Structural Calculators

Check beams, lintels, LVL members, carpentry layouts, roof ventilation NFA, shelf sag, trim miters, rigging screens, deck, slab and rebar takeoffs, shafts and columns: deck joist spans by spacing/load, opening-width and wall-height searches routed to lintel size by span and load, deck beam span/post-spacing screens, load-and-soil-bearing deck footing size screens, wood spans, opening lintel load/bearing checks, rafter geometry, attic ventilation net-free-area and soffit/ridge balance, stair stringer rise/run, compound miter and crown molding angles, straight and diagonal deck board quantities, rectangular slab concrete quantity, footing concrete takeoffs, rectangular rebar spacing and weight, formula-only rebar lap-splice length screens, cut-list takeoffs, standing rigging wire safety factor, standing rigging tension and turnbuckle take-up, replacement rigging cut-length specs, wire rope stretch, area moment of inertia and section modulus S = I/c for common sections, LVL plies/depth/line loads, shaft torsion stress and angle of twist, beam load capacity, general beam deflection, solid shaft diameter from torque and bending, Euler column buckling, plus round-shaft and square-tube deflection checks.

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Common searches

I-beam moment of inertia Area moment I, section modulus and neutral axis for common sections. Beam point-load deflection Point and uniform load deflection, moment and stress for common beam cases. Euler column buckling load Critical load, effective length, slenderness and utilization. Deck joist span Simple-span joist screen from spacing, loads and entered wood values. Roof ventilation NFA Attic floor area, 1:150 or 1:300 ratio, soffit/ridge NFA and intake/exhaust balance. Opening width / wall height Routes wall-opening searches to lintel/header load checks. Lintel size by span and load Bending, shear, deflection and bearing screen for a trial member. Deck beam span Built-up beam post-spacing screen from tributary deck width. Deck ledger spacing Ledger line load and entered fastener allowable spacing screen. Deck footing size Bearing area from load and entered allowable soil bearing. Rebar lap splice length Development basis, splice factors, minimum lap and available-lap margin. Rafter length chart Common rafter length, rise, pitch angle, overhang and count. Stair stringer chart Riser count, tread count, total run, stringer length and stair angle. Concrete slab material Rectangular slab volume, cubic yards, bags, truckloads and entered-price cost. Sling angle tension Multi-leg sling angle factor, per-leg tension, required WLL and utilization. Lift point load share Two-pick center-of-gravity load split from pick-point spacing and CG offset.

Workflow suites using Structural

Multi-tool paths for jobs that cross category boundaries.

All suites

Primary Construction & Deck Layout Move field dimensions into preliminary rafter, stair, deck joist and beam, slab and footing numbers, with ventilation, fastener and material takeoffs on the way. Primary Standing Rigging Spec & Sizing Keep sailboat standing-rigging wire size, target tension, load share and turnbuckle checks consistent from spec sheet to dockside tune.

