I always consider four factors in estimating software cost - the scope of the task - the resource/people you have - the confidence in the resource/people -

I always consider four factors in estimating software cost - the scope of the task - the resource/people you have - the confidence in the resource/people - and the dependency on both the resource and the task Estimation goes wrong in many ways. In my experience, I categorize as follow: - estimated by non-technical PM, unable to gauge technical/business complexity - estimated too early in development life cycle. Often time someone come up with idea X then ask right away "shouldn't be difficult, how long will it take" - no view on team member's productivity due to lack of measurement or measuring the wrong thing - not considering dependency in the development cycle. e.g. The question "whether our only backend engineering available for the task" is often omitted - not considering testing, documentation, 3rd party integration/procurement, maintenance and deployment cost The common practise of coming up a number, then double, or maybe triple it up to make the estimation does not address why estimation is off. Mis-estimation is a symptom. The cause and the cure lies in the people