The Kirby-Desai scale: predicting sessions before the first pulse
How many sessions for laser tattoo removal? The Kirby-Desai scale scores skin type, location, colour, ink density, scarring and layering. With an online test.
“How many sessions will it take?” is the first question every client asks, and guessing at the answer is how specialists lose their trust three months later. There is a structured way to answer it.
The Kirby-Desai scale scores six factors, sums them, and the total gives you the predicted number of sessions. Its validation shows a correlation of R=0.757 against the real number of sessions performed — which makes it one of the more accurate clinical instruments available in this field.
The six factors
1. Fitzpatrick skin phototype
| Points | Phototype |
|---|---|
| 1 | I |
| 2 | II |
| 3 | III |
| 4 | IV |
| 5 | V |
| 6 | VI |
2. Location of the tattoo
| Points | Location |
|---|---|
| 1 | Head, neck, face |
| 2 | Upper trunk, shoulder |
| 3 | Lower trunk, thigh |
| 4 | Forearm, lower leg |
| 5 | Hand, wrist, ankle, foot |
3. Colour of the tattoo
| Points | Colour |
|---|---|
| 1 | Black only |
| 2 | Mostly black with some red |
| 3 | Mostly black and red, some other colours |
| 4 | Many colours |
4. Pigment density
| Points | Density |
|---|---|
| 1 | Amateur tattoo |
| 2 | Minimal |
| 3 | Moderate |
| 4 | Significant (dense professional work) |
5. Scarring in the tattooed area
| Points | Condition |
|---|---|
| 0 | No scarring |
| 1 | Minimal changes |
| 3 | Moderate scarring |
| 5 | Significant scarring |
6. Layering (cover-ups and retouching)
| Points | Situation |
|---|---|
| 0 | Primary tattoo, single layer |
| 2 | Cover-up or several layers |
Reading the total
| Total score | Predicted sessions |
|---|---|
| 4–5 | ~4–5 sessions (favourable) |
| 6–8 | ~6–8 sessions |
| 9–12 | ~9–12 sessions |
| 13–18 | ~13–18 sessions |
| 19–26+ | 20+ sessions (unfavourable) |
How many sessions will it take?
A quick estimate on the Kirby-Desai scale — for tattoos.
10 sessions, approximately
A rough estimate. More on the Kirby-Desai scale page.
A worked example
- Phototype II — 2 points
- Location: forearm — 4 points
- Colour: mostly black with some red — 2 points
- Density: moderate — 3 points
- Scarring: none — 0 points
- Cover-up: none — 0 points
Total: 11 points → approximately 11 sessions.
What the scale does not know
Use it honestly, which means knowing its blind spots:
- It does not account for your equipment — a compact device and a stationary system are not interchangeable
- It does not account for lifestyle: smoking, immune status
- It does not account for the ink’s actual composition, which is usually unknown
- R=0.757 is a good correlation, but more than 40% of the variability remains unexplained
So the working formula is: score + correction for your equipment + correction for lifestyle = the prognosis you give.
At the consultation
Score all six factors, add them up, and give the client a range — “probably 8 to 12 sessions” — then say plainly that this is a prognosis and not a guarantee. Where the score is high, 15 and above, tell them honestly that the course will be long, and consider whether a stationary laser is the better referral.
Clients do not lose trust because a course took ten sessions. They lose it because someone promised three.
You can run the test on the Kirby-Desai scale page.
Frequently asked questions
How many sessions do you need for laser tattoo removal?
The Kirby-Desai scale scores six factors: skin phototype, location, colour, pigment density, scarring and layering. The total predicts the number of sessions, from about 4–5 in favourable cases to 20+ in unfavourable ones.
How do you calculate the Kirby-Desai score?
Score all six factors and add them up. For example, phototype II (2), forearm (4), mostly black with some red (2), moderate density (3), no scarring (0) and no cover-up (0) give 11 points, approximately 11 sessions.
How accurate is the Kirby-Desai scale?
Its validation shows a correlation of R=0.757 with the real number of sessions, but more than 40% of the variability remains unexplained. It does not account for your equipment, lifestyle such as smoking and immune status, or the ink's actual composition.
What should I tell a client about the number of sessions?
Give a range, such as “probably 8 to 12 sessions”, and say plainly that this is a prognosis, not a guarantee. Where the score is 15 or above, tell them honestly that the course will be long.