Section Modulus Area moment I, section modulus S = I/c, area and neutral axis for a rectangle, round, tube, I-beam, channel, tee or angle. Block Shear Capacity AISC 360 block shear rupture (Eq. J4-5): Rn = 0.6·Fu·Anv + Ubs·Fu·Ant capped by gross-section yield, with LRFD φRn and ASD Rn/Ω from your shear and tension areas. Tension Member Capacity AISC 360 D2 tension capacity: lesser of gross yielding Fy·Ag and net rupture Fu·Ae (Ae = An·U), in LRFD or ASD, with the governing limit named. Whitmore Section Gusset-plate Whitmore effective width b_eff = w + 2·L·tan(30°), Whitmore area and tension-yield capacity (LRFD/ASD). Compression buckling is a separate check. Shaft Diameter Required solid shaft diameter from torque, bending moment, allowable shear and safety factor. Shaft Torsion Circular-shaft torsion stress, angle of twist, polar moment J and torque capacity. Shaft Deflection Bending deflection, stress and I for a round shaft as a beam (simply supported or cantilever). Column Buckling Euler critical load, effective length, slenderness and utilization for columns or cylinder rods. Square Tube Deflection Deflection, stress and I of a square/rectangular HSS tube used as a beam. Beam Deflection General beam deflection, bending moment and stress from I and S for common point and uniform load cases. Beam Load Capacity Allowable beam load from section modulus, span and allowable bending stress. Lintel Size Preliminary lintel sizing from opening span, bearing, wall and floor/roof line loads, entered section S/I, bending, shear, deflection and bearing checks. Deck Joist Span Preliminary deck joist span from joist size, spacing, live/dead loads and entered E, Fb and Fv values. Deck Beam Span Preliminary deck beam span and post-spacing screen from built-up plies, tributary deck width, loads and entered E, Fb and Fv values. Deck Ledger Fastener Spacing Deck ledger line load and fastener spacing screen from tributary width, area loads and entered allowable per fastener. Deck Footing Size Preliminary deck or post footing bearing area, round diameter, square width, selected footing utilization and concrete quantity from load and entered allowable soil bearing. Wood Beam Span Preliminary sawn-lumber beam or joist span from 2x size, spacing, live/dead loads and entered E, Fb and Fv values. Notched Joist Capacity Elastic net-section bending, shear and notch-depth ratio screen for a notched rectangular joist or beam. Deck Board Decking board count, board rows, linear decking, fasteners and board cost from deck size and board layout. Deck Diagonal Board Diagonal deck board rows, linear decking, boards to buy, longest run and cost from deck size, angle and board layout. Deck Footing Concrete Concrete volume, bag count and concrete weight for round deck footings from diameter, depth and count. Concrete Slab Rectangular slab concrete volume, cubic yards, bags, ready-mix truckloads, weight and entered-price cost from dimensions, count and waste. Rebar Spacing Rectangular slab, wall or footing rebar layout takeoff: bar count, actual spacing, total length, stock sticks and estimated weight. Rebar Lap Splice Length Formula-only lap splice length, available-lap margin and lap allowance from entered development basis, splice factors and bar count. Wood Fence Material Wood fence posts, sections, rails, pickets, gate openings, post-hole concrete bags and material cost from a linear fence run. Rafter Common rafter length, roof rise, pitch angle, overhang tail length and rafter count for gable roof layout. Roof Ventilation Attic roof ventilation net free area, intake/exhaust split, vent count or linear feet and NFA balance from floor area and product data. Compound Miter Crown molding miter and bevel settings from corner angle and spring angle, plus flat trim/baseboard miter mode. Trim Molding Baseboard, crown, chair rail or casing linear feet, stock pieces, waste, leftover and material cost from room dimensions and openings. Stair Stringer Stair riser count, actual riser height, tread count, total run, stringer length and stair angle from total rise and tread run. Standing Rigging Wire Size Sailboat rigging wire required breaking strength, safety factor, utilization, initial tension and elastic stretch from load and wire data. Standing Rigging Tension Sailboat standing-rigging target tension, measured tension error, turnbuckle take-up, predicted tension, stretch and utilization from wire strength, span and thread pitch. Standing Rigging Spec Sailboat replacement stay or shroud cut wire length, pin-to-pin breakdown, turnbuckle setup, take-up reserve, turns and stretch allowance. Wire Rope Stretch Wire rope or standing-rigging elastic stretch, constructional stretch, total stretch, stiffness and metallic area. Sling Angle Load Multi-leg sling or bridle angle tension, angle factor, required per-leg WLL and utilization from load, loaded legs and sling angle. Rigging Center of Gravity Two-pick rigging center-of-gravity load share, left/right pick loads, sling-leg tension, WLL utilization and limiting total load. Rigging Hitch Capacity Sling capacity in vertical, choker or basket hitch — card factors (75%/200%) with basket leg-angle reduction, tag-adjustable. Outrigger Pad Size Crane pad/mat bearing area from outrigger reaction ÷ allowable ground pressure, plus the GBP check of the pad you carry. LVL Beam Preliminary LVL beam sizing from span, plies, depth, uniform line loads and product design values, with bending, shear and deflection checks.

