If you need punching force (f) and you already have perimeter (p), shear strength (s) and thickness (t), this calculator does the substitution for you. It suits a quick check, a homework answer you want to confirm, or any figure you need to sanity test.
What Is the Punch Force Calculator?
The punch force calculator turns perimeter (p), shear strength (s) and thickness (t) into punching force (f), so you can order the right amount of material the first time.
Material estimates are where projects go over budget. Getting the quantities right before the delivery arrives is worth more than any discount on the order.
How to Measure for the Punch Force
Measure everything in the same unit and take the largest dimension you can reasonably use rather than the average. Formwork, ground conditions and cutting waste all push the real figure above the theoretical one.
Where a plan calls for a specific thickness, check it against local building regulations before you order. The calculator reflects the relationship, not the code.
Allowing for Waste and Errors
Order a little more than the calculation suggests. The gap between the theoretical quantity and what actually arrives on site is normally waste, spillage, over-excavation and uneven grading, and all of it comes out of the same budget.
Write the figures down and compare them with what you actually used on site. That is how you build an estimate you can trust for the next job.
A Worked Example
Working through an example, with perimeter (p) set to 10, shear strength (s) set to 5, thickness (t) set to 2, the calculator returns punching force (f) of 100. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out punching force (f)?
Enter perimeter (p), shear strength (s) and thickness (t). The calculator then works through the relationship and reports punching force (f).
What does the punch force actually calculate?
It takes perimeter (p), shear strength (s) and thickness (t) and converts them into punching force (f) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter perimeter (p)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Do I have to fill in every field?
Only the fields a particular result depends on. If you leave one blank, the results that need it simply show a note instead of a number, and everything else still works.