Post Hole Concrete Calculator
Estimate concrete for round post holes using the hole diameter, concrete depth and number of holes. BuildGauge returns total volume plus common bag-size equivalents for fence, deck and mailbox posts.
What you'll need
Key purchase quantities from the same complete BOM used below.
The preview and copied list come from the shared BOM. Planning estimate — verify product sizes, structural requirements and local conditions before purchasing.
Check the method or common questions
Method, formula & assumptions
Concrete estimating basics
Formula: Volume = length × width × thickness. BuildGauge converts thickness from inches to feet, then converts cubic feet to cubic yards. Bag estimates use the stated approximate yield for each common bag size.
Worked example: Example: a 10 × 12 ft slab at 4 in thick has 40 ft³ of geometric volume before extra material. Divide cubic feet by 27 to convert to cubic yards.
Before you buy: Concrete projects commonly need extra material for grade variation, spillage and imperfect measurements. Use the adjustable extra-material percentage and confirm the yield printed on the mix you plan to buy.
Post Hole Concrete Calculator FAQ
Should I order exactly the calculated amount?
Usually no. Real forms, subgrade and measurements are rarely perfect. The calculator lets you add extra material so you can plan above the geometric minimum.
Are concrete bag yields exact?
No. Bag yield varies by product. Treat the displayed bag counts as planning estimates and verify the yield printed on the specific mix before buying.
Continue your Concrete project
Use the Concrete planning hub for related calculators and quick-reference guides.
Useful products for this project
Photos are representative examples of the item type—not the exact Amazon listing. Amazon links open current search results so you can compare brands, sizes and prices.
Representative product photo
Representative product photo
Representative product photoFind something for this project
Tell BuildGauge what you need. We’ll add project context so the search stays relevant.