These tools handle the questions every machine-frame, roof layout, deck takeoff, stair stringer, trim layout, beam or shaft check comes down to: what is the geometry, how stiff is the section, will it stay below allowable stress, and will a compression member buckle first. The deck joist span calculator narrows the wood-span workflow to simple-span deck joists, turning joist spacing and live/dead area loads into line load before checking bending, shear and deflection from entered E, Fb and Fv values. The deck beam span calculator moves one step down the deck load path by turning tributary deck width into beam line load and checking built-up ply post spacing from entered E, Fb and Fv values. The deck ledger fastener spacing calculator turns tributary deck width and area loads into ledger line load, then screens repeated fastener spacing from entered allowable load per fastener and a user-entered spacing cap. The deck footing size calculator then moves to the support point, turning entered post load and allowable soil bearing into required bearing area, round diameter, square width and selected-footing utilization. The wood beam span calculator screens a single sawn rectangular member from 2x size, spacing, live/dead area loads and entered E, Fb and Fv values, then compares bending, shear, live-deflection and total-deflection span limits. The lintel size calculator narrows that beam workflow to door and window openings by converting wall area load plus floor/roof line load into simple-span bending, shear, deflection and bearing checks for an entered trial section. For cabinet and furniture work, the shelf sag calculator narrows the same stiffness idea to shelf span, depth, thickness, load, material E and support condition. The rafter calculator covers common gable-roof layout from span, pitch, ridge thickness, overhang and spacing, returning run, rise, cut length, pitch angle, rafter count and stock length. The stair stringer calculator lays out riser count, actual riser height, tread count, total run, stringer length and stair angle from total rise and tread run. The compound miter calculator calculates crown molding miter and bevel settings from measured corner angle and spring angle, plus ordinary flat-trim or baseboard miter mode. The trim molding calculator estimates baseboard, crown, chair rail or casing linear feet, whole stock pieces, waste, leftover and material cost from room dimensions and openings. The deck board calculator is intentionally a material takeoff, estimating board rows, boards to buy, linear decking, screws and board cost from a rectangular layout. The deck diagonal board calculator adds angled decking row projection, longest run and waste-aware board count. The concrete slab calculator estimates rectangular slab volume, cubic yards, bags, ready-mix truckloads, concrete weight and entered-price cost from slab dimensions, count, waste and bag yield. The deck footing concrete calculator estimates round-footing concrete volume, bags and weight from diameter, depth, count, bag yield and density. The rebar spacing calculator turns entered rectangular slab, wall or footing spacing into bar counts, actual spacing, straight length, stock sticks and estimated bar weight. The rebar lap splice length calculator uses an entered development basis, project factors, minimum lap and available lap length for formula-only splice planning. The wood fence material calculator covers adjacent outdoor takeoff work: posts, rails, pickets, gate openings, post-hole concrete bags and material cost from a linear fence run. These shelf, deck, slab, rebar, fence, stair, lintel and trim tools do not size framing, footings, reinforcement, fasteners, connections, lap splices or code details; final work still needs approved span tables, adopted codes, drawings or engineering where applicable.

The section modulus calculator returns the area moment of inertia I, the section modulus S = I/c, cross-section area and neutral-axis location for a solid rectangle, round bar, round or rectangular tube, plus I-beam, channel, tee and angle sections — the same I that feeds the bending-stress equation σ = M/S. The LVL beam calculator adds the practical engineered-wood layer: plies, depth, live/dead line loads, product E/Fb/Fv values, bending, shear and L/deflection checks. The beam load capacity calculator turns section modulus, span and allowable stress into total point or uniform load, while the beam deflection calculator uses entered I and S for simply supported and cantilever loads, returning deflection, maximum moment and bending stress. The standing rigging wire size calculator compares design load, selected wire breaking strength and target safety factor, the standing rigging tension calculator turns selected wire strength, measured tension, span, stiffness and turnbuckle pitch into target tension and take-up, the standing rigging spec calculator turns measured pin-to-pin length, terminal allowance and turnbuckle travel into replacement cut length and take-up reserve, and the wire rope stretch calculator focuses on elastic and constructional stretch from F*L/(E*A). The shaft torsion calculator checks circular-shaft shear stress, angle of twist and polar moment J; the shaft diameter calculator solves solid round shaft diameter from torque, bending moment and allowable shear.

Pair those with the round-shaft deflection calculator for δ = F·L³/(48·E·I) simply supported or F·L³/(3·E·I) as a cantilever, or the square and rectangular tube deflection calculator for HSS members carrying a transverse load.

The column buckling calculator applies Euler Pcr = π²EI/(KL)² with effective length and slenderness. Every result shows the governing closed-form expression, in both metric and imperial, and the guide on what is section modulus explains the underlying geometry if S and I still feel abstract.

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