Calculator.com
- Includes general and scientific calculators; currency, mortgage, lease and loan calculators; and time, temperature, unit, area, and measurement converters.
Martindale's Calculators On-Line Center
- Includes calculators of agriculture, archeology, astronomy, bioscience, chemistry, engineering, geoscience, mathematics, meteorology, physics, radiation, and statistics.
IRS Withholding Calculator
- Calculate and estimate withholding taxes. Useful for tax preparation and W-4 preparation.
