Most Phone Chargers Use Almost No Power When Idle, Tests Show

Overview

• Independent consumer tests report modern phone, tablet and laptop external power supplies typically draw only fractions of a watt when not charging, producing only a few cents of electricity cost per year.
• Consumer labs and magazines found clear outliers among older or nonstandard adapters that draw multiple watts in standby, with measured examples of about 1.2 watts and 3.7 watts that raise annual costs to several euros.
• Accurate measurement of tiny standby currents requires sensitive, calibrated equipment because common plug-in watt‑meters can fail to register tenths of a watt and may have their own self‑consumption.
• Power use is substantially higher during active charging and can spike near full battery levels, for example an M1 MacBook Air charger measured about 6–8 W while running and up to 28 W at roughly 95% charge.
• EU Ecodesign limits for external power supplies have driven the low idle consumption of modern chargers, but unplugging or replacing rarely used, very old or visibly damaged chargers remains a simple step to reduce aggregate energy waste and lower fire risk, with one estimate of about 2.5 kWh per unused charger per year.