Footing Size Calculator
Calculate required footing dimensions from soil bearing capacity and column load
Free web-based calculator that determines the minimum footing size needed to support structural loads on given soil conditions. Calculates required footing area, dimensions, and depth based on soil bearing capacity, applies ACI 318 design checks, and provides frost line recommendations.
- Pricing
- free tier
- Alternatives
- ClearCalcs, dRofus, Kolega
- Who it's for
- Architecture, Structural Engineering, Foundation Design
Why This Tool Exists
Architects and early-stage designers typically spend 1-3 hours manually sizing foundation footings using spreadsheets, calculators, or rough estimating methods. Without a systematic approach, footing sizing varies dramatically based on soil type (clay vs. sand) and bearing capacity assumptions, leading to either undersized footings that fail soil bearing checks or oversized footings that inflate construction costs. Designers must cross-reference soil bearing capacity data, local frost line requirements, IBC tables, and footing dimension charts from multiple sources. Geotechnical reports are often unclear or unavailable during schematic design, forcing designers to use conservative estimates that don't match the actual site conditions. This manual process introduces calculation errors, delays design progression, and often requires structural engineer rework to confirm footing adequacy.
Instant footing sizing using the fundamental equation: Required Area = Load (lbs) / Allowable Soil Bearing Pressure (psf). Calculates required footing area, suggests square vs. rectangular dimensions, applies ACI 318 sizing rules for column offset and soil contact pressure verification. Includes lookup tables for typical soil bearing capacities (loose sand, dense sand, soft clay, stiff clay) and local frost line depths by region. Provides preliminary design guidance that architects can use in schematic design before engaging structural engineers. Reduces footing sizing from hours to minutes, identifies when site-specific geotechnical investigation is required, and helps architects estimate concrete volume and reinforcement needs for early cost planning.
How You Use It
Data Transparency
Exactly what this tool uses and how
N/AUse Cases
- ·Architects sizing foundation footings during schematic design when structural engineer is not yet engaged
- ·Early project cost estimation: architects calculating concrete volume and material costs for budget planning
- ·Design team coordination: architects quickly answering structural team questions about footing feasibility
- ·Client presentations: architects estimating foundation costs before schematic design approval
- ·Renovation projects: architects verifying that existing soil conditions support additional loads from building modifications
- ·Structural engineers validating preliminary designs or checking student work (educational use)
- ·Contractors and estimators preparing material takeoffs and concrete orders from architectural plans
- ·Building officials and AHJ reviewers checking footing adequacy against IBC requirements
- ·ARE5 exam preparation: students learning footing design methodology and ACI 318 requirements
- ·International design: engineers in other markets (Canada, Australia, Eurocode jurisdictions) learning US-based ACI footing methodology
Pricing
Sources & Research NotesResearch date: 2026-04-04
- https://skyciv.com/concrete-footing-calculator/
- https://webstructural.com/footing-designer.html
- https://www.asdipsoft.com/free-footing-calculator/
- https://www.concretenetwork.com/concrete/footing_fundamentals/footing_dimensions.htm
- https://footingpad.com/sizing-calculator/
- https://www.hunker.com/13425697/how-to-calculate-footing-size/
- ACI 318-19: Building Code Requirements for Structural Concrete (American Concrete Institute)
- IBC 2021: International Building Code, Chapter 4 (Foundations)
- IBC Table 403.3: Minimum Depth of Footings Below Frost Line
- ASCE 7-19: Minimum Design Loads and Associated Criteria for Buildings and Other Structures
- Terzaghi Bearing Capacity Theory (classical soil mechanics reference)
- AISC Steel Construction Manual (for embedded column design)
- https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/state/?cid=nrcs143p2_002207 (Frost line database)
- https://calcs.com/calculations/foundationsspreadfootingusaaci318-19
- Engineering Field Manual (USDA): Chapter 3 - Earthwork and Excavation (soil bearing capacities)
Similar Tools
Web-based platform offering 100+ pre-built structural design calculators (wood, steel, concrete, cold-formed steel) across US, Canada, Australia, New Zealand, and Eurocode standards. Features load linking between calculations, transparent code references, and calculator builder for custom solutions.
Centralized data management platform that consolidates building requirements, room data, equipment specifications, and design standards across the entire project lifecycle. Enables real-time multi-disciplinary collaboration through bi-directional integrations with Revit, ArchiCAD, IFC, and other BIM tools. Supports design validation, change management, and facility operations with 70+ built-in PDF reports and Excel exports.
Generative design platform using AI and genetic algorithms to automatically generate optimized site layouts, floor plans, and building massing solutions. Analyzes sunlight exposure, building spacing, zoning constraints, and density requirements to produce feasible design alternatives in minutes instead of days.