Two recently launched trip calculators from TripAdvisor and TravelMuse caught our attention.

TripAdvisor's Vacation Rentals Calculator (which debuted in March) is helpful if you're torn between a vacation rental or a hotel stay. You input your destination and number of guests and nights, and then estimate how often you'll eat meals out. The calculator compares what you'll spend in a hotel versus. a vacation rental. I tested Charleston, New York City, and San Diego, and got mixed results. In Charleston with four guests and three nights, you could save as much as $360 by getting a vacation rental. TripAdvisor offers 36 properties in Charleston, starting at $70 per night. (Incidentally, all of TripAdvisor's reviews come with listings via FlipKey, a vacation rental service.) The calculator said that a vacation rental in San Diego, for two adults and two kids, would be about the same as a hotel, which was helpful information to have.

On the down side, the site lists only four properties in New York City, starting at $425 a night—we've got some hotel deals for less than that.

The moral of the story? This tool works best if you're staying in a smaller, less-urban city, like Charleston or Santa Fe. For more on Vacation Rentals, check out our handbook.

If you're simply looking for inspiration, try TravelMuse's Yaycations Calculator, launched in April. By asking about discretionary purchases (the 20 painful choices include shoes, coffee, and gadgets), the calculator estimates what you could save yearly, turning that money into a vacation budget. Then you pick from a list of trip ideas, such as Urban Endeavors, Single-Parent Travel, and Mountain Vacations, and it'll spit out destination suggestions depending on your budget. You can even book an air/hotel package. You'll probably want to sit down to do your own math before you jet off to Italy or France, but the calculator is a fun way to think twice about your vacation budget.