How item weight and caps value work
Compare an item's weight with the materials or equipment you need before deciding what to keep. A listed base caps value is not a quote for what a vendor will pay.

Read the Deathclaw Hide entry for the item shown above. Use recorded inventory to keep its carried and stashed amounts separate, then compare its salvage yield with what your crafting plan still needs.
Use the carried and stash weights shown in your game when perks or modifications change them. The inventory planner keeps those two weights separate, so a carried-weight adjustment does not also reduce the recorded stash weight.
For junk, compare its scrap yield with your crafting plan. Some recipes need an item intact. Scrapping that item can provide materials while leaving the original recipe short of an ingredient.
Combine your recipes in the crafting planner before collecting supplies. Record what you already have, review the remaining materials, and follow each material to the junk that supplies it. Confirm recorded salvage after scrapping in the game.