Science
1,125 science calculators for chemistry, physics, biology, astronomy and the Earth sciences. Each one states the relation it uses and the units it expects, so class problems, lab work and quick checks come out right, free in your browser.
Pipe resonance calculator
A 0.5 m pipe open at both ends, with sound at 343 m/s, resonates at 343 Hz and then at 686, 1029, 1372 and 1715 Hz.
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Sound intensity calculator
A 1 W source spreads its sound over a sphere, so 1 m away the intensity is 0.079577471546 W/m². Enter the acoustic power and the distance to get the intensity…
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Decibel calculator
An intensity of 0.000001 W/m² is a million times the hearing threshold, which is a level of 60 dB.
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Speed of sound calculator
At 20 °C sound crosses dry air at about 343 m/s, compared with 331.3 m/s at 0 °C. Enter the air temperature in Celsius, Kelvin or Fahrenheit to get the speed of…
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Standing wave calculator
On a 1 m string vibrating in its second harmonic, the wavelength is 1 m and the nodes sit at 0, 0.5 and 1 m.
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Wave speed on a string calculator
Enter the string tension and its linear mass density to get the speed of a transverse wave, v = √(T/μ): 100 N on a string of 0.01 kg/m gives 100 m/s.
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Wave speed calculator
Give any two of frequency, wavelength and wave speed and get the missing one from v = fλ: a 50 Hz wave with a 2 m wavelength travels at 100 m/s.
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Beam deflection calculator
A load of 48 at the center of a simply supported span of 2, with a modulus of 200 and a moment of inertia of 4 in consistent units, gives a maximum deflection…
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Bending stress calculator
A moment of 1000 N·m at 0.05 m from the neutral axis, in a section with a moment of inertia of 0.0001 m⁴, gives a bending stress of 500000 Pa by σ = My/I.
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Gear ratio calculator
A 20-tooth driver turning a 40-tooth gear gives a ratio of 2, a speed reduction: 1000 rpm in becomes 500 rpm out.
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Shear stress calculator
A shear force of 500 N spread over 0.002 m² gives an average shear stress of 250000 Pa from τ = F/A.
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Stress calculator
A force of 1000 N on 0.0001 m², one square centimetre, gives 10 MPa of tensile stress from σ = F/A, shown in pascals and megapascals.
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Thermal stress calculator
A steel bar fixed between rigid walls, with the usual modulus of steel, α of 0.000012 per kelvin and a 50 K rise, develops 120 MPa of compressive stress from σ…
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Young's modulus calculator
A stress of 200 MPa at a strain of 0.001 gives a Young’s modulus of 200 GPa, typical of structural steel, from E = σ/ε.
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Area thermal expansion calculator
A 2 m² plate with an area coefficient of 0.000024 per kelvin, heated by 50 K, gains 0.0024 m² and ends at 2.0024 m².
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Bernoulli equation calculator
Water at 101325 Pa flowing at 2 m/s, 10 m up, reaches 144358.25 Pa at 4 m/s and 5 m: the drop in height adds more pressure than the faster flow removes.
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Boyle's law calculator
A gas at pressure 2 and volume 3 compressed to pressure 6 ends at volume 1, because P1·V1 = P2·V2 keeps the product at 6.
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Buoyancy calculator
Displacing 0.002 m³ of water at 1000 kg/m³ under Earth gravity of 9.81 m/s² gives an upward push of 19.62 N.
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Celsius to Fahrenheit calculator
Water freezes at 0 °C, which is 32 °F: enter a value, say whether it is Celsius or Fahrenheit, and see both scales side by side.
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Pipe flow continuity calculator
A pipe narrowing from 0.02 to 0.01 m² with water entering at 3 m/s pushes it out at 6 m/s, carrying 0.06 m³/s throughout.
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Partial pressure calculator
Oxygen at a mole fraction of 0.21 in air at 1 atm has a partial pressure of 0.21 atm. Enter one fraction or the whole mixture plus the total pressure, and each…
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Entropy change calculator
Absorbing 1,000 J of heat at 300 K raises a system's entropy by about 3.33333333333 J/K. Enter the heat and the absolute temperature, and the result follows ΔS…
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Mixing temperature calculator
Mix 100 g at 80 °C with 200 g at 20 °C, both with a specific heat of 4.184, and they settle at 40 °C.
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Gas density calculator
Dry air at 101325 Pa and 273.15 K weighs about 1.29 kg per cubic metre. Enter absolute pressure, molar mass and kelvin temperature to get the ideal-gas density…
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Molar volume calculator
At 101325 Pa and 273.15 K one mole of ideal gas fills about 0.0224 m³, the classic 22.4 litres. Enter absolute pressure and kelvin temperature to get the molar…
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Gay-Lussac law calculator
A sealed gas at 1 atm and 273.15 K heated to 373.15 K rises to about 1.3660992129 atm. Enter the starting pressure and kelvin temperature plus one final value…
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Specific heat calculator
Heating 2 kg of a material with a specific heat of 500 J/(kg·K) by 10 K takes 10000 J. Enter mass, specific heat and the temperature change, and the heat energy…
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Hydrostatic pressure calculator
Ten metres down in water of 1000 kg/m³ with gravity at 9.81 m/s², the gauge pressure is 98100 Pa. Enter density, depth and gravity, and add the atmospheric…
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Ideal gas law calculator
One mole at 101325 Pa filling 0.0224 m³ sits just below 273.15 K. Give any three of pressure, volume, amount of gas and temperature, and the ideal gas law…
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Isothermal work calculator
One mole of ideal gas that doubles its volume at 300 K does 1728.9438964613 J of work. Enter the moles, the kelvin temperature and the volume ratio to get the…
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Kelvin converter
Type 25 °C and you get 77 °F and 298.15 K side by side. Each reading passes through the kelvin scale first, so the three values always agree, and anything…
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Linear thermal expansion calculator
A 10 m steel beam with α of 0.000012 per kelvin heated by 50 K grows 0.006 m, ending at 10.006 m. Enter the original length, the expansion coefficient and the…
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Newton's law of cooling calculator
Coffee at 90 °C in a 20 °C room, with a cooling constant of 0.05 per minute, has cooled to 62.457146179884 °C after 10 minutes.
