Acknowledgment. First of all, thanks to my friend Chris Souder at Cal State Chico – I based this article off of a conversation with him plus his article entitled Can Using Form Ratios Improve the Accuracy of Estimating Structural Concrete?

Executive Summary. Now, the summary. Form Ratio serves many companies as an indicator of cost (the higher the ratio, the higher the cost). Consider implementing this ratio into your takeoff and estimating procedure.

So, what exactly is a Form Ratio? The Form Ratio is a quantitative number which results from takeoff of a concrete element. The definition of Form Ratio follows:

How do I calculate it? The process by which this number is generated is simple:

1. Separate your concrete elements for individual takeoff (i.e. footing, slab on grade, suspended slabs, small walls, large walls, flatwork, curbs and gutters, etc.).
2. Perform the takeoff for each element – this will result in the square feet of contact area of the forms (this is called SFCA).
3. Calculate the neat volume of concrete for each element (“neat” volume excludes any waste).
4. Calculate the Form Ratio as detailed above.

You’re done.

Why do I care? So now you have each of your elements of concrete taken off and you’ve calculated your Form Ratios. It may look something like this:

You care because if you calculate these ratios, and relate them to other historical work completed, it may serve as a somewhat reliable indicator of cost.

Engineers love data and project managers love metrics – this ratio combines the two.

My story. I have a concrete takeoff form from 25+ years ago. I think when it was given to me, it was already 10 years old. It has down in the corner “Form Ratio”, but I never tracked this number. I love taking off concrete and I’d certainly encourage any companies to incorporate and pay attention to Form Ratio. It’s just so easy to calculate and track and could lead to better estimating.  Work safe!