*End Stage AIDS, Hospitalized, High Viral Load**Suspected HIV, IV drug user, Unknown needle with high local HIV prevalence Total Risk = Basic Risk x Volume of Inoculum ModifierBasic Risk = 1 / (Source Modifier * Inoculum Type Modifier * Method of Transmission Modifier) The author also cites some every day life risks to help provide risk perspective:

Risk of dying in the next 12 months
Overall risk of dying in the next 12 months (all causes)	1/3 000
Specific causes of death in the next 12 months
from a lightning strike	1/2 000 000
in an accident in your bathtub or shower	1/1 000 000
from a previously unknown allergy to a prescribed drug	1/1 000 000
by choking to death on food	1/160 000
in a bicycle accident (if you own a bicycle)	1/130 000
from toxic shock if you use tampons	1/100 000
by drowning	1/50 000
from a fire	1/50 000
as a pedestrian hit by a car or truck	1/40 000
in a work-related accident (office workers)	1/37 000
from a fall	1/20 000
in a work-related accident (overall)	1/11 000
by being murdered	1/11 000
while jogging (average 2 h/wk)	1/10 000
in a road accident	1/6 000
from any kind of accident	1/3 000
Other risks
risk of dying on your next commercial jet flight	1/5 000 000
lifetime risk of being on a bridge when it collapses	1/4 000 000
risk of dying if you get influenza	1/5 000
risk of being diagnosed with cancer in the next 12 months (overall death rate 50%)	1/3 600
risk of being diagnosed with lung cancer in the next 12 months if you are (or were) a smoker (overall death rate about 90%)	1/250
risk of having a heart attack in the next 12 months if you are over 35 years of age	1/77

Vertesi L. Risk Assessment Stratification Protocol (RASP) to help patients decide on the use of postexposure prophylaxis for HIV exposure. CJEM. 2003 Jan;5(1):46-8. PubMed PMID: 17659153.