Calculator Inputs
Example Data Table
This example illustrates one typical mix scenario and the resulting yield.
| Scenario | Cement | Water | Additive | Computed yield | Estimated density |
|---|---|---|---|---|---|
| Field batch (US) | 1 sack (94 lb), SG 3.15 | 44% BWOC, water density 8.33 lb/gal | 0.5% BWOC, SG 1.20 | ≈ 8.595 gal/sack (≈ 1.148 ft³/sack) | ≈ 15.8 lb/gal |
| Workshop batch (Metric) | 1 bag (50 kg), SG 3.15 | 44% BWOC, water density 1.00 kg/L | 0.5% BWOC, SG 1.20 | ≈ 45.73 L/bag (≈ 0.0457 m³/bag) | ≈ 1.68 kg/L |
Formula Used
This calculator uses the absolute volume method. Each component contributes a volume based on its mass and density.
Yield = Vtotal / bags
Notes: In practice, entrained air, temperature, and solids packing may shift yield. Use lab-measured slurry density when high accuracy is required.
How to Use This Calculator
- Select a unit system that matches your job documentation.
- Enter cement as bags or as total mass, then set SG.
- Provide water as %BWOC for scalable mix planning.
- Add optional additives using BWOC, mass, or volume inputs.
- Press Calculate and review yield and density.
- Use Download CSV or Download PDF for records.
If you enable target sizing, the calculator estimates bags and water needed for the requested slurry volume using your current mix ratios.
Absolute Volume
Absolute volume yield starts with solids displacement. Cement volume is computed from cement mass divided by (cement SG × water density). Using SG 3.15 and 8.33 lb/gal water, one 94 lb sack occupies about 3.58 gal. Water and additives increase total slurry volume, so yield is the final volume per sack. This method stays consistent when bag weight, SG, or water density changes. It supports fast blend comparisons in practice.
Water Scaling
Water input can be set as percent BWOC to preserve ratios during scaling. For example, 44% BWOC means water mass equals 0.44 × cement mass. When cement amount doubles, water mass and water volume double automatically, which is useful for jobsite batching. If you enter direct water volume, the tool converts it to mass using water density, including brines. Both paths lead to the same volume sum internally. for reporting.
Additive Displacement
Additives may be entered as BWOC, as direct mass, or as direct volume. BWOC and mass entries require specific gravity so the calculator can estimate additive absolute volume with ρ = SG × ρwater. Volume entries already represent displacement, but providing SG lets the report estimate mass and improves density checks. Typical additives have SG near 1.05–1.25, while extenders and weighting agents can be higher. Use laboratory data whenever available.
Density Control
Slurry density is calculated from total mass divided by total slurry volume. In US units the result is lb/gal, a value for pump selection and hydrostatic estimates; in metric it is kg/L. If any additive is entered only as volume without SG, its mass is unknown, so the calculator reports density from known masses and flags the note. For field control, compare density with balance results and adjust inputs promptly.
Target Planning
Target-volume sizing turns yield into procurement numbers. After you calculate a blend, enable target volume and enter the slurry volume for the job. The tool estimates bags and cement mass using bags = Vtarget / yield. Water is scaled from the per-bag water volume, maintaining the same BWOC ratio. In practice, add a contingency factor for losses, surface lines, and cleanup. Export the sizing summary to support tickets and reports.
FAQs
What does yield per sack represent?
Yield per sack is total slurry volume divided by the number of cement sacks. It includes water and additive displacement, so it reflects the actual mixed volume available for placement, not dry materials volume.
Why is cement specific gravity required?
Specific gravity links cement mass to displaced volume using ρ = SG × water density. If SG is wrong, calculated cement volume and slurry yield shift, especially when comparing different cement blends or temperatures.
When should I enter water as BWOC instead of volume?
Use BWOC when you want a recipe that scales reliably with cement quantity. The water mass automatically tracks cement mass, which helps planning multiple batches. Use direct volume when water is measured precisely in tanks or buckets.
Do additives always need specific gravity?
SG is required for additives entered as BWOC or mass because the tool converts mass to volume. If you enter additive volume directly, SG is optional. Providing SG improves mass totals and makes the reported slurry density more representative.
Why does the calculator show a density note sometimes?
If any additive is supplied only as volume without SG, its mass cannot be estimated. The calculator then computes density from known masses only and displays a note so you can decide whether to add SG or rely on measured density.
How accurate is target-volume sizing?
Sizing assumes the same mix proportions scale linearly and that yield per bag remains constant. Add allowances for losses, line fill, and mixing variability. For critical jobs, validate yield and density with a pilot mix, then update the inputs.