Energy vs Power: What's the Difference?

What's the difference between energy and power? Power is a rate: how fast energy is used, measured in watts (1 watt is 1 joule per second). Energy is an amount: how much is used, measured in joules or kilowatt-hours. Your electricity bill charges for energy, not power. To show why that matters, the video compares a hair dryer and a fridge. A 1,500-watt hair dryer uses more than 20 times the average power of a typical fridge (about 70 watts), yet over a year the fridge can cost about 7 times as much: about $106 against $16 at the 2025 US average of 17.23¢ per kWh. It also works out 0.25 kWh in joules (900,000 J) and clears up the common slip of saying "kilowatts per hour." Try it yourself: ▶ https://www.metric-conversions.org/energy-and-power/kilowatt-hours-to-joules.htm ▶ https://www.metric-conversions.org/energy-and-power-conversion.htm Chapters: 0:00 The puzzle 0:25 Two ideas 0:56 The hair dryer 1:51 The fridge 2:25 On your bill 2:41 A common slip 2:57 Takeaway Sources: • NIST Guide to the SI, Appendix B.9: https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9 • Penn State EGEE 102, 2.6 Common Appliance Power Ratings: https://courses.ems.psu.edu/egee102/book/export/html/2387 • Kilowatt-hours to Joules, metric-conversions.org: https://www.metric-conversions.org/energy-and-power/kilowatt-hours-to-joules.htm • EIA RECS 2020, Table CE5.3b (PDF): https://www.eia.gov/consumption/residential/data/2020/c&e/pdf/ce5.3b.pdf • EIA Electric Power Monthly, Table 5.3: https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_03 Is there anything else you'd like us to cover? Let us know in the comments below.