Measure inside the forms
The calculator multiplies the three numbers you type. This page is about getting those three numbers off the ground. It does not choose a thickness for you.
Length and width
Put the tape inside the forms, not on the outside boards. If you measured in inches, divide by 12 and write feet before you type. Write the unit next to the number.
Thickness in more than one spot
Measure inches from the top of the form down to the subgrade. Check more than the middle. If one spot is deeper, write that down. Yardslip will not tell you which thickness is strong enough. Ask the building department or a licensed designer.
What you may also bring
An allowance, if you want extra volume, as a percent you choose. The cubic feet printed on the bag, if you might buy bags. A low and a high dollar per square foot from quotes you already have, if you want a range. A single quoted total, if you want to see it beside that range.
| Field | Unit | Where it comes from |
|---|---|---|
| Length | Feet | Inside the forms, the long side |
| Width | Feet | Inside the forms, the short side |
| Thickness | Inches | Form top to subgrade, more than one spot |
| Bag yield | Cubic feet | The bag you plan to buy, not a remembered chart |
| Rates | Dollars per square foot | Quotes you already have. Leave blank if you have none |
Questions
Does the slip include a gravel base?
No. The yards are the concrete from length, width, and thickness. Base, forms, and steel are separate buys.
Is the example thickness a rule?
No. Five inches on the calculator is filled in so the arithmetic is visible. Replace it. Local thickness rules are unknown here. How to find out: the authority having jurisdiction, or a licensed designer.
Where do the dollars come from?
Only from the low and high you type. Yardslip has no price list. A blank rate stays blank.
Will these measurements be uploaded?
This page runs the arithmetic in the browser. It does not send dimensions or totals to a server.
What about a post hole or a round column?
Not on this calculator. Measure those on paper until that shape is added. Stairs are the same: wait until the shape is specified.