Norwood scale: the seven stages, and what each one really changes

A trichogram used to assess the progress of androgenetic alopecia on the Norwood Hamilton scale.

Summary

The Norwood scale is the shared language dermatologists and hair surgeons fall back on whenever they talk about male pattern baldness. Seven drawings, seven stages numbered 1 to 7, and nothing else. You can place yourself on it in half a minute in front of a mirror, and that is precisely why it has outlived every attempt to replace it.

A stage, though, is not a diagnosis, and it is nothing like a forecast. It describes a shape at one moment in time. It says nothing about how fast the loss will carry on, nor about what surgery could realistically give back. This page takes the seven stages one at a time, spends proper time on the type A variant that most articles dispose of in a single line, and explains what each situation means once an operation is genuinely being planned. If what you want first is to know which kind of loss you are dealing with, the overview of the forms of alopecia is a better place to start.

A descriptive tool, not a forecast

The scale describes the geometry of the loss: where the hair has gone, and along which pattern. It measures neither the cause nor the speed.

Labelled cross-section diagram titled Scalp structure, showing the epidermis, dermis and subcutaneous layer with the hair shaft, sebaceous gland, blood vessels, hair bulb and hair follicle

That distinction has consequences in the consulting room. Two men graded at the same stage 3 can be on opposite trajectories: one holds still for fifteen years, the other reaches stage 5 within four. What actually tells you about speed is the age at which the loss began, and the comparison between two photographs taken a year apart. Baldness that starts early, declared at twenty, is a far heavier signal than a stage 4 that turns up at fifty.

Nor does the scale say why you are losing hair. It was built for one mechanism and one only: androgenetic alopecia, meaning the gradual miniaturisation of the follicles, the small pockets in the skin that manufacture each hair, under the influence of a hormone derived from testosterone. That hormone, DHT, shortens the life cycle of any follicle genetically sensitive to it. The hair grows back finer and shorter with every turn, until it is no more than invisible down.

Diagram titled The hair cycle takes place in three phases, showing the anagen phase of hair growth lasting 2 to 5 years, the catagen phase when growth stops lasting 2 to 3 weeks, the telogen phase of hair loss lasting 2 to 4 months, then a new anagen phase

Round patches of loss, or a diffuse thinning spread evenly over the whole scalp, cannot be read on this scale at all. They belong to other classifications.

Where the scale came from

James Hamilton published the first systematic description of male balding patterns in 1951, and demonstrated the part androgens play in the process. His classification was useful but heavy going, with categories that overlapped.

In 1975 the dermatologist O’Tar Norwood revised it from a series of 1,000 patients. He brought the whole thing down to seven readable stages and added the type A variants, for the cases that had never fitted inside Hamilton’s framework. That is the version the world has used ever since. You will also see it called the Norwood-Hamilton scale, or the Hamilton-Norwood scale.

Gloved researcher in a laboratory holding a strand of hair with tweezers above a test tube, with DNA double helix motifs overlaid on the background

The seven stages, described so you can recognise them in a mirror

Take a light from above and a mirror in front of you. A phone held up as a second mirror is enough to see the vertex, meaning the crown at the top of the head.

Stage 1

No visible loss. The frontal hairline sits where it always has, in its adolescent position. This is the reference point, not a step in the balding process.

Stage 2

A slight retreat at the temporal points, the two triangular areas either side of the forehead, just above the temples. The recession is symmetrical and modest, of the order of one to two centimetres. Be careful with this one: the pattern very often corresponds to what is known as a mature hairline, the normal evolution of the male forehead somewhere between twenty and thirty. Plenty of men stop there permanently. A hollowing at the temples only signals baldness if it keeps moving.

Stage 3

The first stage dermatologists count as baldness in the clinical sense. The temporal points are clearly hollowed out and draw a definite M, sometimes a V. Scalp becomes visible in those areas under direct light. The loss is still frontal.

Stage 3 vertex

The same frontal recession as stage 3, but with thinning that begins at the crown. The two areas stay separated by a band of hair across the middle. This variant is common and difficult to spot on your own: thinning at the crown is nearly always discovered by somebody else, or on a photograph taken from behind.

Stage 4

The forehead has moved further back, and a properly bald zone has settled on the vertex. A band of hair, still reasonably dense, links the two sides of the head across the middle. That band is the marker of stage 4: as long as it holds its density, you are not at stage 5.

Stage 5

The same drawing, larger dimensions. The central band has thinned and now lets light through. The two bald zones are on the point of joining without having quite done so.

Stage 6

The band has gone. Forehead and vertex form a single bald surface. What is left draws a horseshoe around the sides and the back of the head. A few fine hairs may survive on top without covering anything at all.

Stage 7

The most advanced stage. All that remains is a narrow crown running from ear to ear, often sitting low on the nape, and those hairs are themselves finer than normal. This is the picture of complete baldness.

The type A variant, the one that changes the strategy

Norwood also described a parallel progression, written 2A to 5A, which concerns a small minority of men and is very easily missed.

In type A, the frontal hairline moves back evenly, from front to back, without the temporal points hollowing into an M and without a hole opening at the vertex. The forehead rises like a tide, keeping a more or less straight border. A man at 4A has therefore lost as much surface area as a classic stage 4, yet the top of his head is untouched.

Why does that matter in surgery? Because the strategy is not the same. On a classic stage 4, two distant zones have to be weighed against each other, the front and the vertex, with a limited stock of grafts. On a 4A, the whole surface to be covered is continuous: you draw a single frontal line and work backwards from it. The result is often more harmonious for the same number of grafts, because there is no intermediate zone to blend in. On the other hand, a type A that is still progressing will carry on receding, and a line drawn too low today becomes a trap ten years out. The design is therefore discussed at length with our surgical team before anyone operates.

