CalcChef tool collection
Science and Engineering Tools
Explore science and engineering calculations with practical tools for formulas, systems, projects, and field work.
Start with these tools
V1, Vr and V2 Takeoff Speed Calculator
V1, Vr and V2 in knots from weight, wing area, thrust, flaps, runway, altitude and temperature, with the balanced field length. Not for flight use.
Refrigerant Charge Calculator
R-410A line-set charge from nameplate charge, line length and liquid-line size: ounces to add or remove and the total. Other refrigerants need a typed rate.
Brake Horsepower Calculator
Calculate brake horsepower from torque and RPM readings. Supports lb-ft and Nm, with kW conversion, wheel HP, and power-to-weight ratio.
Room AC BTU Calculator
Room air conditioner size in BTU/h from floor area by the ENERGY STAR sizing chart, adjusted for sun, people and a kitchen. Not a Manual J calculation.
Molar Mass Calculator
Molar mass of a chemical formula in g/mol from IUPAC atomic weights, with each element’s mass percent. Reads brackets and hydrates such as CuSO4·5H2O.
Kinetic Energy Calculator
Kinetic energy from mass and speed by KE = ½mv², or mass or speed from the energy, in metric or US units, with the result also in kWh, kcal and BTU.
Solar Panel Tilt Angle Calculator
Solar panel tilt and azimuth from your latitude or a city: tilt = latitude for a fixed mount, ±15° by season, a tilt for each month. No yield estimate.
Power Factor Calculator
Power factor from any two of kW, kVA and kVAR, with the phase angle, the line current at your voltage and the capacitor kVAR to reach a target.
Gun Recoil Energy Calculator
Free recoil energy in ft-lbs and joules, plus recoil velocity and momentum, from bullet weight, muzzle velocity, powder charge and gun weight.
All Science and Engineering Tools
44 free browser-based tools
ABV Calculator
Alcohol by volume (ABV) from original and final gravity, by (OG − FG) × 131.25 or an alternate formula, with attenuation and estimated calories.
Appliance Energy Cost Calculator
Running cost of an appliance, or up to five, from watts, hours a day, days a week and your rate: cost per hour, per day, per average month and per year.
Asphalt Tonnage Calculator
Tons of hot mix asphalt for a driveway or lot from length, width and compacted depth, with density (145 lb/ft³ default) and waste, in feet or meters.
Battery Run Time Estimator
Battery run time from mAh and mA at one voltage, or from Wh and watts, times an efficiency you set for converter losses. Shows hours, minutes and Wh.
Brake Horsepower Calculator
Calculate brake horsepower from torque and RPM readings. Supports lb-ft and Nm, with kW conversion, wheel HP, and power-to-weight ratio.
Commute Carbon Footprint
Commute CO2 a year from one-way distance and days a week, using EPA 2025 factors (car 0.297 kg per mile, bus 0.066 per rider) or your mpg or EV figures.
Crop Factor Calculator
Crop factor, equivalent focal length and f-number, and horizontal, vertical and diagonal field of view for eleven sensor sizes or a custom one.
Crosswind Component Calculator
Calculate the crosswind and headwind or tailwind component for a runway from the runway heading, wind direction and wind speed in knots, mph or km/h.
Depth of Field (DOF) Calculator
Depth of field, near and far focus limits and hyperfocal distance from focal length, f-number, subject distance and sensor, in meters or feet.
Dew Point Comfort Zone
Dew point from air temperature and relative humidity by the Magnus formula, with the tool’s own comfort bands from Dry to Very oppressive.
Fertilizer N-P-K Mixer
Blend up to three fertilizers and filler to a target N-P-K: 10-10-10 from urea, triple superphosphate and potash is 21.7%, 21.7%, 16.7% + filler.
Fuel Endurance Calculator
Aircraft fuel endurance to your reserve and to dry tanks, plus range in still air and in wind, from fuel and fuel flow in gal, L, kg or lb and cruise speed.
Glass Weight Estimator
Glass panel weight in kg and lb from length, width, thickness and panel count, at 2.50 g/cm³ for float glass types, or acrylic and polycarbonate sheet.
Gun Recoil Energy Calculator
Free recoil energy in ft-lbs and joules, plus recoil velocity and momentum, from bullet weight, muzzle velocity, powder charge and gun weight.
Kinetic Energy Calculator
Kinetic energy from mass and speed by KE = ½mv², or mass or speed from the energy, in metric or US units, with the result also in kWh, kcal and BTU.
Lightning Distance Calculator
Distance to a lightning strike from the seconds between flash and thunder, at 5 seconds per mile, in miles or km, with what to do at that range.
Molar Mass Calculator
Molar mass of a chemical formula in g/mol from IUPAC atomic weights, with each element’s mass percent. Reads brackets and hydrates such as CuSO4·5H2O.
