Calculators

Unit Conversions

There are a lot of nice online unit converters, but they all do different things. Here's an attempt at rationalising them so that everything useful¹ is in one place. Put one quantity in and the others will all change accordingly. Mouseover text on the label of each textbox gives some additional information.

You can type in scientific notation (e.g. you can get 800nm by writing 800E-9 in the wavelength box). I mostly left the quantities in their base units, because:

• It would get very messy with separate cells for MHz, GHz, THz, etc.
• We should all know the prefixes and be able to multiply and divide powers of 10.

The SI prefixes are at the bottom of the page if you've forgotten.

General
Energy (J):		Energy (eV):
Energy (Hartree):		Energy (kWh):
Optical
Frequency (Hz):		Angular Frequency (rad Hz):
Time Period (s):		Wavelength (m):
Wavenumber (m-1):		Angular Wavenumber (m-1):
Chemical
Energy (kJ/mol):		Energy (kcal/mol):
Equivalent Temperature (K):		Spectroscopic Wavenumber (cm-1):
Cell Potential (V):		Boltzmann Population Ratio:
Equilibrium Constant:		ln(Equilibrium Constant):
Rate Constant:		Half Life (s):
Parameters for Chemical Calculations Above
Calculation Temperature (K):		Degeneracy Ratio:
Arrhenius A factor:		Electrons Transferred:
Miscellaneous
British Thermal Units:		Grams of TNT:
Rydbergs:		Ergs:
Barrels of Oil Equivalent:		Calories:

Metric Prefixes

If you're an undergraduate reading this, learn the table below by heart.

atto (a)	femto (f)	pico (p)	nano (n)	micro (μ)	milli (m)	kilo (k)	mega (M)	giga (G)	tera (T)	peta (P)	exa (E)
1E-18	1E-15	1E-12	1E-9	1E-6	1E-3	1E3	1E6	1E9	1E12	1E15	1E18