help estimating hours

Hi, I've been a php programmer for quite a while, but working salaried for a company. So while I'm confident in my skills to complete a task, I've never really paid attention to the number of hours a project took.

As I'm making the transition to freelance, I'm finding out that the hardest part for me is estimating my hours. I've been asked to bid on a fairly large ecommerce site and I was wondering roughly how many hours others would consider this sized project. I will be doing all of the php programming including a shopping cart, checkout, user database, and admin console (including product management), but not the design of the site. (I'm unsure yet if I'll be working from images, or from html and css already built)

I know this isn't a very detailed description of the project, but I'm just looking for some rough ideas of what you would charge.

Thanks

Wow... it's hard to say. Everyone works at different rates. Will you be billing for study time? Are you using a framework or CMS like Drupal?

Oops, duplicate entry

If your coding the ecommerce from scratch, and not using a CMS...I would say it could take anywhere from 10 hours to several days depending on how fast you work.

The application has some unique properties and will be made from scratch in php.

Originally Posted by uNiT If your coding the ecommerce from scratch, and not using a CMS...I would say it could take anywhere from 10 hours to several days depending on how fast you work.

An Ecommerce site in ten hours? Good luck with that.

No one can estimate hours for you because we dont know how long tasks will take you.

I feel your pain. I'm in the same boat myself, just starting to do some freelance work, and I'm not used to estimating my hours. The best advice I can give is to sit down with a pencil and paper and list out everything that you'll have to do, step by step, then make your best guess as to how long it will take you to do each step. You're the only person who really knows how you work, so you can't really go by a "one size fits all" approach.

Just as ditch said, it's extremely beneficially to know exactly what you're going to do and break it down as small as possible, or at least to the point where it's obvious how long something will take. You'd should also add plenty of padding since something always has to go wrong that takes you longer than expected. I usually double the amount of hours I think it's going to take and it's usually always on the dot or more or less 15% off in either direction.

But one thing is key is that you really know what you're going to do. For instance, for the shopping cart, are you going to work with some shopping cart that already done, but modify it to your needs or are you going to make a shopping cart from scratch? Building a shopping cart from scratch would defintely take you a lot longer than using something that'll give you a foundation (PayPal or Authorize.Net API, etc.).

It's very hard to calculate a time frame for such a large project. You may get into complications, etc. An e-commerce site from scratch would definitely take longer than 10 hours, depending on what features are needed it could take you hundreds of hours to complete. With an e-commerce system (usually) you have to connect it to a payment gateway. It's best to let the client know it's a large project, and don't promise anything if you don't know what your getting into.

This is how I do it.

For example, say my hourly rates for php work was $80

I would then get the client to write up, or we both go through all the features needed for the project. And you both need to be exact.

Once you have a list of features, write at the side of each one, how long it would take you to do in hours.

Then do a calculation and quote the client.