 (1 + 2) |
| 4, the solution | 4° | 1.25 | 3.75 | 3 |
The initial Holdaway difference is 8 − 1 = 7 mm: the incisor is far too forward for this chin. At the end, 3.75 − 3 = 0.75 mm, a satisfactory balance. IR = (3.75 − 8) × 2 = −8.5 mm of arch perimeter.
Now take the same measurements in a patient whose growth is complete. ANB does not change (6°), so chevron 2 gives U1-NA 0 mm and L1-NB 5 mm. The chin does not grow, so chevron 3 gives L1-NB 1 mm and U1-NA −4 mm. Chevron 4 gives U1-NA −2 mm and L1-NB 3 mm, and IR = (3 − 8) × 2 = −10 mm. Without the 2 mm of chin growth, the same patient needs 1.5 mm more arch length. The growth estimate is not a detail.
One boundary applies: Steiner’s compromise is only defined for a final ANB between −1° and 8°. Beyond that range, the calculator stops after chevron 1, because incisor compensation alone is no longer enough and correction of the skeletal discrepancy should be discussed. The Holdaway reading of the initial values remains displayed.
What the ratio tells you clinically
Incisor well ahead of the chin. This is the classic picture of a lower incisor proclined to compensate a Class II, or of a bimaxillary protrusion. A teaching case gives Pog-NB 1 mm against L1-NB 9 mm, described as a very unfavorable Holdaway balance. Courses point out that an incisor protrusion can create a need for space even without crowding, and one handout cites a 1:4 Holdaway ratio among the arguments for extraction. It is one argument among several, weighed with the space analysis, the profile, the vertical dimension and the periodontium.
Prominent chin, hypodivergent face. A large Pog-NB allows the incisor to stay further forward. This converges with other guidelines from the courses: in hypodivergent patients, Boileau advises accepting a slightly more labial lower incisor, and Tweed’s rule tolerates an IMPA up to about 92° when the FMA is below 22°.
Small chin, hyperdivergent face. Holdaway asks for an upright incisor, and so does Tweed, whose target is more demanding above an FMA of 28° (FMIA 65°). Both push toward retraction, which is exactly where the profile must be watched.
Steiner and Tweed do not always agree. Boileau compares them on a 13-year-old boy (ANB 7°, Wits 8.5 mm, FMA 25°, FMIA 51°): the Steiner target, weighted by Holdaway, is U1-NA 1 mm and L1-NB 3.5 mm, while Tweed’s target FMIA of 68°, applied in full, would cost about 13.6 mm of arch length. Steiner compensates mainly the sagittal discrepancy; Tweed bases the lower incisor target on the divergence. The practitioner decides between them.
The limits of the Holdaway ratio
- Periosteal landmarks and an estimated chin. Pogonion and point B remodel, B depends on the incisor, and the growth guideline is only an average.
- Bone is not skin. The ratio uses the bony chin. Holdaway himself observed that a thick soft-tissue covering of the chin can balance a profile with the lower incisors further forward than usual (Holdaway, 1984, Am J Orthod, PubMed).
- Lips do not follow one to one. The course guideline is about 1 mm of upper lip change for 2 mm of incisor retraction, and 1 mm of lower lip change for 1.75 mm. Boileau warns that excessive retraction flattens the profile when the target ignores nose and chin growth; Bassigny preferred slight incisor crowding to a flattened profile.
- Era and population. The chevrons were designed for a given time and population, and their values differ between reproductions. Refer to the version used in your program.
- Thin evidence. A PubMed search found little research testing the bony L1-NB to Pog-NB ratio itself; most "Holdaway" studies deal with his soft-tissue analysis. The ratio is a teaching guideline, not an evidence-based threshold.
Holdaway ratio vs H-line and H angle
The same author is behind a second, different tool. Holdaway published a soft-tissue cephalometric analysis in two parts (Holdaway, 1983, Am J Orthod, PubMed; Holdaway, 1984, Am J Orthod, PubMed). Its main reference is the H line, usually drawn tangent to the soft-tissue chin and the upper lip, and the H angle, which describes its inclination relative to the facial profile.
Holdaway argues that a hard-tissue analysis alone is inadequate for planning, and that the lips and chin should line up near the H line. The H angle, he writes, must increase with skeletal convexity, and the more convex the skeleton, the farther forward the lower incisors must be left. He also warns against "dishing" well-balanced faces with only 5 or 6 mm of lower arch length discrepancy. These norms vary between populations: in 62 Persian adults with normal occlusion, the H angle, skeletal convexity, upper lip thickness and soft-tissue chin thickness were larger than Holdaway’s norms (Taki et al., 2009, Angle Orthod, PubMed).
| Holdaway ratio | H line and H angle | |
|---|---|---|
| Tissue | Bone and tooth | Soft tissue |
| Measurement | L1-NB vs Pog-NB, in mm | Lips and nose relative to a line through the soft-tissue chin and upper lip |
| Part of | Steiner analysis, chevron 3 | Holdaway’s own soft-tissue analysis |
| Use | Target position of the lower incisor | Assessment and planning of the soft-tissue profile |
The university courses behind this article do not teach the H line. For soft tissue, they use Steiner’s S line and Merrifield’s Z line and Z angle.
In practice: a checklist
- Calibrate the radiograph before measuring L1-NB or Pog-NB.
- Check N and B before trusting the N-B line, then extend it below the chin.
- Read L1-NB − Pog-NB in millimeters against the 1-2 / 3 / 4 mm grading, and state which convention you use.
- Estimate chin growth from age, sex and rotation, and set it to 0 once growth is complete.
- Build chevrons 2, 3 and 4 and convert the result into incisor repositioning for the Steiner box.
- Compare with Tweed’s target and with the clinical profile (lips, nose, soft-tissue chin) before deciding.
Frequently asked questions
What is a normal Holdaway ratio?
The ideal is 1:1: the lower incisor (L1-NB) lies as far in front of the N-B line as the chin (Pog-NB). A difference of 1 to 2 mm remains esthetically satisfactory, 3 mm is barely acceptable, and from 4 mm in favor of the incisor, uprighting it becomes essential for the profile. Some course materials express the same scale as ratios (1:2, 1:3, 1:4).
Is the Holdaway ratio the same as the H-line?
No. The Holdaway ratio compares the lower incisor with the bony chin, from the N-B line, and is used in Steiner’s chevrons. The H line belongs to Holdaway’s soft-tissue analysis: it relates the lips and the nose to a line drawn through the soft-tissue chin and upper lip.
Does a large Holdaway difference mean extraction?
Not by itself. It indicates that the lower incisor is too far forward for the chin, which creates a need for space. Whether that space comes from extractions depends on the whole space analysis, the profile, the vertical pattern and the periodontium. The decision stays with the practitioner.
Can I calculate the Holdaway ratio online?
Yes. Enter ANB, U1-NA, L1-NB and Pog-NB in our free Steiner’s chevrons calculator: it shows the initial and resulting Holdaway difference with its reading, builds the four chevrons and calculates the incisor repositioning. Our cephalometric analysis tool measures L1-NB from the radiograph; Pog-NB is entered by hand.
With GS Ortho
In GS Ortho, AI places 29 landmarks on the lateral cephalogram, soft-tissue profile included, and the Steiner analysis is calculated straight away, alongside Tweed. You check each landmark, correct it if needed, then validate: the decision stays yours. The measurements feed into the diagnostic studio, the Steiner box carries the incisor repositioning into the patient’s space analysis, and an orthodontist’s opinion can be requested in one click, straight from the case. The GS Ortho interface is currently available in French.