Engineering Tools
Field-ready calculators for engineers: HVAC loads, flows, pressures, materials and more—reliable results, instant outputs.
Audio Tools 1
Loudness Meter
Measure integrated, short-term and momentary LUFS plus true-peak and LRA per EBU R128 / ITU-R BS.1770. Free in-browser loudness meter for podcasts and music.
Calculators 58
Engineering Calculators 42
Cross-Section Properties
Free cross-section calculator: area, centroid, moment of inertia (Ix, Iy), section modulus, radius of gyration & plastic modulus for I-beams, pipes & polygons.
Beam Analysis
Free beam calculator: reactions, shear force & bending moment diagrams, and deflection for simply supported, cantilever & overhanging beams under any loads.
Steel Section Database
Free IPE steel beam properties table (EN 10365): dimensions, area, moment of inertia, section modulus, radius of gyration and mass. Filter by depth and find the lightest section.
Resistor Color Code
Decode 4, 5, 6 band resistor colors to ohm value and tolerance, reverse-lookup E12/E24/E48/E96 parts, and check power rating, max current and voltage.
ADA ramp calculator
Wheelchair ramp calculator for 2010 ADA Standards & IBC/A117.1: slope percent, length, landings, handrail length, and 1:8/1:10 alteration compliance.
Area calculator
Area & square footage calculator for rectangle, circle, triangle and more. Add a waste factor and unit price to estimate material quantity and total cost.
Asphalt calculator
Asphalt calculator for driveways, roads and parking lots: estimate hot mix tonnage, cubic yards, metric tonnes, aggregate base and total cost by area and thickness.
BTU calculator
Free air conditioner size calculator: find how many BTU you need by room size, then convert BTU to tons & kW with cooling/heating modes.
Beam load calculator
Compute maximum deflection, bending moment and shear force for simply supported and cantilever beams under point or distributed loads. Free for engineers.
Blueprint measurer
Blueprint measurement tool — upload architectural drawings, calibrate with a known dimension, then measure any distance on floor plans and elevations.
Brick calculator
Free brick calculator: bricks per m2, mortar bags and waste for any wall. Deducts door and window openings for an accurate brickwork estimate.
CFM calculator
ASHRAE 62.1 CFM calculator for HVAC fan & duct sizing. Compute air flow from room size, air changes, or BTU load with altitude density correction & L/s output.
Concrete calculator
Concrete calculator for slabs, columns, footings, curb and stairs. Get cubic yards, m3, 60/80 lb bag counts and the M20 mix ratio take-off.
Drywall calculator
Drywall calculator: estimate 4x8/4x10/4x12 sheets, sheet weight, screws, tape and compound for walls and ceilings, with 5/8" Type X fire-rated guidance.
Duct & pipe pressure calculator
ASHRAE Darcy-Weisbach pressure drop calculator for HVAC ducts and water pipes. Friction and fitting K-factor losses, equivalent diameter, velocity check.
Duct size calculator
Duct size calculator for HVAC: get round or rectangular dimensions, equivalent round diameter, friction loss per 100 ft, and an ASHRAE velocity check.
FAR & lot coverage calculator
Calculate Floor Area Ratio (FAR/FSI/FSR), chargeable buildable area, lot coverage and minimum open space for zoning compliance. For architects and planners.
Flow rate calculator
Flow rate and pipe sizing calculator for volumetric flow, velocity and pipe area. Convert m³/h, L/min, GPM, CFM and check velocity against code limits.
Gear ratio calculator
Free gear ratio calculator: output RPM, torque multiplication, compound trains, plus AGMA service factor and gearbox sizing for motor reduction drives.
Grade calculator
Grade calculator with slope ratio (V:H) and code-compliance pass/fail. Compute grade percent, angle and ratio against ADA, AASHTO and drainage limits.
Gravel calculator
Free gravel calculator: find how much gravel you need for a driveway or path in cubic yards, tons and bags, plus the total cost with a waste/compaction margin.
Insulation calculator
Estimate insulation needed for walls, attics and ceilings. Calculate area, R-value, thickness and ballpark material cost for fiberglass, foam or cellulose.
Material weight calculator
Material weight calculator for steel, aluminum, copper and metal. Get total weight plus weight per meter and per foot for plates, bars, tubes and pipe.
Mulch calculator
Mulch calculator for landscaping: volume for rectangular, circular and triangular beds in yd³, ft³, m³, plus bags-vs-bulk cost and waste overage.
Occupant load calculator
Calculate occupant load and IBC 2021 egress: occupancy load factor, exits, stairway width, travel distance. Verify your design and Certificate of Occupancy.
