You're absolutely right — watt is a unit of power, not energy. To make a meaningful comparison, we need to estimate how much energy (in joules) each system uses to solve the same task.
Let’s define a representative task: answering a moderately complex question.
1. Human Brain
Power use: ~20 watts (on average while awake)
Time to think: ~10 seconds to answer a question
Energy used:
20
watts
×
10
seconds
=
200
joules
20watts×10seconds=200joules
2. ChatGPT (GPT-4)
Estimate per query: Based on research and datacenter estimates, GPT-4 may use:
Around 2–3 kWh per 1000 queries, which is 7.2–10.8 megajoules
Per query:
7.2
MJ
1000
=
7200
joules
1000
7.2MJ
=7200joules per response (lower bound)
10.8
MJ
1000
=
10
,
800
joules
1000
10.8MJ
=10,800joules per response (upper bound)
Comparison
Human: ~200 joules
ChatGPT: ~7,200 to 10,800 joules
Conclusion:
The human brain is about 36–54 times more energy-efficient than ChatGPT at answering a single question.
