Coverage is an important dimension in measuring the effectiveness of needle and syringe programmes in providing sterile injecting equipment for people who inject drugs. The World Health Organization (WHO), the United Nations Office on Drugs and Crime (UNODC) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) currently recommend methods for measuring coverage at the population level, that is, across an estimated population of people who inject drugs within a given geographical area. However, population-level measures of coverage rely on highly uncertain population estimates and cannot capture the different levels of syringe acquisition and injecting episodes among individual users. Consequently, such measures only broadly evaluate the extent of programme service delivery, rather than describe how people who inject drugs as individuals and sub-groups interact with needle and syringe programmes. In response to these limitations, several researchers have proposed measuring coverage at the individual level, by the percentage of injecting episodes in relation to the number of sterile needles and syringes acquired. These measures evaluate coverage according to each individual's needs. Such measures provide enhanced information for planning and monitoring of harm reduction programmes and have now been used in multiple international research studies. We advise that WHO, UNODC and UNAIDS add individual-level coverage measurement methods to their international monitoring guidelines for harm reduction programmes. By doing this, more responsive and effective programmes can be created to better reduce injecting risk behaviours and blood-borne virus transmission among people who inject drugs.