Mechanical & Civil Engineering
Concrete Crack Width Control Calculator
Estimate the maximum surface crack width of reinforced concrete under service loads per ACI/Eurocode approaches.
Your inputs
Change any value to update the result instantly.
Estimated crack width
0.008 mm
Allowable crack width
0.3 mm
Utilization ratio
0.03
Steel service stress
240 MPa
What this calculator does
Concrete Crack Width Control Calculator: Applies the standard civil and geotechnical relationship for this problem so the flow, pressure, settlement or capacity can be worked out from measured site inputs.
What your result means
The headline figure is the hydraulic or geotechnical quantity implied by your site inputs. Compare it against the design criteria in the applicable code before acting on it.
Formula and working
w = k × fs × √(dc × A) / Es (Gergely-Lutz style)
- 1
Collect the inputs
Service stress in steel (fs) = 240 MPa; Concrete cover to bar (dc) = 40 mm; Effective tension area per bar (A) = 15,000 mm²; Steel elastic modulus (Es) = 200,000 MPa
- 2
Apply the formula
w = k × fs × √(dc × A) / Es (Gergely-Lutz style)
- 3
Result
Estimated crack width = 0.008 mm
Frequently asked questions
Symbols and assumptions
- steelStress
- Service stress in steel (fs) (MPa)
- coverThickness
- Concrete cover to bar (dc) (mm)
- effectiveArea
- Effective tension area per bar (A) (mm²)
- steelModulus
- Steel elastic modulus (Es) (MPa)
- • Steady-state, single-phase conditions are assumed unless the page says otherwise.
- • Site inputs (soil properties, flow, roughness) come from the user's own survey or testing.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • This is an educational estimate for learning and checking, not a design deliverable.
- • Real design must follow the governing code or standard for your jurisdiction and be reviewed and signed off by a qualified engineer.
- • Safety factors, load combinations and material certification are the responsibility of the designer, not of this page.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
Tell us if a formula, unit, explanation, or result needs attention. Your message will include this calculator’s name and page.
Related calculators
Prestressed Concrete Tendon Loss Calculator
Estimate total prestress losses in a post-tensioned tendon from elastic shortening, friction, and long-term effects.
Steel Column Base Plate Thickness Calculator
Determine the required base plate thickness for a steel column per AISC Design Guide 1 methodology.
Broad-Crested Weir Discharge Calculator
Calculate the discharge over a broad-crested weir given head and crest width.
Coulomb Earth Pressure (Sloping Backfill) Calculator
Calculate active earth pressure on a retaining wall using Coulomb's theory with a sloping backfill.
Culvert Inlet vs Outlet Control Capacity Calculator
Estimate culvert discharge capacity under inlet control and outlet control conditions for sizing.
Foundation Settlement (Immediate & Consolidation) Calculator
Estimate immediate elastic settlement and primary consolidation settlement of a shallow foundation.