Despite long-held beliefs that “dark mode” extends battery life — particularly on phones equipped with power-saving OLED screens — a new BBC study has found that most users compensate by pushing their brightness levels higher, effectively negating any energy gains.
According to the research, 80 per cent of participants who switched their phones to a dark background then adjusted the brightness upwards, causing them to drain their batteries at a faster rate. By contrast, those opting for standard “light mode” were less likely to fiddle with screen settings, meaning the original lower brightness was maintained.
This dynamic runs counter to previous lab-based findings, including a 2021 Purdue University study showing phones set to dark mode use 42 per cent less power under full brightness conditions. Google engineers, likewise, had discovered a potential power reduction of up to 63 per cent for OLED displays in dark mode. However, those tests did not factor in real-world user behaviour.
Zak Datson, an engineer with the BBC’s Research & Development team, said that simple sustainability tips don’t always stand up to scrutiny in actual practice. “Some of the most common recommendations are overly simplistic,” he noted. “In the case of dark mode, some people end up using more energy.”
The BBC’s test underscores that the surest way to lengthen battery life is to reduce screen brightness. Lowering brightness significantly can halve energy consumption compared with a phone kept at maximum settings.
The study is part of the BBC’s broader sustainability campaign, as the corporation aims to slash its overall carbon emissions by 90 per cent by 2050. Among media-related carbon sources, the production of devices such as televisions and smartphones ranks as a major contributor, while in film production, travel is typically the largest emitter of carbon.
