Quick answer
With a chosen 1.54 dry factor and 1,440 kg/m³ loose cement density, a 1:2:4 quantity model for 1 m³ gives 316.8 kg cement, 0.44 m³ sand and 0.88 m³ aggregate before loss. That is 6.336 × 50 kg cement bags, rounded to 7 if buying for this batch alone.
What the 1.54 factor does
The model multiplies wet finished volume by a chosen dry-volume factor before dividing it into volumetric parts. Dry loose materials contain voids, and their volumes do not simply add to the finished concrete volume. A factor such as 1.54 is an estimating convention, not a measured property of every sand and stone combination.
Aggregate grading, moisture, compaction and actual batch yield affect the result. Use the supplier's approved design or a measured trial yield for procurement where available. Keep extra loss separate, and do not assume a factor already includes your site wastage.
Compare two nominal ratios
For 1:2:4, the total number of parts is 7. Cement volume is 1 × 1.54 ÷ 7 = 0.22 m³; sand is 0.44 m³ and aggregate 0.88 m³. Cement mass uses the explicitly selected loose bulk density: 0.22 × 1,440 = 316.8 kg.
For 1:1.5:3, there are 5.5 parts. Cement is 0.28 m³, sand 0.42 m³ and aggregate 0.84 m³. At the same illustrative cement density that is 403.2 kg, or 8.064 bags of 50 kg. Round up only when converting the complete purchase into whole bags.
| Volumetric ratio | Cement kg | 50 kg bags, unrounded | Sand m³ | Aggregate m³ |
|---|---|---|---|---|
| 1:2:4 | 316.8 | 6.336 | 0.440 | 0.880 |
| 1:1.5:3 | 403.2 | 8.064 | 0.420 | 0.840 |
Worked example: 5 m³ footing takeoff
Suppose the approved drawing gives a total net footing volume of 5 m³ and you are comparing the 1:2:4 quantity model above. Before loss, multiply the unrounded quantities by five: 1,584 kg cement, 2.20 m³ sand and 4.40 m³ aggregate. Cement is 31.68 bags, so the purchase is 32 whole 50 kg bags.
If you explicitly choose a separate 5% loss allowance, the model becomes 1,663.2 kg cement, 2.31 m³ sand and 4.62 m³ aggregate. That is 33.264 bags, rounded to 34. Do not multiply the earlier rounded seven-bag figure by five; that would introduce unnecessary repeated rounding.
The equivalent wet volume is approximately 6.54 yd³. Keep aggregate loose volume distinct from delivered tonnes and compacted volume. Converting to mass requires the supplier's corresponding bulk density.
Cement bags and complete concrete bags differ
A 50 kg cement bag is only the binder. A bagged concrete mix contains cement, aggregate and other dry constituents, and has its own finished yield. Use the concrete-bags calculator with the exact product yield for a complete premix.
The existing concrete-mix calculator accepts cement-bag loose volume in ft³ even in metric mode. With the example density and 50 kg bag, 50 ÷ 1,440 = 0.034722 m³, approximately 1.226 ft³. That setting is a calculated model input, not a universal yield for all cement bags.
When an approved mix design is needed
Strength, durability and workability depend on more than a nominal ratio. Water content, water-cement ratio, aggregate, exposure requirements, production control and curing matter. Structural footings should follow the responsible designer's specification and the required testing process.
Do not use this page to choose a water dose or make a strength claim. Ask the concrete supplier for the approved mix reference, production and delivery records, and sampling requirements. A measured quantity is one input to that process, not evidence that a homemade recipe satisfies it.
Questions people ask
Does 1:1.5:3 automatically mean M20?
No. A volumetric ratio does not establish tested compressive strength. Use an approved design and the required quality-control process.
Is the dry factor always 1.54?
No. This is an editable estimating convention. Actual yield depends on materials and batching; use verified mix or trial information when available.
Why are seven bags per m³ not multiplied for every job?
Seven is a rounded one-batch purchase. Multiply unrounded material demand by the total volume first, then round the final bag count once.
Sources and calculation basis
Source links support the specific technical points below. Worked quantities are Construclytic calculations using the assumptions shown above. References do not establish local prices or replace the project specification.
- NRMCA: ordering and hot-weather concrete resourcesTechnical background: CIP 31 covers ordering, CIP 12 hot-weather placement. This is not a Qatar price source.
- QUIKRETE Concrete Mix No. 1101 product dataProduct-specific approximate yields: 60 lb = 0.45 ft³; 80 lb = 0.60 ft³. Check your actual bag.