I stuck to a $15 budget at McDonald's and Burger King. One chain offered more variety.

I tried to order as much food as possible for under $15 at McDonald's and Burger King.

Erin McDowell/Business Insider

• Sticking to a budget can prove difficult, especially with fast food getting more expensive.
• I tried to order as much food as possible for under $15 at McDonald's and Burger King.
• I used deals from both chains' mobile apps to save money.

Trying to spend less than $15 at a fast-food joint and still get a full meal can be harder than finding the last fry at the bottom of the McDonald's bag.