> you can normally give some idea, or break the task down into stages That requires the skill to actually do that. If you don't have the skill to do a thing,

> you can normally give some idea, or break the task down into stages That requires the skill to actually do that. If you don't have the skill to do a thing, then claiming you've done it isn't professional. In thinking about this, it suddenly occurs to me that in other domains, the professional thing to do would be to call in someone who does. A medical doctor doesn't know how to properly operate imaging equipment and so she calls in a radiologist. A general contractor isn't really skilled at building a septic system and so sub-contracts to someone who does know how to do that. > mostly comes down to is experience. I think the answer to "What should I do when asked for an estimate when I don't know how to make one?" might actually be to call in the help of a more senior engineer to talk through the project with you and guide you to producing the estimate. This still requires you to have the backbone to say "I don't know." and "I need help." Then, you can gain the experience of producing a reliable estimate and seeing what questions need to be asked when doing so.