Comparing power requirements for several possible builds helped me understand that calculators are best used as a starting point rather than a final answer. Before buying my current PSU, I entered different component combinations into a pc wattage calculator to see how upgrades, additional drives, and cooling equipment would affect the estimated power draw. I liked being able to adjust the configuration and immediately see the impact on the recommendation. Even though the estimate looked reasonable, I still selected a power supply with some extra capacity above the calculated result. That decision paid off later when I upgraded the graphics card and added more storage. The system has remained stable during gaming sessions and long editing tasks, so I think calculators are useful, but a little extra headroom is usually worth having.