Paint calculator
Paint calculator with spread rate, two coats and textured-surface presets. Estimate liters & gallons and the real quantity to order, not just sq ft per gallon.
Parking calculator
Parking ratio calculator: required spaces by building type, editable ITE/zoning ratio, ADA & van accessible spaces, and parking lot area estimator.
Pipe volume calculator
Pipe volume calculator: internal volume from inner diameter and length in liters/gallons, plus pipe weight per meter (empty + water-filled) for steel, PVC, copper.
Pressure drop calculator
Pressure drop calculator for pipes and ducts. Compute pressure loss for water, air and gas with Darcy-Weisbach — for HVAC, plumbing and fluid mechanics.
Psychrometric calculator
Compute dew point, wet bulb, humidity ratio, enthalpy and specific volume of moist air with altitude correction, plus an ASHRAE 55 comfort check.
Pulley & belt calculator
Calculate pulley speed ratio, output RPM, belt length, wrap angle and belt speed for V-belt and flat-belt drives, with a 120-degree wrap check.
Rebar calculator
Calculate rebar quantity, length and weight for concrete slabs, then verify the steel-to-concrete ratio (kg/m³) against ACI/EC2 benchmark ranges. Free.
Refrigerant charge calculator
Estimate HVAC/AC refrigerant charge by capacity, line set length and pipe diameter, with A2L charge-limit check. R-410A, R-32, R-454B, R-22, R-134a, R-404A.
Refrigeration capacity calculator
Size walk-in cold rooms and freezers fast: get the heat load in BTU/hr, tons and kW with full transmission, product, latent and infiltration breakdown.
Roofing calculator
Roofing calculator: estimate roof area by pitch or angle, shingle bundles, metal panels, underlayment, ridge cap and drip edge for a pro takeoff.
Scale converter
Free scale converter for drawings, models and maps. Convert metric, imperial (1:48) and ISO 5455 engineering scales, plus check A1/A3 paper fit.
Slope calculator
Slope calculator for rise over run: percent grade, angle in degrees, ratio and length. Checks ADA ramp, roof pitch X:12, driveway and pipe-fall code limits.
Square footage calculator
Square footage calculator for flooring, tile, paint and drywall. Get area in m², ft², yd², in², cm², plus waste factor, units needed and total cost.
Stair calculator
Stair calculator with IRC/IBC code pass-fail checks. Get riser count, rise, run, stringer length, pitch angle and headroom compliance for safe stair design.
Tile calculator
Tile calculator for floors and walls: estimate tiles, full boxes, thinset adhesive bags, grout bags and cost by square footage or room size, with waste.
Torque calculator
Torque calculator with bolt torque mode: reverse-solve force or lever arm, and get bolt clamp load (preload) from T = K × D × F. N·m, lb·ft, kN.
Volume calculator
Volume calculator for sphere, cone, cube, cylinder, tank, capsule, pyramid and ellipsoid. Converts m³/L/gal/ft³ and shows fill weight by density.
Health & Fitness 1
Feels Like Temperature
Calculate feels-like temperature with wind chill, heat index, dew point, WBGT wet bulb globe temperature and OSHA/ACGIH heat-stress work-rest guidance.
HVAC Calculators 6
HDD & CDD Calculator
HDD & CDD calculator with base 65F/18C, 1991-2020 climate normals, IECC zone, plus building energy & fuel-cost estimate for ASHRAE 90.1 work.
U-value & R-value Converter
Convert U-value (thermal transmittance) and R-value, build multi-layer wall assemblies, add air films, and check IECC climate-zone code compliance.
Ventilation Calculator
Calculate ASHRAE 62.1 outdoor air from Rp and Ra in CFM and L/s, then run a pass/fail check on your design or measured airflow versus the minimum OA.
ACH Calculator
ACH calculator with ASHRAE 62.2 minimum, CFM to ACH conversion, clearance time and annual energy cost for HVAC, cleanroom and isolation design.
Dew Point & RH Calculator
Convert temperature, RH & dew point via Magnus-Tetens. Get wet bulb, humidity ratio, absolute humidity & vapor pressure for HVAC condensation, ASHRAE comfort.
HVAC load calculator
Free HVAC load & BTU calculator: size AC tonnage with Manual J sensible/latent split, solar gain and an ACCA Manual S oversizing compliance check.
Math Calculators 2
Complex number calculator
Add, multiply, divide complex numbers and combine parallel impedances. Rectangular to polar conversion, phasors, De Moivre powers and roots with R + jX steps.
