Construction & Electrical Calculators

Formula-based calculators for concrete, grading, framing, roofing, and HVAC, plus electrical load, cable, generator, and transformer sizing.

The most-used tools for concrete, slope, drainage, sitework, and framing, plus key electrical sizing checks.

Concrete CalculatorConcrete & MasonryEstimate concrete yards and bags for slabs and footings.Cubic Yard CalculatorMeasurement & ConversionFind cubic yards from length, width, and depth.Pea Gravel CalculatorGravel, Sand & StoneEstimate pea gravel in yards, tons, and bags for an area.Percent Slope CalculatorSlope & GradeFind percent slope from rise and run, with angle and ratio.Pipe Slope CalculatorPlumbing & DrainageFind pipe slope, grade, and drop from run and fall.Road Base CalculatorGravel, Sand & StoneEstimate road base tons and truckloads for compacted depth.French Drain CalculatorPlumbing & DrainageEstimate gravel, pipe, and fabric for a French drain.Beam Deflection CalculatorStructural LoadsFind beam deflection, moment, and shear under load.Wood Fence CalculatorDeck, Fence & OutdoorEstimate pickets, posts, rails, and cost for a wood fence.

Explore Construction Calculator Clusters

Concrete & Masonry

28 calculators

Yards, bags, blocks, bricks, rebar, mortar, and grout for slabs, footings, and walls.

See all Concrete & Masonry calculators

Gravel, Sand & Stone

17 calculators

Tons and cubic yards of gravel, base rock, sand, rip rap, loam, and mulch.

See all Gravel, Sand & Stone calculators

Paving & Sitework

12 calculators

Cut and fill, excavation slopes, asphalt tons, and driveway costs.

See all Paving & Sitework calculators

Slope & Grade

10 calculators

Percent, ratio, and degree slopes, ramps, elevations, and square layouts.

See all Slope & Grade calculators

Plumbing & Drainage

28 calculators

Pipe fall, flow, head loss, runoff, and tank, pool, and pond volume.

See all Plumbing & Drainage calculators

Structural Loads

5 calculators

Beam reactions, bending stress, deflection, and soil bearing pressure.

See all Structural Loads calculators

Deck, Fence & Outdoor

25 calculators

Deck boards, balusters, fence posts, sheds, coops, and lawns.

See all Deck, Fence & Outdoor calculators

Stairs, Angles & Curves

10 calculators

Risers, treads, spiral stairs, miter cuts, arches, and ladder angles.

See all Stairs, Angles & Curves calculators

Fasteners & Fabrication

24 calculators

Bolt torque, threads, spindle speed, bend allowance, and welds.

See all Fasteners & Fabrication calculators

Measurement & Conversion

8 calculators

Square feet, square yards, cubic yards, cost per foot, and FAR.

See all Measurement & Conversion calculators

Flooring, Walls & Finishes

25 calculators

Tile, flooring boxes, drywall, paint, siding, trim, and install cost.

See all Flooring, Walls & Finishes calculators

Roofing & Roof Framing

22 calculators

Pitch, rafters, trusses, roof squares, snow load, and chimneys.

See all Roofing & Roof Framing calculators

Lumber & Framing

10 calculators

Board feet, studs, plywood, joist spans, headers, and wood weight.

See all Lumber & Framing calculators

Material Weight

7 calculators

Weight of steel plate, bar, beams, pipe, aluminum, and glass.

See all Material Weight calculators

HVAC & Airflow

16 calculators

AC tons, BTUs, heat loss, CFM, duct sizing, and R-value.

See all HVAC & Airflow calculators

Explore Electrical Calculator Clusters

Wiring & Installation

11 calculators

Wire size, ampacity, voltage drop, box fill, and conduit bends.

See all Wiring & Installation calculators

Power, Energy & Batteries

13 calculators

Ohm's law, watts, kWh cost, RMS voltage, and battery runtime.

See all Power, Energy & Batteries calculators

Motors, Generators & Transformers

8 calculators

Full-load amps, speed, torque, kVA, and fault current.

See all Motors, Generators & Transformers calculators

Resistors, Capacitors & Inductors

13 calculators

Color codes, parallel networks, reactance, and time constants.

See all Resistors, Capacitors & Inductors calculators

Amplifiers, Timers & Filters

6 calculators

Op-amp gain, hysteresis, 555 timing, and bandpass design.

See all Amplifiers, Timers & Filters calculators

PCB & Transmission Lines

13 calculators

Microstrip and stripline impedance, trace width, and crosstalk.

See all PCB & Transmission Lines calculators

RF Links & Antennas

9 calculators

EIRP, path loss, link margin, noise figure, and patch antennas.

