wiggle room

The space, time, or freedom to make changes as needed. Good news—I've done the math, and we have enough wiggle room in the budget to make some of those purchases we've been putting off. When I'm meeting up with someone, I always leave early, so that I have wiggle room in case I get lost.

wiggle room

Flexibility, leeway, especially in a negotiation. This slangy expression dates from the mid-1900s. For example, “This contract is too vague; it leaves too much wiggle room for various interpretations.”