Short answer: Class A — a 1:2:4 mix by volume (one part cement, two parts sand, four parts gravel) is the standard structural mix on Philippine residential sites, and it takes about 9 bags of 40kg cement, 0.5 m³ of sand and 1.0 m³ of gravel per cubic meter of finished concrete. Richer and leaner mixes run from Class AA (1:1.5:3, ~12 bags) down to Class C (1:3:6, ~6 bags).
The part almost nobody explains: the letters AA/A/B/C mean two completely different things in the Philippines depending on whether you're reading a site estimator's table or a DPWH specification. In the site-mix tradition the letter is the recipe. In DPWH's Item 405 the letter designates the application and aggregate grading — and carries no strength on its own, because the strength is specified separately. Mixing the two systems up is covered in detail below, because it is expensive on a real project.
Class AA (1:1.5:3): 12 bags · Class A (1:2:4): 9 bags · Class B (1:2.5:5): 7.5 bags · Class C (1:3:6): 6 bags — all with ≈0.5 m³ sand and ≈1.0 m³ gravel per m³.
Site mixing in the Philippines is proportioned by volume, traditionally measured with a wooden mixing box or by the sack. The four standard classes below come from the estimating tables used across the industry — the same factors our cement price guide calculator uses:
| Class | Ratio (C:S:G) | 40kg bags/m³ | Sand | Gravel | Typical use |
|---|---|---|---|---|---|
| AA | 1 : 1.5 : 3 | 12.0 | 0.50 m³ | 1.00 m³ | Water tanks, cisterns, septic vaults, heavily loaded columns, precast |
| A | 1 : 2 : 4 | 9.0 | 0.50 m³ | 1.00 m³ | General structural — footings, columns, beams, suspended slabs |
| B | 1 : 2.5 : 5 | 7.5 | 0.50 m³ | 1.00 m³ | Non-structural — slab on grade, pathways, mass fill |
| C | 1 : 3 : 6 | 6.0 | 0.50 m³ | 1.00 m³ | Lean concrete — footing blinding, levelling, non-load-bearing fill |
Figures are for 40kg bags, the standard Philippine bag size. For 50kg bags, multiply by 0.8 — Class A becomes about 7 bags per m³. These are theoretical quantities with no wastage allowance; see the calculator below to add one.
It surprises people that a 1:2:4 mix and a 1:3:6 mix both call for 0.5 m³ of sand and 1.0 m³ of gravel per cubic meter. The reason is that concrete volume is set by the aggregate skeleton, not by the sum of the ingredients. Cement paste and water occupy the voids between sand and gravel particles rather than adding to the stack height. Going from Class C to Class AA doubles the cement while the aggregate volume barely moves — you are filling the same voids with richer paste.
Enter your pour volume and mix class for cement, sand, gravel, mixing water, and indicative material cost.
This is the single most useful thing on this page. The Philippines has two unrelated systems that both use the letters A, B and C for concrete, and they do not line up.
System 1 — Volumetric mix classes (site mixing)
The estimating tradition described above. The letter describes a recipe by volume, ordered from richest to leanest: AA is richest, C is leanest. There is no strength guarantee attached — the letter tells the crew what to shovel, not what the concrete will test at.
System 2 — DPWH Standard Specifications, Item 405
Used on government infrastructure and on many private projects whose specifications were copied from DPWH documents. Here the letter identifies what part of the structure the concrete is for, and which coarse-aggregate grading it uses — not how strong it is. The current specification, issued as DPWH Department Order No. 32, series of 2025, provides five classes: A, B, C, P and Seal (with a Class Y appearing in the pay items for box girders).
| DPWH Item 405 class | Where it's used | 28-day strengths in the pay items |
|---|---|---|
| Class A | All superstructures and heavily reinforced substructures — slabs, beams, girders, columns, arch ribs, box culverts, reinforced abutments, retaining walls, reinforced footings | 20.68 → 50.0 MPa |
| Class B | Footings, pedestals, massive pier shafts, pipe bedding, and gravity walls, unreinforced or with only a small amount of reinforcement | 16.50, 18.0, 20.68, 27.58 MPa |
| Class C | Thin reinforced sections, railings, precast reinforced concrete piles and cribbing, and filler in steel grid floors | 20.68, 27.58 MPa |
| Class P | Pre-stressed concrete structures and members | 34.47 → 50.0 MPa |
| Seal | Concrete deposited in water | specified per project |
Classes and uses quoted from Section 405.1.2 of the DPWH Standard Specification for Item 405 — Structural Concrete (Department Order No. 32, s. 2025). The strength column lists the values that actually appear in that Order's pay-item schedule.