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Pressure calculator
A force of 1000 N spread over 0.5 m² makes 2000 Pa, which is 0.02 bar. Enter any two of force, area and pressure to get the third, with the pressure given in…
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Relative humidity calculator
An actual vapour pressure of 1.5 kPa against a saturation pressure of 2.5 kPa means 60 % relative humidity.
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Reynolds number calculator
A fluid of 1000 kg/m³ moving at 2 m/s through a 0.05 m pipe, with a viscosity of 0.001 Pa·s, gives a Reynolds number of 100000, which points to turbulent flow.
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Specific heat capacity calculator
If 4184 J warm 1 kg of a sample by 1 K, its specific heat is 4184 J/(kg·K), the classic value for water.
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Heat conduction calculator
A 12 m² wall 0.2 m thick, with a conductivity of 0.8 W/(m·K) and 25 K between its faces, lets 1200 W of heat through.
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Thermal efficiency calculator
An engine that delivers 300 J of work from 1000 J of heat runs at 30 % efficiency and rejects 700 J.
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Rate constant from rate law calculator
A rate of 0.002 with A at 0.1 (first order) and B at 0.2 (second order) gives a rate constant k of 0.5 and an overall order of 3.
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Absolute humidity calculator
At 30 °C and 60 % relative humidity the air holds roughly 18 g of water vapour per cubic metre; at 5 °C the same 60 % is barely 4 g.
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pH acidity classifier
A pH of 3.5 is acidic and sits 3.5 units from neutral. Enter any measured or calculated pH and get its label, acidic below 7, neutral at 7 and basic above 7…
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Battery charge capacity calculator
Find the most charge an electrode material can hold: 0.1 mol with one electron per formula unit stores 9648.53321 C, also given in ampere-hours and…
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Buffer pH after acid addition
See how far a buffer's pH falls when strong acid goes in: adding 0.02 mol to 0.1 mol each of weak acid and conjugate base with pKa 4.76 leaves 0.12 mol and 0.08…
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Buffer pH calculator
Get the pH of a weak-acid buffer from pKa and two concentrations: with pKa 4.76 and 0.1 mol/L each of acid and conjugate base, the pH is exactly 4.76.
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Half-cell reduction potential calculator
Adjust a table reduction potential to the ion concentration you actually have: copper at 0.1 mol/L, with E° of 0.34 V and two electrons, reads below 0.34 V.
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Equilibrium moles from total pressure calculator
Turn equilibrium ratios into real amounts: at 2 atm in 10 L and 298.15 K, relative amounts of 1:2:1 become mole fractions of 0.25, 0.5 and 0.25, with partial…
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Electrochemical equivalents calculator
Turn the charge passed through a cell into electrochemical equivalents: 96,485.3321 coulombs is exactly one equivalent, one faraday and one mole of electrons.
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Electrolysis charge calculator
Find the charge that flows during electrolysis: 2.5 A for 3600 seconds carries 9000 coulombs, along with the matching moles of electrons.
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First-order concentration calculator
See how much reactant is left after a first-order reaction has run: 1 mol/L with k of 0.1 per second falls to 0.367879441171 mol/L after 10 seconds, or 1/e of…
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Concentration cell potential calculator
Silver ions at 0.001 and 0.1 mol/L form a concentration cell whose voltage comes from that hundredfold difference, since the standard potential is zero.
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Titration unknown concentration
25 mL of 0.1 N titrant that neutralizes a 50 mL sample means the sample is 0.05 N. Enter the titrant normality, the titrant volume at the end point and the…
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pH from hydrogen ion concentration calculator
0.1 mol/L of hydrogen ions is pH 1, a clearly acidic solution: type a known [H+] in moles per litre and get the pH, its acidic, neutral or basic label and the…
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Strong base pH calculator
0.1 mol/L sodium hydroxide gives pH 13: enter the base concentration and how many hydroxide ions each formula unit releases, and get the hydroxide and hydrogen…
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pKa from buffer pH calculator
A buffer at pH 4.76 with equal amounts of acid and conjugate base points to an acid pKa of 4.76: enter the measured pH and the base-to-acid ratio and get the…
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pKa from Ka calculator
A Ka of 0.000018 gives a pKa of about 4.74, which the calculator rates as a weak acid: enter any positive Ka and get the pKa, a strength band and each…
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pKa + pKb calculator
Acetic acid's pKa of 4.76 means its conjugate base, acetate, has a pKb of 9.24: enter any pKa and get the conjugate pKb from the rule that both add up to 14 in…
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Titration pH before equivalence calculator
Mixing 0.0025 mol of strong acid with 0.001 mol of strong base in 0.05 L leaves 0.0015 mol of acid, so hydrogen ions sit at 0.03 M and the pH falls between 1…
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Zero-order concentration calculator
Starting at 1 mol/L with k of 0.1 mol/L per second, half the reactant is left after 5 seconds. Enter the initial concentration, the zero-order rate constant and…
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Moles of element in compound calculator
2 moles of water hold 4 moles of hydrogen atoms, because the subscript of hydrogen in H2O is 2. Enter the moles of compound and the subscript of the element you…
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