Construction Calculator Blog
Guides, trade tips, and honest takes on construction math.
Guides
Brick Calculator: How Many Bricks Per Square Foot?
Standard brick count per square foot for walls and pavers, mortar bags per 100 bricks, waste by bond pattern, and the difference between veneer and structural.
GuideFence Calculator: Posts, Rails, Pickets, and Concrete
How to calculate fence materials from linear footage. Post spacing, rail count, picket count by gap width, and concrete per post hole. Wood privacy, picket, and chain link.
GuideWatts to Amps Calculator: The Electrical Formulas You Actually Need
How to convert watts to amps, amps to watts, and calculate circuit capacity. Single-phase and three-phase, with real jobsite examples.
GuideConcrete Footing Calculator: Size and Volume
How to size and calculate concrete for footings. IRC Table R403.1, frost depth, pier vs continuous, soil bearing capacity, and Sonotube volumes.
GuideElectrical Load Calculation: NEC Article 220
How to calculate residential electrical panel load using NEC 220 standard and optional methods. General lighting, appliance circuits, HVAC, range, dryer, and service sizing.
GuideGravel Calculator: How Much Gravel Do I Need?
Cubic yard formula for gravel, tonnage conversion, depth by application, and compaction factors. Driveways, French drains, patios, and foundation base.
GuideInsulation Calculator: R-Value, Bags, and Batts
How to calculate insulation by R-value target, bags for blown-in, batts for walls, and IRC climate zone requirements. Attic, walls, and crawlspace.
GuideDrywall Calculator: How Many Sheets Do I Need?
Wall and ceiling square footage to sheet count, 4x8 vs 4x12 optimization, joint compound, tape, screws, and waste factors. The full drywall estimate.
GuideRetaining Wall Calculator: How Many Blocks Do I Need?
Block count, cap pieces, base gravel, backfill, and drainage for segmental retaining walls. Includes geogrid requirements by wall height.
GuideSlope Calculator: Grade, Percent, and Inches per Foot
How to convert between percent grade, inches per foot, and ratio for drainage, sewer pipe, concrete flatwork, and yard grading. With code requirements.
GuideHow to Calculate Tile for a Floor
Square footage to tile count, waste factors by layout pattern, thinset coverage, and backer board math. Real tile estimation, not guesswork.
GuideHow Much Paint Do I Need for a Room?
Wall area formula, coverage rates per gallon, trim and ceiling math, and when one coat won't cut it. The full paint calculation.
GuideHVAC Duct Sizing: CFM to Duct Size
How to size ducts from CFM, the friction rate method, rectangular-to-round equivalents, and common residential branch sizes. With the actual tables.
GuideMulch Calculator: How Many Cubic Yards Do I Need?
Cubic yard formula for mulch and topsoil, coverage per yard at different depths, bulk vs bag pricing, and how much a pickup truck actually holds.
GuideBoard Feet Calculator: How to Calculate Lumber
Board feet calculator formula with worked examples, a reference table for common lumber sizes, and when board feet matter vs linear feet.
GuideDeck Calculator: Boards, Joists, Beams, and Footings
Calculate decking boards, joists, beams, and footings for any deck. Full material list for a 12x16 example with 5/4 vs 2x6 and spacing options.
GuideHow to Calculate Concrete for a Slab
Step-by-step concrete slab calculation with the cubic yard formula, waste factors, and when bags beat ready-mix. Real math, no fluff.
GuideStair Calculator: Rise, Run, and Stringer Layout
Stair calculator math for rise, run, and stringer layout. IRC R311.7 code limits, Pythagorean stringer length, and the mistakes that fail inspections.
GuideVoltage Drop Calculator: The NEC Formula and How to Use It
Voltage drop calculator formula from the NEC with worked examples, wire gauge data, and correction factors for single-phase and three-phase circuits.
GuideStud Count Calculator: How Many Studs Do I Need?
Calculate wall studs for any layout. Spacing formula, corners, king and jack studs for openings, plates, and blocking. The full count.
GuideHow to Calculate Roof Area from Pitch
Pitch multiplier table, footprint-to-actual-area formula, and how to figure squares for roofing. Every roofer needs this math.
GuideRebar Calculator: How Much Rebar for a Slab
Calculate rebar quantity for concrete slabs. Spacing in both directions, bar weight, lap splice lengths, and ACI 318 references.
GuideVoice Input for Construction Calculators
How SiteCalc's voice input parses spoken dimensions, strips filler words, and handles fractions. Why it matters on a job site.
Comparisons
SiteCalc vs Construction Master Pro Comparison
Side-by-side comparison of SiteCalc and Construction Master Pro calculator apps. Pricing, features, calculator count, and what each does better.
ComparisonConstruction Calculators Without Subscriptions
Why subscription pricing for construction calculator apps is wrong, and what the backlash against Construction Master Pro's model means.
Trade Articles
Conduit Fill Calculator: NEC Chapter 9 Tables Explained
How to calculate conduit fill using NEC Chapter 9 Tables 1, 4, and 5. Fill percentages, usable area by conduit type, and a worked example.
TradeHow to Size Wire for a Circuit
NEC 310.16 ampacity table explained, voltage drop formula, and when to upsize wire. Practical guide for electricians and DIYers.
TradeHow to Size a Header (IRC Table R602.7)
IRC header sizing for residential construction. Full R602.7 table explained, load conditions, snow load, and why your 2x6 might fail.
TradeDrain Pipe Sizing with DFU Tables (IPC 710.1)
How to size drain pipes using DFU values from IPC Table 709.1 and pipe sizing from IPC 710.1. Slope requirements and fixture counts.