About CivilStrCalc

Free structural engineering calculators — open to everyone, no registration required.

What is CivilStrCalc?

CivilStrCalc is a free, browser-based toolkit for structural engineers, students, and educators working with reinforced concrete and structural steel. Every calculation runs entirely in your browser — no data is sent to any server, no account is needed, and there are no paywalls.

The calculators implement the full provisions of the most widely used structural design codes: ACI 318-25 (United States), Eurocode 2 EN 1992-1-1 (Europe), AISC 360-22 (steel, United States), IS 456:2000 (India), and TS 500:2000 (Turkey). Each result comes with a step-by-step calculation report that can be printed or saved as a PDF.

Calculators & Tools

Reinforced Concrete Design

RC Beam Design Flexural (Whitney stress block), shear (stirrups), and torsion design for rectangular and T-section beams. ACI 318-25, EC2, IS 456.

RC Column Design P-M_x-M_y interaction diagram for rectangular and circular columns under biaxial bending. Seismic confinement checks.

Slab Design One-way flexural design and punching shear for flat-plate systems. Interior, edge, and corner columns. Stud rail and radial ring options.

Development Length Straight bar, standard hook, and headed bar development lengths. Modification factors per ACI 318-25 §25.5. Lap splice classes.

Crack Width Service-load crack width per Eurocode 2 §7.3 (w_k formula) and ACI 318 (z-parameter). Durability exposure class checks.

Spread Footing Design Bearing pressure, flexural reinforcement, one-way and two-way shear for isolated spread footings. ACI 318-25 and EC2.

Steel Structure Design AISC 360-22

Steel Flexural Design Moment capacity (φ_bM_n) for W, S, HP, C, and MC sections including compact/non-compact classification, local buckling, and lateral-torsional buckling (LTB) per AISC 360-22 Chapter F.

Steel Axial (Column) Design Compression capacity (φ_cP_n) for wide-flange, HSS, and angle sections. Effective length KL, slenderness ratio KL/r, critical stress F_cr, and section class checks.

Steel Beam-Column Design Combined axial + flexure interaction check per AISC 360-22 §H1 (H1-1a/H1-1b equations). Covers uniaxial and biaxial loading cases.

Lateral-Torsional Buckling (LTB) Detailed LTB check: unbraced length L_b vs. L_p/L_r limits, C_b factor, plastic/inelastic/elastic zones, and φ_bM_n output per AISC 360-22 §F2.

Truss Design Roof truss analysis and member design (Warren, Pratt, Howe configurations). SI and US unit modes. SHS, RHS, L-angle, HEB chord and web sections.

Retaining Wall Design

Retaining Wall — ACI (SI) Sliding, overturning, bearing, and flexural design per ACI 318-25 in SI units.

Retaining Wall — ACI (US) Same design procedure in US customary units (kips, ft, psi).

Retaining Wall — Eurocode 2 Gravity retaining wall design per EN 1992-1-1 and EN 1997-1 (Geotechnical).

Retaining Wall — TSC / TBDY Seismic retaining wall design per TS 500 and TSC 2018 §16.12, including k_h=0.4·r·S_DS dynamic increment.

Reference Tables & Guides

Steel Section Database Searchable database of IPE, HEA/B/M, W, HSS, ISMB, ISMC profiles per EN 10365, AISC, and IS 808. Custom section input.

Rebar Properties Bar sizes and mechanical properties for ASTM A615/A706, EN 10080 B400/B500, IS 1786 Fe415–Fe600, and TS 708 grades.

Concrete Properties Design properties (f_ck, f_cd, E_cm, strain limits) for all standard strength classes per ACI 318-25, EC2, and IS 456.

Unit Converter Instant conversion between SI and US customary units for force, length, stress, moment, and section properties.

ACI 318-25 Design Guide Comprehensive reference guide covering ACI 318-25 provisions for beams, columns, slabs, walls, and detailing.

AISC 360-22 Design Guide Reference guide for LRFD steel design: flexure, shear, axial, combined loading, and connection design.

Editorial Articles

In addition to the calculators, CivilStrCalc publishes in-depth structural engineering guides that explain the theory and code provisions behind common design tasks:

Who Is It For?

CivilStrCalc is designed for anyone working with structural concrete or steel:

Practising engineers who need quick, reliable preliminary calculations before moving to full analysis software.
Students studying structural engineering who want to verify hand calculations or explore how code provisions work in practice.
Educators looking for a free classroom tool that shows every calculation step transparently.
Checkers and reviewers who need an independent calculation to cross-check design outputs.

Design Philosophy

Every intermediate step is shown. We believe structural engineering software should be a transparent aid to engineering judgement — not a black box. If you cannot follow every step in the report, the result should not be trusted.

All calculations are client-side: your inputs never leave your device. The tools work offline once the page is loaded, and there is no tracking of individual calculation inputs.

Standards and References

ACI 318-25 — Building Code Requirements for Structural Concrete
EN 1992-1-1:2004 (Eurocode 2) — Design of Concrete Structures
EN 1990:2002 (Eurocode 0) — Basis of Structural Design
AISC 360-22 — Specification for Structural Steel Buildings (LRFD)
ASCE 7-22 — Minimum Design Loads and Associated Criteria
IS 456:2000 — Plain and Reinforced Concrete Code of Practice
TS 500:2000 — Requirements for Design and Construction of Reinforced Concrete Structures
TSC 2018 — Turkish Building Seismic Code
EN 10365:2017 — Hot Rolled Steel Sections
IS 808:1989 — Dimensions for Hot Rolled Steel Sections
ASTM A615/A706, EN 10080, IS 1786, TS 708 — Reinforcing Steel

Disclaimer

CivilStrCalc is intended for educational and preliminary design purposes only. All results must be independently verified by a licensed structural engineer before use in any construction project. The site makes no warranty as to the accuracy or fitness for purpose of any calculation result. See our Terms of Use for full details.

Contact

Questions, error reports, or suggestions are welcome at info@civilstrcalc.com.