Work out how much
before you buy it.

Concrete, lumber, wire, filament — work out how much you need before you buy it. Put the numbers in and you get the quantity, the waste allowance and the working behind it, in a form you can copy into an order.

Concrete & Masonry

Concrete Slab Calculator — Bags and Cubic Yards for a Slab, Footing or PierCubic yards and bag count for a slab, footing or pad Brick and Block Calculator — How Many Bricks or CMU per Square Foot of WallUnit count, mortar and sand for a brick or CMU wall Mortar Mix Calculator — Bags of Type N, S or M for Laying and RepointingMortar volume for laying or repointing, as bags or as portland, lime and sand Retaining Wall Block Calculator — Courses, Caps, Base Gravel and Drain StoneBlock count, courses, caps and gravel for a segmental retaining wall Paver Patio Calculator — Pavers, Base Gravel and Joint Sand by PatternPaver count, base gravel, bedding sand and joint sand for a patio or walkway

Lumber & Framing

Wood Movement Calculator — Seasonal Width Change and the Gap a Joint NeedsSeasonal width change by species and grain, and the slot or gap to allow for it Wood Finish Coverage Calculator — How Much Stain, Oil, Poly or Shellac to BuyQuantity of stain, oil, polyurethane or shellac for an area and a number of coats Glue and Clamp Calculator — Glue Quantity, Clamp Count, Spacing and PressureGlue quantity for a glue-up, plus how many clamps, how far apart and how hard Shelf Sag Calculator — Deflection by Span, Thickness, Material and LoadPredicted deflection of a shelf, and whether it clears an acceptable-sag limit Board Foot Calculator — Nominal vs Actual, Quarter Sizes and Lumber CostBoard feet and cost for dimensional lumber and rough hardwood Stud Wall Framing Calculator — Studs at 16 or 24 On Center, Plates and HeadersStuds, plates, headers and board feet for a framed wall Deck Board Calculator — Boards, Linear Feet, Joists and FastenersDeck boards, lineal feet, fasteners and joist count for a deck surface Plywood Sheet Calculator — How Many 4x8 Sheets and How Much OffcutSheets of plywood, OSB or MDF for a given area, with offcut left over

Paint, Tile & Flooring

Curtain Size Calculator — Panel Width, Length and Fabric Yardage With FullnessFinished panel width and length, panel count and yardage Drywall Sheet Calculator — Sheets, Screws, Tape and Joint Compound for a RoomSheets, screws, tape and mud for walls and ceiling Insulation Calculator — Batts or Blown Bags for a Target R-ValueBatt count or bags of blown, and the depth an R-value needs Lighting Layout Calculator — Recessed Light Spacing, Count and Lumens per RoomLumens for the room, fixture count and the spacing grid Roofing Squares Calculator — Shingle Bundles, Starter, Ridge Cap and NailsSquares, bundles, starter, ridge cap and nails for a shingle roof Roof Pitch Calculator — X-in-12 to Degrees, Percent and the Slope MultiplierConvert pitch to degrees, percent and the area multiplier Gutter and Downspout Sizing Calculator — 5 in or 6 in K-Style and How Many LeadersGutter size, downspout count and spacing from roof area and rainfall Roof Underlayment and Drip Edge Calculator — Rolls, Sticks and Ice BarrierUnderlayment rolls, drip edge sticks and ice barrier coverage

Electrical

Voltage Drop Calculator — Percent Drop Over a Run in Copper or AluminumVolts and percent lost over a run, for copper or aluminium Wire Size Calculator — AWG for a Given Load, Distance and Voltage Drop TargetConductor size a run needs to hold a target voltage drop Circuit Load Calculator — Amps on a Branch Circuit and the 80 Percent RuleAdd up the loads on a branch circuit against the breaker rating Generator Sizing Calculator — Running Watts vs Starting Surge by ApplianceRunning watts and starting surge for a list of appliances

Plumbing & Water

Pipe Volume Calculator — Gallons of Water in a Run of Copper, PEX or PVCGallons, weight and flush time for a length of pipe Water Flow Pressure Drop Calculator — Friction Loss and Velocity in a Pipe RunFriction loss in psi and velocity in ft/s over a run Pool Volume Calculator — Gallons in a Rectangular, Round or Oval Pool or TankGallons and turnover time for a pool, pond or tank Drain Slope Calculator — Fall Per Foot for a Waste Line or French DrainTotal fall and invert elevations for a sloped drain run

