Calculating price based on length of hire.

[nostromo]

Question related to estimating section of this forum.

I have a project that was meant to remain on site for 12 weeks.
Now there was a change in scope of works for my client and they would like to change it to 26 weeks. We already got the job and project will start in next few weeks. But we have to adjust our quote to allow for additional weeks effectively doubling time our material will spend on site.
Is there a formula any one is using to work it out?

 

[SF Admin]

We normally charge 5% of contract value per extra week over 12 weeks which would equate to 60% extra.
However if someone is asking for 26 weeks up-front then you may want to discount that depending on how much you'd like the business.

Be interested what others do too.