Molarity Dilution Calculator
Solve C1V1 = C2V2 for any one of the four values: stock or final concentration in M, mM, µM or nM, or stock or final volume in L, mL or µL.
Molarity to Percent Solution Calculator
Molarity to percent and back in % w/v, % w/w or % v/v, from the molar mass and a density where needed, with g/L and presets for stock acids and ethanol.
Mulch & Soil Calculator
Mulch, soil or gravel volume for a rectangular, round or triangular bed: cubic yards or m³, bags to buy, and an approximate weight for wood chips or compost.
ND Filter Exposure Calculator
Find the shutter speed to use with an ND filter. Pick your base shutter speed and the filter strength in stops or ND number (ND8, ND64, ND1000).
Power Factor Calculator
Power factor from any two of kW, kVA and kVAR, with the phase angle, the line current at your voltage and the capacitor kVAR to reach a target.
Pressure Altitude Calculator
Pressure altitude from field elevation and altimeter setting in inHg or hPa, plus an approximate density altitude when you add the outside air temperature.
Pressure Drop Calculator
Pipe pressure drop for water, air or a custom fluid by Darcy-Weisbach, or Hazen-Williams for water, in gpm, inches and psi or metric units.
Propeller Thrust Calculator
Static thrust in N, lbf and kgf from propeller diameter, pitch, RPM and blades in air or water, plus ideal power at your airspeed from momentum theory.
Refrigerant Charge Calculator
R-410A line-set charge from nameplate charge, line length and liquid-line size: ounces to add or remove and the total. Other refrigerants need a typed rate.
Reynolds Number
Reynolds number Re = ρvL/μ, or vL/ν from kinematic viscosity, in SI units with water and air presets, labeled laminar, transitional or turbulent for pipe flow.
Room AC BTU Calculator
Room air conditioner size in BTU/h from floor area by the ENERGY STAR sizing chart, adjusted for sun, people and a kitchen. Not a Manual J calculation.
Signal-to-Noise Ratio (SNR)
Signal-to-noise ratio in dB from two dB levels or from two values: 10 log10 for power, 20 log10 for voltage. Shows the power and amplitude ratios.
Soil Erosion Rate Calculator
Annual soil loss in t/ha/yr and lb/acre/yr from RUSLE, A = R × K × LS × C × P, with topsoil mm/yr and a Low to Very High class.
Solar Insolation by Latitude
Sun-hours above the atmosphere and day length for any latitude and month: 8.8 sun-hours and 14.8 h of daylight at 40°N in June. Not peak sun hours.
Solar Panel Output Calculator
Solar panel output in kWh per day, month and year from peak sun hours, roof area or a panel count, panel watts, losses and tilt, plus CO₂ offset.
Solar Panel Tilt Angle Calculator
Solar panel tilt and azimuth from your latitude or a city: tilt = latitude for a fixed mount, ±15° by season, a tilt for each month. No yield estimate.
Specific Gravity to Brix Converter
Convert specific gravity to °Brix and °Plato, or Brix to SG, from 1.000 to 1.17874 SG (0 to 40 Brix), with hydrometer temperature correction and ABV.
Specific Heat Calculator
Heat to warm or cool a mass of 16 preset materials, from water to copper, or your own specific heat: Q = m × c × ΔT, in J, kJ, MJ or BTU.
Spring Constant Calculator
Spring constant k = F ÷ x by Hooke’s law, or force or stretch from the other two, with stored energy. Force in N, kN, lbf or kgf; k in N/m, kN/m or lbf/in.
Thermal Mass Calculator
Heat stored in a concrete, brick, stone, adobe, water, steel or custom mass from its area, thickness and temperature rise, in kWh or BTU, for passive solar.
Tire Pressure Temperature Calculator
Tire pressure by temperature in °F or °C: the new gauge reading in PSI, kPa or bar, or the cold pressure to set for a target. 32 PSI at 70°F reads 30.2 at 50°F.
V1, Vr and V2 Takeoff Speed Calculator
V1, Vr and V2 in knots from weight, wing area, thrust, flaps, runway, altitude and temperature, with the balanced field length. Not for flight use.
Vampire Power Cost Calculator
Annual, monthly and daily cost of standby power from the number of devices, watts each, hours a day and your rate, with kWh and CO2.
Water Hardness Converter
Convert water hardness between grains per gallon (gpg), mg/L or ppm as CaCO3, mmol/L and German, French and Clark degrees, and see how hard it is.
Wind Chill and Heat Index Calculator (NWS)
NWS wind chill from air temperature and wind speed, and NWS heat index with its category from temperature and humidity, in °F or °C.
Wind Load Calculator (ASCE 7)
Simplified wind pressure in psf and force in lb from wind speed, height, exposure and risk category, in the style of ASCE 7. Not a design calculation.
Wire Gauge Ampacity Calculator
Pick a copper wire size from 14 AWG to 4/0 AWG for a load in amps and a run length, with the voltage drop. An orientation aid, not an NEC compliance check.