Construction & Trade Calculators for On-Site Use
Practical calculators for concrete, materials, electrical, plumbing, and common jobsite measurements.
Available Calculators
Concrete Slab Calculator
Calculates concrete volume for slabs, pads, and footings. Outputs cubic yards, bag quantities, and estimated material requirements based on entered dimensions.
Open Concrete Slab Calculator →Paint Calculator | How Much Paint Do I Need? (By Square Feet, Room Size)
Free paint calculator by square feet. Find out paint coverage per gallon (interior/exterior), how much paint for a 10x12 room, bathroom, or garage. Includes step-by-step guide.
Open Paint Calculator →Gravel Calculator | How Much Gravel Do I Need? (Tons, Cubic Yards)
Free gravel calculator: convert cubic yards to tons, calculate coverage per ton for driveways and paths. Pea gravel, crushed stone, and #57 gravel density charts included.
Open Gravel Calculator →Reference Charts
Fraction to Decimal Chart | Inch Conversion Reference
Free fraction to decimal conversion chart with printable reference tables. Convert fractions to decimals instantly with our interactive chart showing 1/64 to 1 inch in decimal and metric (mm) equivalents.
Open Interactive Chart →Lumber Size Chart | Nominal vs Actual
Lumber size chart for contractors and DIY builders. See dimensional lumber sizes (nominal vs actual), weight per foot, and cost estimates for common 2x4, 2x6, 4x4 and beam sizes in SPF and pressure-treated lumber.
Use Lumber Size Calculator →Fraction to Decimal Chart (16ths of an Inch) | Inch Conversion Table
Use this fraction to decimal chart for 16ths of an inch to convert measurements to decimal inches and millimeters. Includes a printable table and accuracy tips.
View 16ths Chart →Field Guides
How to Read a Tape Measure (Fractions, Decimals and Millimeters)
Learn how to read a tape measure in inches, fractions, decimals and millimeters. See what each line means and use charts from OnSiteCalculator for quick conversions.
Read Guide →1/16 vs 1/32 vs 1/64 Inch Accuracy | Which Precision Do You Need?
Do you need 1/16, 1/32 or 1/64 inch accuracy? Learn when each precision level is appropriate for framing, trim, cabinets and machining with OnSiteCalculator charts.
Read Guide →Paint Coverage Per Gallon (Interior, Exterior, Trim) | Coverage Rates Chart
Paint coverage per gallon: 350–400 sq ft interior walls, 250–350 exterior. Coverage rates chart by paint type, surface, coats. Free calculator included.
Read Guide →Why Use Our Calculators?
Accurate Calculations
Formulas follow standard construction measurement practices commonly used across building trades.
Material Planning Support
Supports estimating material quantities before ordering or scheduling work.
On-Site Usability
Designed for use on phones and tablets during field work and planning.