A tattoo black tattoo on the upper arm reached 75% fading after 4 sessions at Docteur Tattoo over 2 years and 6 months. Total cost: $1,120.

Before (session 0) and after (session 4) at Docteur Tattoo.
The tattoo
A medium black tattoo on the upper arm, 1–5 yrs old when treatment began.
The upper arm is close to the axillary lymph nodes, which supports efficient clearance between sessions.
Timeline
4 sessions over 2 years, 6 months.
Sessions were spaced 6+ months apart.
Cost
Docteur Tattoo: $1,120 across 4 sessions works out to $280 per session.
Reputable providers typically charge $350 to $700 per session; $280 falls within that range.
The laser
Docteur Tattoo treated this case with the PicoSure, a picosecond platform.
For black ink, it operates at 1064 nm with a pulse duration of 550 - 750 ps.
PicoSure's black ink adapter (1064nm) is considered largely ineffective by most experienced providers; the native 755nm is its strength.
Bottom line
The last 5 to 10 percent of clearance is consistently the hardest phase: residual ink sits deepest, immune response slows, and the composition of what remains is unknown.