Derivative & integral calculator
Differentiate or integrate a function symbolically, then evaluate the result at a point or compute a definite integral over [a, b]. Free, instant, no sign-up.
Wire Calculators 7
AWG to mm converter
Convert AWG wire gauge to mm and mm2 cross-section, with kcmil, nearest IEC 60228 size, NEC ampacity and copper resistance for wire sizing.
SWG to mm converter
Convert SWG (Standard Wire Gauge) to millimeters instantly. Calculate diameter and cross-sectional area with the British wire gauge converter.
Three-phase voltage drop
Three-phase voltage drop calculator with operating-temperature correction and a NEC 3%/5% or IEC pass/fail check for Delta and Wye feeders, copper or aluminum.
Voltage drop calculator
Voltage drop calculator with NEC 3%/5% and IEC pass/fail check. Get the minimum compliant AWG for DC, single- and three-phase runs in copper or aluminum.
Wire ampacity estimator
Estimate wire ampacity with derating factors for temperature and conduit fill. Reference tool based on NEC guidelines. Always consult local electrical codes.
Wire gauge calculator
Free AWG wire gauge calculator: diameter, cross-section area, resistance, plus built-in NEC ampacity and 3% voltage-drop check for copper and aluminum.
Wire resistance calculator
Wire resistance & voltage drop calculator with NEC 3%/5% check. AWG/mm/inch, °C/°F, 6 metals, temperature compensation and I²R power loss.
Conversion 37
Area Conversion 4
acre to ping
Convert acres to ping (坪) instantly. 1 acre = 1224.17 ping using the Taiwan/Japan land unit (1 ping ≈ 3.306 m²). Free acre→ping calculator for real-estate use.
ha to ping
Convert hectares to ping (坪) instantly. 1 ha = 3024.99 ping using the Taiwan/Japan unit. Free ha→坪 calculator for metric-to-East-Asia land area conversion.
ping to acre
Convert ping (坪) to acres instantly. 1 ping = 0.000817 acre (1224.17 ping = 1 acre). Free 坪→acre calculator for Taiwan/Japan land deals in US/UK measure.
ping to ha
Convert ping (坪) to hectares instantly. 1 ping = 0.0003306 ha (3025 ping = 1 ha). Free 坪→ha calculator for converting East Asian land units to metric hectares.
Electric Charge Conversion 1
All Charge Units
Convert electric charge units instantly. Coulombs, milliCoulombs, microCoulombs, nanoCoulombs, picoCoulombs, Amp-hours, milliamp-hours.
Energy Conversion 6
BTU to J
Convert BTU to Joules (BTU to J) instantly with our free online converter. Accurate 1 BTU = 1055.06 J formula, examples, conversion table and step-by-step...
BTU to kJ
Convert BTU to Kilojoules (BTU to kJ) instantly with our free online converter. Accurate 1 BTU = 1.05506 kJ formula, examples, conversion table and...
Joules to BTU
Convert Joules to BTU (J to BTU) instantly with our free online converter. Accurate 1 J = 0.000947817 BTU formula, examples, conversion table and...
Joules to cal
Convert Joules to Calories (J to cal) instantly with our free online converter. Accurate 1 J = 0.239006 cal formula, examples, conversion table and...
cal to J
Convert Calories to Joules (cal to J) instantly with our free online converter. Accurate 1 cal = 4.184 J formula, examples, conversion table and...
kJ to BTU
Convert Kilojoules to BTU (kJ to BTU) instantly with our free online converter. Accurate 1 kJ = 0.947817 BTU formula, examples, conversion table and...
Flow Rate Conversion 1
All Flow Rate Units
Convert all flow rate units instantly. Liters per second, minute, hour, cubic meters, gallons per minute, cubic feet in one tool.
Frequency Conversion 3
Hz to MHz
Convert hertz to megahertz (Hz to MHz) with SI-exact 10^-6 factor. Free converter for RF, broadcasting, and CPU clocks with BIPM-precision arithmetic.
MHz to Hz
Convert megahertz to hertz (MHz to Hz) using exact SI factor 10^6. RF, SDR and DSP-grade converter with formulas, tips and atomic-clock-traceable precision.
kHz to Hz
Convert kilohertz to hertz (kHz to Hz) with SI-exact 10^3 factor. Free audio, radio and RF converter with BIPM-compliant precision and edge-case handling.
Fuel Consumption Conversion 4
L/100km to L/100mi
Convert litres per 100 km to litres per 100 miles instantly. 1 L/100km = 1.609344 L/100mi because 100 miles is 160.9344 km — the linear km-to-mile ratio.
