# Scientific Converters > Scientific Converters (scientificconverters.com) is a free unit converter for science and engineering. Every factor is stored exactly where the unit is defined exactly, cites NIST SP 811 or the BIPM SI Brochure, and is computed with 50-digit decimal arithmetic. Water/mercury column units state their reference conditions; standard gas flows (sccm, SLPM) are kept separate from actual flows. Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Attribution: "Scientific Converters (scientificconverters.com)". ## Converters - [Length Converter](https://scientificconverters.com/length/): m, km, cm, mm, µm, ft, in, mi, yd, nmi - [Temperature Converter](https://scientificconverters.com/temperature/): °C, °F, K, °R - [Weight and Mass Converter](https://scientificconverters.com/mass/): kg, g, mg, lb, oz, st, t, ton, oz t, ct - [Energy Converter](https://scientificconverters.com/energy/): J, kJ, kWh, kcal, cal, BTU, therm, eV - [Power Converter](https://scientificconverters.com/power/): W, kW, MW, hp, PS, BTU/h, TR, kcal/h - [Force Converter](https://scientificconverters.com/force/): N, kN, lbf, kgf, kip, dyn, ozf, gf - [Torque Converter](https://scientificconverters.com/torque/): N·m, lbf·ft, lbf·in, kgf·cm, kgf·m, ozf·in - [Density Converter](https://scientificconverters.com/density/): kg/m³, g/cm³, g/mL, lb/ft³, lb/gal, mg/L - [Dynamic Viscosity Converter](https://scientificconverters.com/dynamic-viscosity/): Pa·s, mPa·s, cP, P, lbf·s/ft² - [Kinematic Viscosity Converter](https://scientificconverters.com/kinematic-viscosity/): m²/s, mm²/s, cSt, St, ft²/s - [Pressure Converter](https://scientificconverters.com/pressure/): Pa, kPa, psi, bar, inH₂O, mmHg, torr, atm - [Flow Rate Converter](https://scientificconverters.com/flow-rate/): CFM, m³/h, L/min, L/s, GPM, sccm, SLPM - [Face Velocity & Air Permeability Converter](https://scientificconverters.com/face-velocity/): CFM/ft², L/(m²·s), mm/s, cm/s, ft/min - [Area Converter](https://scientificconverters.com/area/): m², cm², mm², ft², in², test areas - [Volume Converter](https://scientificconverters.com/volume/): L, mL, m³, ft³, in³, US gal, imp gal - [Time Converter](https://scientificconverters.com/time/): ms, s, min, h, day ## Calculators - [Face Velocity Calculator](https://scientificconverters.com/calculators/face-velocity/): Face velocity = airflow ÷ face area. Example: 2000 CFM through a 24 × 24 in filter (4 ft²) = 500 ft/min = 2.54 m/s. Solve for velocity, airflow or area. - [Air Permeability Calculator](https://scientificconverters.com/calculators/air-permeability/): Air permeability = flow ÷ test area. Example: 12 L/min through 20 cm² (ISO 9237) = 100 mm/s = 19.69 cfm/ft². Test-head presets for ISO 9237 and ASTM D737. - [SCFM to ACFM Calculator](https://scientificconverters.com/calculators/scfm-to-acfm/): Convert SCFM to ACFM and back with your temperature, pressure and altitude. Example: 100 SCFM at 100 psig and 68 °F = 12.82 ACFM. Six standard references. - [Reynolds Number Calculator](https://scientificconverters.com/calculators/reynolds-number/): Calculate the Reynolds number Re = ρvD/μ (or vD/ν) with any units and see if pipe flow is laminar, transitional or turbulent. Water, air and oil presets. - [Pipe Pressure Drop Calculator](https://scientificconverters.com/calculators/pipe-pressure-drop/): Pressure drop in a full pipe from flow, diameter, length, roughness and fluid, using Darcy–Weisbach with the Colebrook friction factor. Results in Pa, psi, bar. - [Ideal Gas Law Calculator](https://scientificconverters.com/calculators/ideal-gas-law/): Solve PV = nRT for pressure, volume, moles or temperature with any units. Uses the exact gas constant R = 8.314462618 J/(mol·K); 1 mol at STP is 22.414 L. - [Bubble Point Pore Size Calculator](https://scientificconverters.com/calculators/bubble-point-pore-size/): Membrane bubble-point pressure to largest pore diameter, or back, with d = 4γcosθ/ΔP. Presets for water, IPA, ethanol, Galwick and Porewick. - [Ohm's Law Calculator](https://scientificconverters.com/calculators/ohms-law/): Enter any two of voltage, current, resistance and power to get the other two, with V = IR and P = VI. Works with mV, kV, mA, µA, kΩ, MΩ, mW and kW. - [Bulk Unit Converter](https://scientificconverters.com/calculators/bulk-unit-converter/): Paste a list or a spreadsheet column and convert every value at once: pressure, flow, permeability, area, volume and time. Copy to Excel or download CSV. ## Guides - [Air Permeability Units Explained](https://scientificconverters.com/guides/air-permeability-units/): Air permeability is a flow divided by an area, so every air permeability unit is a velocity: 1 L/(m²·s) = 1 mm/s, 1 cm³/(s·cm²) = 1 cm/s = 10 mm/s, and 1 cfm/ft² = 1 ft/min = 5.08 mm/s exactly. - [Pa vs inH₂O for Filter Pressure Drop](https://scientificconverters.com/guides/pa-vs-inh2o-filter-pressure-drop/): One conventional inch of water is exactly 249.08891 Pa, so filter pressure drops convert at about 250 Pa per inH₂O: 125 Pa ≈ 0.50 inH₂O and 1.0 inH₂O ≈ 249 Pa. - [Standard Test Areas in Textile and Membrane Testing](https://scientificconverters.com/guides/standard-test-areas/): ISO 