Post Hole Concrete Calculator
Estimate concrete for round post holes using the hole diameter, concrete depth and number of holes. PlanDIYBuild returns total volume plus common bag-size equivalents for fence, deck and mailbox posts.
Post hole concrete
See how hole diameter, hole depth, number of holes and extra / waste define the concrete quantity for post holes.
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.
Materials & tools
Your project quantities with practical planning prices.
Materials to buy
Tool & supply plan
Required / common
Specialty / rent or buy
Consumables / safety
Estimated specialty rentals: $205.00
Estimated consumables / PPE: $70.00
Incremental project spend: $275.00
Common tools if starting from scratch: $470.00
Buy every tool / supply from scratch: $1,555.00
Tool prices are planning estimates. Confirm current prices, the exact installation method, manufacturer instructions and safety requirements before purchasing or renting.
$196–$428
Likely project range · 54% estimate confidence
Materials use PlanDIYBuild U.S. planning estimates. Retailer prices vary by product, store and location. Tools / rentals are planning estimates.
Cost assumptions & priced materials
Tool amounts are broad planning allowances, not current retailer or rental quotes. The incremental project-spend allowance assumes common tools are already owned and adds specialty rentals plus consumables / PPE. Reusable tools and rentals are shared across a combined saved-project budget when the same tool appears more than once; consumables / PPE remain budgeted per project. Buy-all totals use purchase allowances for every tool rather than rental allowances. Actual availability, tax, delivery, site conditions and labor may differ.
Check the method or common questions
Method, formula & assumptions
Concrete estimating basics
Formula: Volume = length × width × thickness. PlanDIYBuild 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 PlanDIYBuild what you need. We’ll add project context so the search stays relevant.