In the site-mix table, Class B (1:2.5:5) is a lean non-structural mix you would never put in a column. In DPWH Item 405, Class B is engineered structural concrete for footings and gravity walls, procured at a stated strength anywhere from 16.50 to 27.58 MPa. Note what that means: DPWH Class B and Class C overlap in strength — both are available at 20.68 and 27.58 MPa — so a DPWH class letter on its own tells you nothing about how strong the concrete is. The strength is the number written beside it, and under Section 405.3.1 it has to be proven by trial mixes meeting the strength specified on the approved plan. If a drawing, bill of quantities, or supplier quote just says "Class B", ask which system it means and what strength is specified before anyone batches anything.
Mix ratios get all the attention, but the water-cement ratio does more to determine final strength than the sand-to-gravel proportion ever will. A workable structural mix sits at roughly a 0.45 to 0.55 water-cement ratio by weight — about 18 to 22 litres of total water per 40kg bag.
The word total is the catch. That figure includes water already carried by damp sand and gravel, which on a Philippine site after rain can be substantial. Aggregate stockpiled in the open during the wet season can carry several litres per cubic meter, and none of it is visible at the mixer.
Why crews add water — and what it costs
Extra water makes concrete easier to shovel, pump and finish, so there is constant pressure to add "just a little more" at the mixer, especially in afternoon heat. The problem is that the added water does not disappear — it leaves capillary voids as the concrete cures.
As a rule of thumb, pushing a 0.50 mix to 0.65 can cost roughly a third of the compressive strength, on concrete that looks completely normal once it has set. Nothing about a finished column tells you this happened; it only shows up in a cylinder break, or in a crack years later.
The correct fix for stiff concrete is a water-reducing admixture (plasticiser) or a revised mix design — never a hose at the mixer.
A 1:2:4 ratio written on a drawing means nothing if the crew is counting shovels. Shovel loads vary enormously with material moisture, shovel size, and how tired the person is by mid-afternoon.
Volumetric proportioning is a practical, widely used approach for small residential pours, and this page gives you the standard tables for it. But it is important to be straight about what it is: a proportioning rule of thumb, not a demonstration of strength.
Under NSCP 2015's structural concrete provisions, a specified compressive strength (f'c) is established through mix design and verified by 28-day cylinder tests — not by declaring a volumetric ratio. Two crews using the same 1:2:4 recipe with different aggregate gradings, different sand cleanliness, and different water discipline will produce measurably different concrete.
You need a designed mix with cylinder testing, rather than a ratio alone, whenever:
If you're weighing site-mix against ready-mix for a real pour, the crossover is mostly about volume and continuity — see our ready-mix concrete price guide for the cost comparison, and the NSCP footing size calculator if you're still sizing the elements you're about to pour.
The volumetric class factors on this page are the standard Philippine estimating figures, cross-checked against published Philippine construction cost references and matched to the calculator in our cement price guide so the two pages never disagree. Independently published contractor tables land within roughly 5% of these numbers. The DPWH material on this page is taken from the current specification — DPWH Department Order No. 32, series of 2025, "DPWH Standard Specification for Item 405 — Structural Concrete", dated 10 February 2025 — read directly from the Order published on dpwh.gov.ph, not from secondary summaries. Be careful with older sources: pre-2025 write-ups of Item 405 commonly quote a single fixed strength per class (for example "Class B = 16.5 MPa, Class P = 37.7 MPa"), which no longer reflects the pay-item schedule in force. Item 405 is revised by department order from time to time, so confirm the current edition on any government-funded project.
What is the standard concrete mix ratio in the Philippines?
Class A — 1:2:4 by volume — is the standard general-purpose structural mix. Class AA (1:1.5:3) is used for tanks and heavily loaded members, Class B (1:2.5:5) for non-structural work, and Class C (1:3:6) for lean concrete and fill.
How many bags of cement per cubic meter of concrete?
For 40kg bags: Class AA about 12, Class A about 9, Class B about 7.5, and Class C about 6 — each with roughly 0.5 m³ of sand and 1.0 m³ of gravel per cubic meter.
Is DPWH Class B concrete the same as site-mix Class B?
No. Site-mix Class B is a recipe (1:2.5:5). DPWH Class B, under Item 405 as revised by Department Order No. 32 s. 2025, identifies an application and aggregate grading, with strength specified separately — 16.50, 18.0, 20.68 or 27.58 MPa. DPWH Classes B and C overlap in strength, so the letter alone tells you nothing about how strong the concrete is.
How much water per bag of cement?
About 18–22 litres per 40kg bag, a 0.45–0.55 water-cement ratio by weight. That total includes water already in damp sand and gravel, so reduce what you add at the mixer on a wet site.
Can I use a volumetric mix ratio for structural concrete?
It's common and generally acceptable for small residential pours, but a specified f'c can only be demonstrated by a designed mix and 28-day cylinder tests. If your drawings specify a strength, you need testing, not just a ratio.
Mix class is a downstream decision — it follows from the loads, the spans, and the exposure conditions your structure has to handle. AEDO's engineers specify concrete strength as part of a complete structural design, sealed by a licensed civil engineer.