9237 uses a 20 cm² test area (with 5, 50 and 100 cm² alternatives) and ASTM D737 uses 38.3 cm² (about 5.94 in²); permeability is the measured flow divided by that area. - [sccm vs SLPM vs Actual Flow](https://scientificconverters.com/guides/sccm-vs-slpm-vs-actual-flow/): sccm and SLPM are standard flows referenced to fixed conditions (often 0 °C and 101.325 kPa), so they measure the amount of gas; actual flow in cm³/min or L/min is the volume at line conditions: Q_actual = Q_std × (T/T_ref) × (P_ref/P). - [Celsius, Fahrenheit and Kelvin: How the Scales Relate](https://scientificconverters.com/guides/celsius-fahrenheit-kelvin/): °F = °C × 1.8 + 32 and K = °C + 273.15 exactly; a temperature difference converts without the offset, so a 10 °C rise is an 18 °F rise. - [Dynamic vs Kinematic Viscosity (cP vs cSt)](https://scientificconverters.com/guides/dynamic-vs-kinematic-viscosity/): Kinematic viscosity equals dynamic viscosity divided by density, ν = μ/ρ; in practical units cSt = cP ÷ (density in g/cm³), so an oil of 90 cP and 0.9 g/cm³ is 100 cSt. ## Key conversions - [centimeter to inch](https://scientificconverters.com/length/centimeters-to-inches/) - [kilogram to pound](https://scientificconverters.com/mass/kilograms-to-pounds/) - [Celsius to Fahrenheit](https://scientificconverters.com/temperature/celsius-to-fahrenheit/) - [millimeter to inch](https://scientificconverters.com/length/millimeters-to-inches/) - [meter to foot](https://scientificconverters.com/length/meters-to-feet/) - [kilometer to mile](https://scientificconverters.com/length/kilometers-to-miles/) - [centimeter to foot](https://scientificconverters.com/length/centimeters-to-feet/) - [gram to ounce](https://scientificconverters.com/mass/grams-to-ounces/) - [inch to foot](https://scientificconverters.com/length/inches-to-feet/) - [Celsius to Kelvin](https://scientificconverters.com/temperature/celsius-to-kelvin/) - [meter to yard](https://scientificconverters.com/length/meters-to-yards/) - [pound to ounce](https://scientificconverters.com/mass/pounds-to-ounces/) - [kilowatt to horsepower](https://scientificconverters.com/power/kilowatts-to-horsepower/) - [kilocalorie to kilojoule](https://scientificconverters.com/energy/kilocalories-to-kilojoules/) - [newton-meter to pound-foot](https://scientificconverters.com/torque/newton-meters-to-pound-feet/) - [kilowatt-hour to BTU](https://scientificconverters.com/energy/kilowatt-hours-to-btu/) - [psi to bar](https://scientificconverters.com/pressure/psi-to-bar/) - [kilopascal to psi](https://scientificconverters.com/pressure/kilopascal-to-psi/) - [pascal to inch of water](https://scientificconverters.com/pressure/pascal-to-inch-of-water/) - [pascal to psi](https://scientificconverters.com/pressure/pascal-to-psi/) - [millimeter of mercury to kilopascal](https://scientificconverters.com/pressure/millimeter-of-mercury-to-kilopascal/) - [atmosphere to psi](https://scientificconverters.com/pressure/atmosphere-to-psi/) - [inch of mercury to millibar](https://scientificconverters.com/pressure/inch-of-mercury-to-millibar/) - [millibar to pascal](https://scientificconverters.com/pressure/millibar-to-pascal/) - [torr to pascal](https://scientificconverters.com/pressure/torr-to-pascal/) - [megapascal to psi](https://scientificconverters.com/pressure/megapascal-to-psi/) - [cubic foot per minute to cubic meter per hour](https://scientificconverters.com/flow-rate/cubic-feet-per-minute-to-cubic-meters-per-hour/) - [cubic foot per minute to liter per second](https://scientificconverters.com/flow-rate/cubic-feet-per-minute-to-liters-per-second/) - [US gallon per minute to liter per minute](https://scientificconverters.com/flow-rate/gallons-per-minute-to-liters-per-minute/) - [sccm to SLPM](https://scientificconverters.com/flow-rate/sccm-to-slpm/) - [liter per minute to cubic meter per hour](https://scientificconverters.com/flow-rate/liters-per-minute-to-cubic-meters-per-hour/) - [cubic foot per square foot per minute to liter per square meter per second](https://scientificconverters.com/face-velocity/cfm-per-square-foot-to-liters-per-square-meter-per-second/) - [meter per second to foot per minute](https://scientificconverters.com/face-velocity/meters-per-second-to-feet-per-minute/) - [square meter to square foot](https://scientificconverters.com/area/square-meters-to-square-feet/) - [square centimeter to square inch](https://scientificconverters.com/area/square-centimeters-to-square-inches/) - [liter to US gallon](https://scientificconverters.com/volume/liters-to-us-gallons/) - [cubic meter to cubic foot](https://scientificconverters.com/volume/cubic-meters-to-cubic-feet/) - [hour to minute](https://scientificconverters.com/time/hours-to-minutes/) ## Reference - [How we verify conversion factors](https://scientificconverters.com/methodology/) - [Editorial policy](https://scientificconverters.com/editorial-policy/) - [Changelog](https://scientificconverters.com/changelog/) - [Full unit list with exact factors](https://scientificconverters.com/llms-full.txt) ## Optional - [HTML sitemap](https://scientificconverters.com/sitemap/)