SettingsSettings for this calculationUS
The diameter of the hole or sonotube form for each post.
A common rule of thumb is a footing diameter about 3x the post's width.
The depth of concrete in the hole.
This should reach below your local frost line for posts that need to resist frost heave.
How many post footings you're pouring.
Count every post in the project that needs its own footing.
The bag size available at your supplier.
The largest bag your supplier stocks (80 lb, or 30 kg) is the most material-efficient per trip to the store, but is the heaviest to carry and mix.
Concrete bags needed
14 x 60 lb bags
- Total concrete volume
- 6.02 ft³
They open the calculator with your figures already in it
Concrete Bag Calculator: 14 x 60 lb bags — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Standard published yields for pre-mixed concrete: a 40 lb bag yields about 0.30 cubic ft, a 60 lb bag about 0.45 cubic ft, and an 80 lb bag about 0.60 cubic ft — a flat 0.0075 cubic ft per pound of dry mix, which puts the 20, 25 and 30 kg bags stocked in metric markets at about 9.4, 11.7 and 14.0 litres
- Post footing volume = pi x radius² x height, per post
Inputs used
- Footing Diameter
- 11.75 in
- Footing Height
- 24 in
- Number of Posts
- 4
- Bag Size
- 60 lb bags
Intermediate steps
- Total concrete volume
- 6.02 ft³
What this calculation does not cover
- This is a volume take-off, not a footing design. Nothing here checks bearing capacity, frost depth, or the embedment a post needs to resist wind, gate swing or soil movement — the diameter and depth you enter are taken as already decided.
- Every hole is treated as a perfect cylinder full of concrete. Nothing is deducted for the post itself, rebar or a gravel drainage base, and nothing is added for over-dig, a caved or belled bottom, or a crowned collar at grade. Augered and hand-dug holes in loose or wet ground routinely swallow more than their nominal diameter suggests.
- Rectangular pads, stepped footings and trench pours are outside this model. Entering a square pad's side length in the diameter field returns about four-fifths of the concrete it actually needs.
- Bag yield is the published nominal figure for standard pre-mixed concrete at the manufacturer's water content. High-strength, fibre-reinforced and fast-setting post mixes yield differently, and fast-setting products are often poured dry into the hole and quoted per post rather than by volume — read the yield printed on the bag you can actually buy.
- The count rounds up once, across the whole job, and assumes every bag is used in full. Mixing one footing at a time and discarding what is left in the barrow will leave you short, and there is no waste, spillage or breakage allowance in the figure.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations2
- Standard published yields for pre-mixed concrete: a 40 lb bag yields about 0.30 cubic ft, a 60 lb bag about 0.45 cubic ft, and an 80 lb bag about 0.60 cubic ft — a flat 0.0075 cubic ft per pound of dry mix, which puts the 20, 25 and 30 kg bags stocked in metric markets at about 9.4, 11.7 and 14.0 litres
- Post footing volume = pi x radius² x height, per post
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
Tools and safety for this job
To place and finish concrete, erect formwork and saw-cut cured concrete. Generic types, no brands, no prices.
Protection this work requires
- Cutting or grinding concrete, masonry, screed, tile or fibre-cement board releases respirable silica: cut wet or extract at the tool, and wear a P2/N95 respirator at minimum — a nuisance dust mask does not filter it.
- Hardwood dust is a recognised carcinogen: extract at the tool and wear a P2/N95 respirator when cutting or sanding indoors.
- Wet cement and lime burn skin and eyes painlessly until the damage is done: waterproof gloves to EN 374, safety glasses whenever the mix can splash, and never kneel in wet mix in permeable trousers.
- Saws, grinders and breakers run above 85 dB, where hearing damage accumulates and does not recover: defenders or plugs for every cut, not just the long ones.
- Breakers and grinders cause permanent nerve damage: limit continuous trigger time, keep hands warm, and stop if fingers tingle or blanch.
- Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
Show the 17 tools this job needsHide tools
Essential
Angle grinder
Bull float and edger
Circular saw
Claw hammer
Dust extractor or vacuum with a fine filter
Screed bar or rail
Shovel and spade
Spirit level
String line and pins
Tape measure
Wheelbarrow
Recommended
Chalk line
Cordless drill/driver
Floor or cut-off saw
Plate compactor
SDS rotary hammer
Optional
Power float
Also needed as materials: chalk refill, circular saw blades, cutting and diamond discs, diamond blades, drill and driver bits, SDS bits and chisels.
what each concrete tool is for, and the spec that decides which to buy where one does.