Appliance Cost Lab

Laptop guide

How much electricity does a laptop use?

Workload, charging state, display brightness, battery management, sleep mode, docks, and accessories all affect wall-input energy.

A charger’s printed maximum output is a capability limit, not proof of the laptop’s active wall draw. Measure the complete setup in the operating modes you use.

Three reproducible scenarios

Three published laptop electricity-cost scenarios
Scenario Visible inputs Annual energy Annual cost
30 W for four weekday hours 30 W; 4 h/day; 5 days/week; 100% duty; 1 W idle for 21.143 h/day; $0.18/kWh 39.003 kWh $7.02
60 W for six weekday hours 60 W; 6 h/day; 5 days/week; 100% duty; 2 W idle for 19.714 h/day; $0.18/kWh 108.249 kWh $19.48
90 W for eight weekday hours 90 W; 8 h/day; 5 days/week; 100% duty; 3 W idle for 18.286 h/day; $0.18/kWh 207.737 kWh $37.39

$0.18/kWh is an illustrative comparison rate, not a national or current market price. These wattages are editable inputs, not product-class claims.

How to calculate and measure

annual kWh = active watts × scheduled hours × 365 × weekly frequency ÷ 7 ÷ 1000 + idle kWh

Measure at the wall with the intended charger, dock, display, and accessories attached. A reading taken during one workload does not cover every workload or charging phase. Active-power measurement also does not automatically measure sleep or connected-idle power; measure those modes separately or use a full-period kWh reading without double counting.

Disconnection policy

The guide does not automatically recommend unplugging or scheduled switching. Smart-plug economics appear only after the user explicitly marks safe scheduled disconnection as Yes. Confirm charging needs, updates, docks, wake functions, instructions, and electrical ratings first.

Calculate your laptop cost

Sources: ENERGY STAR computer guidance supports distinct idle, sleep, and off modes and power management; DOE measurement guidance supports representative measurement. Neither validates these inputs.

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Last reviewed: August 14, 2026