Yard & Garden

Sod and Grass Seed Calculator — Rolls, Pallets and Pounds of Seed by Lawn SizeSod rolls, pallets and pounds of seed for a lawn area Fertilizer Calculator — Pounds of Product From an N-P-K Analysis and a Nitrogen TargetPounds of product from the bag analysis and a lb-N target Firewood Cord Calculator — Cords, Face Cords, Price per Cord and Heat ValueCords and face cords from stack size, with price and heat value Irrigation Zone Calculator — Heads per Zone, Zone Count and Sprinkler Run TimeHeads per zone, zone count and run time from GPM and head spacing Mulch Calculator — Cubic Yards and 2 Cu Ft Bags by Bed Size and DepthCubic yards, bag count and bulk order for beds Topsoil Calculator — Cubic Yards, Bags and Tons With a Settling AllowanceCubic yards, bags and approximate tons of soil or garden mix Gravel Driveway Calculator — Yards and Tons per Layer With CompactionCubic yards and tons of gravel by layer, with compaction Fence Post Calculator — Post Count, Spacing and Concrete per HolePost count, rails or panels, and concrete per hole

3D Printing

Filament Cost Calculator — Cost per 3D Print Including Power and FailuresWhat a 3D print actually costs — filament, power, wear and failures Resin Print Cost Calculator — Cost per Part Including IPA, FEP and FailuresCost per part for MSLA resin printing, including IPA, FEP and failures

Shop Math

CFM Calculator from Air Changes per Hour — Fan Sizing for a Bathroom, Kitchen or ShopRequired CFM from room volume and a target ACH, and the reverse Duct Size Calculator — Round and Rectangular Duct from CFM, Velocity or Friction RateRound diameter and equivalent rectangular sizes from CFM Dust Collection Calculator — CFM Per Machine, Duct Velocity and Whether Your Collector Is EnoughRequired CFM, transport velocity check and system resistance Dehumidifier Size Calculator — Pints Per Day for a Basement, Crawlspace or ShopPints per day from area, dampness level and conditions Cut List Optimizer — How Many Boards or Bars, With Kerf and OffcutFit a list of parts onto stock lengths with the kerf accounted for Miter Angle Calculator — Compound Miter and Bevel for Any Number of SidesMiter and bevel settings for corners, polygons and compound sloped work Appliance Running Cost Calculator — What a Device Costs per Day, Month and YearCost per day, month and year from watts and hours LED Conversion Savings Calculator — Annual Savings, Payback and Lifetime CostAnnual savings, payback and lifetime cost of switching to LED

Metal & Welding

Metal Weight Calculator — Steel, Stainless, Aluminum and Brass Bar, Tube, Plate and AngleWeight of plate, bar, tube and angle in steel, stainless, aluminum, brass or copper Bend Allowance Calculator — Flat Pattern, Bend Deduction and K-Factor for Sheet MetalFlat blank length from thickness, bend radius, angle and K-factor Tap Drill Size Calculator — Tap and Clearance Drills for UNC, UNF and Metric ThreadsTap drill and clearance drill for any common thread, at the engagement you choose Weld Cost Calculator — Deposited Metal, Filler, Gas and Labor per JointDeposited weld metal, filler consumed, gas used and cost per joint

Vehicle & Garage

Tire Size Comparison Calculator — Diameter, Circumference and Speedometer ErrorCompare two tire sizes and the speedometer error between them Gear Ratio Speed Calculator — MPH from RPM, Axle Ratio and Tire DiameterRoad speed and cruising rpm from gearing and tire size Towing and Payload Calculator — What Is Left After Passengers, Cargo and Tongue WeightPayload left over once passengers, cargo and tongue weight are counted Oil Change Cost Calculator — Cost per Change, per Year and per MileCost per oil change, per year and per mile, comparing two options

Solar & Off-Grid

Solar Panel Array Sizing Calculator — Array kW, Panel Count and Roof Area for a Daily LoadArray kW and panel count for a daily kWh load Battery Bank Sizing Calculator — Amp-Hours, Usable kWh and Series/Parallel LayoutAmp-hours and battery count for a backup or off-grid bank Inverter and Charge Controller Sizing Calculator — Continuous Watts, Surge and MPPT vs PWM AmpsInverter continuous and surge watts, plus controller amps Solar Payback Calculator — Years to Break Even and 25-Year Savings on a Solar SystemBreak-even years and lifetime savings on a solar system

What this is

Most material questions have a clean answer that nobody writes down plainly. How many bags of concrete for a four-inch slab. Whether 14 gauge is enough over a forty-foot run. How much filament a print actually eats. The calculators here give the number and show the arithmetic, including the assumption that is most likely to be wrong for your job, so you can change it rather than guess again.

Nothing is uploaded. Everything runs in your browser, there is no sign-up, and each page states the range its figures vary over instead of quoting a false precision.