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Introduction Calcinosis is a common complication of systemic sclerosis (SSc) associated with substantial morbidity. The aetiology of calcinosis is unknown with no effective treatments. We sought to determine the frequency, characteristics and associations of calcinosis in a large SSc cohort.Material and Methods Patients from the Australian Scleroderma Cohort Study were included. Calcinosis was identified by treating physicians. We compared demographic and disease characteristics of those who had calcinosis with those who did not. Associations of calcinosis with physical function measured using Scleroderma Health Assessment Questionnaire (SHAQ), health-related quality of life (HRQoL) measured using 36-Item Short Form Survey (SF-36) and Patient-Reported Outcome Measurement Information System (PROMIS), and employment status were determined using univariable methods.Results Of 1981 patients, 875 (44.2%) ever had calcinosis (42.3% of 1442 limited SSc patients, and 50.4% of 504 with diffuse SSc). Calcinosis patients had longer disease duration (9.1 vs 5.9 years, p<0.001). Centromere ANA (48.4%) was the most common antibody in calcinosis patients, followed by RNAP3 (16.4%) and Scl-70 (13.7%). Patients with calcinosis were more likely to have RNAP3 (16.4% vs 12.6%, p0.046) and less likely to have RNP antibodies (4.1% vs 8.7%, p<0.001) compared to patients without calcinosis. Calcinosis was associated with vascular manifestations of telangiectasia, abnormal nail fold capillaroscopy, digital ulcers and gangrene compared with those who never had calcinosis (p<0.001). Gastro-oesophageal reflux disease, oesophageal strictures, gastric antral vascular ectasia and gastrointestinal dysmotility were more common with calcinosis (p=0.001). Calcinosis was also associated with pulmonary arterial hypertension (p0.003), interstitial lung disease (p0.023) and SSc myocardial disease (p0.005); but not SRC or myositis. Calcinosis patients were more likely to have joint contractures, synovitis and higher ever recorded mRSS (p<0.001).There was no significant difference in sex, race or smoking status in those with or without calcinosis. Those with calcinosis had significantly worse physical function (highest SHAQ mean 3.8 vs 2.8, p<0.001), lower SF36 mental (38.8 vs 41.8, p< 0.001) and physical (30.7 vs 34.8, p<0.001) component scores. PROMIS pain interference scores were higher with calcinosis (12.0 vs 9.0, p<0.001). Unemployment (15.4% vs 11.8%) and disability preventing work (11.4% vs 5.4% p0.001) were more common in those with calcinosis.Conclusions Calcinosis is a common manifestation of SSc, associated with vascular, GIT and cardiopulmonary SSc manifestations. Calcinosis is significantly associated with poorer physical function, poorer HRQoL, more pain interference, and reduced employment. This study highlights the substantial unmet need for effective therapeutics in SSc calcinosis.