L/100km to MPG (US)
Convert litres per 100 km to US miles per gallon instantly. MPG = 235.215 / L100km — the inverse relationship between metric and US fuel-economy units.
MPG (UK) to MPG (US)
Convert miles per gallon UK to miles per gallon US instantly. 1 MPG UK = 0.83267 MPG US because the imperial gallon is larger than the US gallon (4.546 vs 3.785 L).
MPG (US) to MPG (UK)
Convert miles per gallon US to miles per gallon UK instantly. 1 MPG US = 1.20095 MPG UK because the imperial gallon is 20% larger than the US gallon (4.546 vs 3.785 L).
Power Conversion 6
All Power Units
Convert all power units instantly. Watts, kilowatts, megawatts, horsepower, BTU per hour, foot-pounds per second in one tool.
btu/hr to watts
Convert BTU per hour to watts instantly: 1 BTU/hr = 0.29307107 W. Free BTU/hr to W calculator for HVAC sizing, AC capacity and heating load specs.
dBm to Watts
Convert dBm to watts using the logarithmic formula P(W) = 10^((dBm-30)/10). RF / microwave converter with link-budget tips, ITU-R and IEEE references.
hp to kW
Convert horsepower to kilowatts using mechanical hp (745.6999 W). Auto, marine and industrial converter with PS / SAE / DIN definitions and worked examples.
kw to mw
Convert Kilowatts to Megawatts (kW to MW) instantly with our free online converter. Accurate 1 MW = 1000 kW formula, examples, conversion table and...
watts to btu/hr
Convert watts to BTU per hour instantly: 1 W = 3.41214 BTU/hr. Free W to BTU/hr calculator for HVAC sizing, heat-pump rating and US-spec equipment matching.
Pressure Conversion 1
mmHg to Torr
Convert millimetres of mercury to torr. 1 mmHg = 1 Torr by historical definition (both ≈ 133.322 Pa). Free mmHg→Torr calculator for vacuum, medical and meteorology use.
Temperature Conversion 10
celsius to kelvin
Convert Celsius to Kelvin (°C to K) instantly with our free online converter. Accurate K = °C + 273.15 formula, examples, conversion table and step-by-step...
celsius to rankine
Convert Celsius to Rankine (°C to °R) instantly with our free online converter. Accurate °R = (°C + 273.15) × 9/5 formula, examples, conversion table and...
fahrenheit to kelvin
Convert Fahrenheit to Kelvin instantly: K = (°F − 32) × 5/9 + 273.15. Free °F to K calculator with absolute-zero awareness and decimal precision.
fahrenheit to rankine
Convert Fahrenheit to Rankine instantly: °R = °F + 459.67. Free °F to °R calculator using the Rankine absolute scale common in US engineering thermodynamics.
kelvin to celsius
Convert Kelvin to Celsius (K to °C) instantly with our free online converter. Accurate °C = K − 273.15 formula, examples, conversion table and step-by-step...
kelvin to fahrenheit
Convert Kelvin to Fahrenheit instantly: °F = (K − 273.15) × 9/5 + 32. Free K to °F calculator with absolute-zero awareness, decimal precision, no signup.
kelvin to rankine
Convert Kelvin to Rankine (K to °R) instantly with our free online converter. Accurate °R = K × 9/5 formula, examples, conversion table and step-by-step...
rankine to celsius
Convert Rankine to Celsius (°R to °C) instantly with our free online converter. Accurate °C = (°R − 491.67) × 5/9 formula, examples, conversion table and...
rankine to fahrenheit
Convert Rankine to Fahrenheit instantly: °F = °R − 459.67. Free °R to °F calculator for US engineering thermodynamics and HVAC computations.
rankine to kelvin
Convert Rankine to Kelvin (°R to K) instantly with our free online converter. Accurate K = °R × 5/9 formula, examples, conversion table and step-by-step...
Voltage Conversion 1
All Voltage Units
Convert all voltage units instantly. Volts, millivolts, microvolts, kilovolts, megavolts in one tool. Free online converter with formulas and conversion table.
Developer Tools 1
Utilities 1
Subnet Calculator
Free IPv4 subnet calculator with CIDR to subnet mask, Cisco wildcard mask, VLSM splitting, binary view, and reverse host sizing (pick the prefix for N hosts).
Geography & Mapping Tools 1
Carbon Footprint Calculator
Free carbon footprint calculator for your household. Track CO2 emissions per year from transport, flights, home energy, diet & shopping, plus offset cost.