See all RF Links & Antennas calculators

RF Components & Matching

11 calculators

VSWR, attenuator pads, matching, dividers, and waveguide.

See all RF Components & Matching calculators

Waves, Fields & Optics

7 calculators

Wavelength, decibels, skin depth, refraction, and beam power.

See all Waves, Fields & Optics calculators

Latest Construction & Electrical Calculators

New construction and electrical tools are added regularly, from sitework and drainage to power, generators, and transformers.

Bentonite CalculatorPlumbing & DrainageBentonite Calculator that finds a pond's real sloped area, applies soil rates from three published charts...Voltage Rise CalculatorWiring & InstallationVoltage Rise Calculator for solar inverter AC cables. It adds the rise in each cable back...Concrete Mix CalculatorConcrete & MasonrySplit concrete volume into cement, sand, gravel, water.Three-Phase Power CalculatorPower, Energy & BatteriesThree-Phase Power Calculator finds real, reactive and apparent power from line volts, current and its power...Battery Size CalculatorPower, Energy & BatteriesBattery Size Calculator finds the amp-hours a battery needs to run a load for a set...Generator Fault Current CalculatorMotors, Generators & TransformersCalculate a generator's subtransient, peak, and sustained fault currents, from power, voltage, and impedance to verify...Generator Current CalculatorMotors, Generators & TransformersGenerator Current Calculator finds full load current from a set's kVA or kW rating, then lists...Transformer Fault Current CalculatorMotors, Generators & TransformersCalculate three-phase, line-to-line, and line-to-ground short-circuit current at a transformer's secondary terminals from kVA, voltage, and...Transformer CalculatorMotors, Generators & TransformersTransformer Calculator turns rated kVA and line voltage into primary and secondary amps, the turns ratio,...

What Makes CalcFormula Different

Our Construction & Electrical Calculators use real formulas, cite the codes behind them, and give results in the units suppliers sell.

330+ Tools, Two Trades

Construction calculators in 15 categories, from concrete to HVAC, plus a full set of electrical tools.

The Formula Is on the Page

Each result comes with the formula and a worked example, so you can check the number by hand.

Backed by Codes and Standards

Category guides cite the IRC, OSHA, ADA, ACCA, and ASME rules behind the numbers you enter.

Results You Can Order

Quantities come out in bags, boxes, sheets, and tons, with waste you can adjust for your job.

Free, Fast, Mobile

No account or paywall. Every tool runs in your browser and works on a phone at the jobsite.

Honest About Limits

Results are for planning and ordering. Structural, trench, and permit work still needs a professional check.

Frequently Asked Questions

Common questions about CalcFormula's construction and electrical calculators.

What does CalcFormula cover?

CalcFormula has two libraries of Construction & Electrical Calculators. The construction library is split into 15 categories, running from concrete, gravel, and grading through framing, roofing, finishes, and HVAC. The electrical library covers load, power, cable, generator, and transformer calculations. Use the menu or the category cards above to jump straight to the trade you need.

Are the calculators free, and do I need an account?

Every calculator is free, with no account, login, or paywall. The math runs in your browser, so results appear as soon as you change an input. That also makes the tools practical on a phone at the jobsite, where you can test a few layouts before calling a supplier.

Where do the formulas come from?

Formulas come from published codes, standards, and manufacturer data. The category guides reference sources such as the IRC for stairs, joists, and footings, OSHA for trench slopes, the ADA for ramps, ACCA for HVAC loads, and ASME for pipe weight. Bag yields and coverage rates come from product data sheets. Tool pages show the formula, so you can check any result by hand.

How accurate are the results?

The math is exact for the numbers you enter, so accuracy depends on those inputs. Material weight is the biggest variable. Gravel, for example, runs from about 1.2 to 1.7 tons per cubic yard, so a 10-yard order could be anywhere from 12 to 17 tons. Enter your supplier's density, bag yield, or coverage figure, and the result will line up closely with their quote.

How do I find the right calculator quickly?

Type the material or task into the search bar, such as "rebar," "roof pitch," or "voltage rise." If you are not sure of the name, open the category that matches your project stage. Each category page lists every tool in it, with a short line on what each one works out.

Can I use the electrical calculators to size wire or breakers?

Use them to plan and to check your own numbers. Final conductor, breaker, and protection sizes must follow the National Electrical Code edition your state has adopted, plus any local amendments. Code tables also apply corrections for temperature, conduit fill, and conductor type that a quick estimate may not cover. Have the design confirmed by a licensed electrician or your inspector.

Found an error or need a calculator that doesn't exist yet?

Use the Report a Bug page. For an error, include the tool's page link, the inputs you entered, and the result you expected, so the math can be traced quickly. For a new tool, describe the job it should handle and the numbers you would enter.