What a stage means in grafts and in donor reserve

This is where the scale earns its place again. A surface to be covered translates into a number of grafts, a graft being one follicular unit taken from the back of the head, carrying anything from one to four hairs.

Before and after photographs of a patient with afro hair, the frontal line marked out on the left, restored density at the front on the right

Stages 1 and 2: nothing to operate on

The loss is not established, and working on a hairline that may still move back produces a visible mismatch a few years later.

Before and after photographs of a young patient, the planned frontal line drawn in on the left, a restored hairline on the right

Before and after photographs of a patient with glasses, a high thinning hairline on the left, a rebuilt frontal line on the right

Stages 3 and 4: the most comfortable window

At stage 3 and stage 3 vertex, the usual range is 1,500 to 3,000 grafts, depending on whether only the temporal points are treated or the crown as well. At stage 4 the order of magnitude moves to 3,000 to 4,000. The donor area is still intact and a single operation is generally enough.

Before and after photographs of a patient with curly hair, the frontal zone outlined on the left, dense curly hair at the front on the right

Before and after photographs of a patient with a marked frontal recession on the left and a rebuilt hairline framing the face on the right

Stages 5 to 7: choosing rather than covering

At stages 5 and 6, theoretical demand often runs past 4,500 grafts, and that is exactly where the reasoning flips over.

Before and after photographs of a patient with an advanced recession and the design line drawn on the left, a full frontal area on the right

Because the constraint is not the surface to be covered: it is the stock available. The donor area, that crown at the back and along the sides, holds a finite reserve that does not renew itself. It is genetically insensitive to DHT, which is why it holds firm while the rest goes, but you cannot harvest from it indefinitely without thinning it in turn. A stage 6 therefore demands a decision made openly: favour solid density across the front of the head, the part that shows in a mirror and in photographs, rather than a thin, even coverage spread over the whole surface. Our before and after results show that logic at work on the advanced stages.

At stage 7 the remaining crown is usually too poor to feed any credible coverage. A partial improvement is sometimes still possible. A restoration is not.

What the scale does not measure

Two blind spots, and both of them count.

The scale ignores hair quality altogether. It takes no account of density per square centimetre, nor of calibre, meaning the thickness of the shaft, nor of curl, nor of the contrast between hair colour and skin colour. Those parameters weigh enormously on the visual result. A man with thick, wavy hair graded at stage 4 can look less affected than a stage 3 with fine, straight hair. It is also why the beginning of hair loss goes unnoticed for so long: hair thins before it falls, and the scale does not see thinning.

Nor was it made for women. Female pattern loss takes a different shape, a diffuse thinning that widens the central parting while the frontal hairline holds, and it is graded on the Ludwig scale. Applying Norwood to a female patient simply makes no sense.

Its reliability has limits too. The studies that measured agreement between several dermatologists grading the same patients found only moderate concordance: the borders between neighbouring stages are blurred, and two practitioners will regularly hesitate between a 3 and a 4. More detailed classifications have been proposed to fix that, such as the BASP system, which combines the shape of the pattern with the density left behind. None has displaced Norwood in daily practice, because none is as quick to use.

Why a stage is never enough to decide on a transplant

A stage answers the question of where you stand. It does not answer what should be done.

Surgical team with Dr Cinik marking out the graft zones on a patient's shaved scalp before the operation

Three elements are missing, and they matter more. Age first, because before thirty the definitive pattern of the baldness is not yet written. Stabilisation next: is the loss still moving, or has it stopped? And the donor reserve, which has to be sufficient both for the surface aimed at today and for a possible second operation later on.

Surgeon drawing the future frontal line with a marker pen on a patient's scalp during consultation

Gloved hand examining the back of a patient's head, where the harvested donor area is visible

Operating on a baldness that is still active, with no medical stabilisation, means accepting that a bald zone will appear behind the transplanted hair. The implanted grafts themselves do not fall out again: they keep the resistance of the area they came from. But the native hairs around them go on falling if nothing holds them. The result then ages badly, not because of the transplant, but because everything else moved.

That is why a stage serves as the starting point of a consultation and not as its conclusion. Examining the scalp and going through the history of the loss does the rest. If you want to know where you stand before travelling anywhere, our page on whether you are suitable for a hair transplant sets out the criteria we check, and you can send us your photographs through the contact form for a first opinion. Our team performs hair transplant Turkey across every operable stage, and the first thing we look at is never the number, but what is left behind it.

Sources

Hamilton, J. B. (1951). Patterned loss of hair in man: types and incidence. Annals of the New York Academy of Sciences, 53(3), 708-728. https://doi.org/10.1111/j.1749-6632.1951.tb31971.x

Norwood, O. T. (1975). Male pattern baldness: classification and incidence. Southern Medical Journal, 68(11), 1359-1365. https://doi.org/10.1097/00007611-197511000-00009

Guarrera, M., Cardo, P., Arrigo, P., & Rebora, A. (2009). Reliability of Hamilton-Norwood classification. International Journal of Trichology, 1(2), 120-122. https://doi.org/10.4103/0974-7753.58554

Hong, H., Ji, J. H., Lee, Y., Kang, H., Choi, G. S., & Lee, W. S. (2013). Reliability of the pattern hair loss classifications: A comparison of the basic and specific and Norwood-Hamilton classifications. The Journal of Dermatology, 40(2), 102-106. https://doi.org/10.1111/1346-8138.12024