How do I convert between the various measurements?

Common U.S. Volume Measurements:

• 1 tbsp = 3 tsp
• 1 fl oz = 2 tbsp
• 1 cup = 8 oz
• 1 pint = 2 cups
• 1 quart = 4 cups
• 1 gallon = 4 quarts

Common U.S. to Metric Conversions:

• 1 oz ~ 30 mL
• 1 cup ~ 237 mL
• 1 quart ~ 1 L
• 1 oz = 28.4 g
• 1 lbs = 0.45 kg

Common Metric to U.S. Conversions:

• 1 kg = 2.2 lbs

Online Converters:

• Google: Type a conversion such as "1 tbsp in mL" and it will automatically convert it for you. This is generally the fastest option.

• Wolfram Alpha: Same idea, gives you a little more information and lets you disambiguate between similar measurements (e.g. US tablespoons vs. UK tablespoons).

• Convert-Me - Cooking Ingredients: Converts to every well-known measurement at the same time. Can convert (approximate) volume to weight and vice versa, for many ingredients.

• Food.com Measurement Converter: Same thing, a little easier to use, but slower.

iPhone/iPad:

• Kitchen Calculator
• ConvertBot
• Smart Chef Conversions
• Cookulator
• Convert
• ...or just search the App Store.

Android:

• Unit Converter Ultimate
• Cooking Conversions
• ...or just search the Play Store.

Printable Conversion Charts

• Cooking Measurement Equivalents (InfoPlease)
• Measurement and Conversion Charts (StartCooking)
• Conversion Tables (Delia Online)
• Converting Recipes to Metric Measures (The Metric Kitchen)
• Heirloom Weights & Measures (About.com) - archaic/non-standard measurements

(Note: Use your browser's "print selection" feature to print just the conversion chart)

Found this to be very helpful:

If you are serious about cooking, buy some of the measuring cups with multiple different scales, similar to this one:

Not only you will not have to convert the units, because many of the cups have both US and metric scales, but you avoid weighting flour, sugar etc. Real time saver.

From wikipedia:

• teaspoon (tsp): 1/6 ounce
• tablespoon (tbsp): 3 tsp, 1/2 oz
• fluid ounce (fl oz): 2 Tbsp, 1 oz
• jigger (jig): 3 tbsp, 1.5 oz
• cup (c): 16 tbsp, 8 oz
• pint (pt): 2 c, 16 oz ("A pint's a pound the world around" - both have 16 ounces.)
• quart (qt): 2 pt, 32 oz
• gallon (gal): 4 qt, 128 oz

So, this is my first answer on stackexchange and I'm new here. Hello to the community :D The answers above are very good, but I want to add one more app where the cooking units can be converted very quickly. For example for cups, quarts or liter:

• 4 cups (US) to quarts (US)
• 4 liters to cups (US)

For more conversions you can see the latest conversions of the volumes category directly on the website.

Disclaimer: I'm a programmer and developer, and work on my project CalculatePlus in my spare time. This free tool allows you to do quick online calculations and conversions.

If you're trying to convert to metric, and you're getting your recipes from the web, you can also use a browser plugin I wrote which I believe is more convenient than the other suggested solutions, since it displays the conversion result directly in the recipe when you press a button: Everything in […] was added by this plugin. It also converts from volume to weight for many common ingredients (e.g. "10 tablespoons sugar" is converted to "125g").

The plugin is available for Firefox and for Chrome (free software with no ads. I wrote it as a birthday gift :-).