Carer quality of life is increasingly considered alongside patient quality of life in economic evaluation. Important questions remain about how to value carer and patient quality of life effects alongside one another. In this study, we estimated the relative social value of two conceptualisations of carer quality of life (health-related and care-related) compared to patient quality of life. Relative valuations were estimated using a person trade-off (PTO) study with 990 representative members of the UK public. Participants chose between hypothetical services that improved the quality of life of carers and patients, iterating to a point of indifference. Overall 84% of participants completing the task were willing to trade patient and carer quality of life effects. Relative to a reference point of 1 for patient health-related quality of life, we estimated a social value of 0.74 for carer health-related quality of life effects and 0.69 for carer care-related quality of life effects. In conclusion, public preferences appear to support the inclusion of carer quality of life effects within economic evaluation. The results provide a means to value different carer quality of life outcomes in economic evaluation, where such values are needed and deemed appropriate.