You ordered 50 bags for a 10×10 patio at 4 in. The math said ~56 of 80 lb before waste — closer to 62 with 10%. Forms are set. The mixer is warm. The pallet is light by a dozen. That is a second store run while the first bags start to stiffen.
This is the concrete bag calculator you use on the job tomorrow, not a lecture. Not theory. Yards and bags you take to the yard — slab first, then footing, pier, stairs when the pour is not a rectangle.
Free does a slab. Pro is $9.99 a month for footing, cylinder / pier tube, and stairs. Worth $9.99 if the week has more than one shape. After the first pour count, the next app in the suite was already open: Fence Takeoff Master for the posts those holes belong to — or Rebar Takeoff Master for the mesh under the pad.
What a concrete calculator app actually has to do
Most “best concrete calculator” pages stop at cubic yards. A concrete calculator review that matters has to survive the next morning: dirty thumbs, a tape you already walked, a bag count you can read at the pallet without translating a formula.
Concrete Mix Master is a phone-first PWA. Add it to the Home Screen. English UI. US, UK, AU, NZ, and CA bag sizes by region you pick — it never reads your location. Feet/inches or metres/millimetres. Offline after the first load. No login. No account. Data stays on the device unless you export a backup.
You enter a pour — length, width, thickness for a slab, waste percent, optional copies. You get cubic yards (and metres) plus bag counts for the region bag sizes. That is the product. Not a lecture on mix design.
The slab math is the same volume we already published: length × width × thickness, convert to cubic feet, divide by bag yield, round up, add waste. A 10×10 at 4 in is about 56 bags of 80 lb before waste — closer to 62 with 10%. If you want the chart on paper, use How Many Bags of Concrete Do I Need? The app is that count plus the shapes Free does not cover.
I used it on the job the next morning. That is the only review that matters. If the number only works at a desk, it is homework. If it works in the truck, it is a takeoff.
Free vs Pro — no mystery
Free: one slab (or patio / sidewalk / pad). Length × width × thickness. Region bag table. Waste you can edit (default 10%). Sample 10×10 patio load so you can sanity-check before your own numbers. Feet/inches or metres/millimetres. JSON backup on this device.
Pro, $9.99 a month: everything in Free, plus footing, cylinder / pier tube, and stairs. Those are the shapes that show up when the pour is not a neat rectangle — strip footings under a wall, Sonotube-style piers for a deck, a small stair pour where rise and run eat volume you cannot eyeball.
Footings and piers are the line most free web calculators skip or bury behind another page. If the week is only a pad, Free is the product. If the week has a footing and three tubes, Free will feel like a demo. Pro is the working copy.
There is no branded quote PDF in this app the way Fence Takeoff Master Pro has one. Concrete Mix Master Pro is about more shapes, not letterhead. If you need a branded fence quote, that is a different app in the suite.
What it is not
Estimate only — not engineering or building-code advice. It does not know your subgrade, frost line, slump, or brand bag yield on the pallet you actually bought. Manufacturer yields vary. Measure twice. Buy a spare bag.
It is not ready-mix dispatch. It will not call a truck, price a short load, or book a pump. If the pour is big enough for a ready-mix minimum, use the yards figure to talk to the supplier — do not treat bags as the only path.
It is not STACK or OneCrew. There is no schedule, no crew, no invoice, no client portal. If you needed full estimating software, this is the wrong tab. If you needed a concrete bag calculator you can open without an account, this is the right tab.
It is not five country apps. One English UI. Price in USD. Paying markets: USA, UK, Australia, New Zealand, Canada. No AI. Bag yields are static tables you pick a region for.
Is $9.99 worth it?
If you pour one patio a year, Free is the product. One slab, waste, bag count, go to the yard.
If you pour more than a rectangle — footings, pier tubes, a stair pour — Pro is the product. Those shapes are how a real week of small pours is counted. The second store run for a short pallet costs more than a month of Pro in time, fuel, and a stiffening first batch. That is the offer.
Worth $9.99 on a week with two shapes. Not worth pretending it replaces a licensed engineer or a ready-mix quote. No fake star widget. No invented “customers say.” The test is whether you used it on the job the next morning. I did.
The series
Concrete Mix Master is one app in EBN Build Calculators. After the bag count, the next number is often the holes or the mesh. I already opened Fence Takeoff Master when the pour was post holes, and Rebar Takeoff Master when the slab needed bars. Same idea across the suite: phone-first, offline, estimate only — cut lists, stairs, sheets, framing, roofing, decks, masonry, rebar.
If you still want the long-form bag chart, read how many bags of concrete you need. Then come back and run the pour. Theory is the chart. The job is the list.
Bottom line
Concrete Mix Master is a concrete calculator app you can use on the pour tomorrow. Not a textbook. Not STACK. Free for a slab. Pro for footing, pier, and stairs at $9.99 a month. Punch the tape. Take the bag count to the yard. Open the next app in the series when the holes or the mesh need their own number.
Open Concrete Mix MasterEstimate only — not engineering or building-code advice. Not a contract. Not ready-mix dispatch.