できれば・できたら

できれば and できたら both mean “if possible” but differ in level of formality and nuance. できれば is slightly more formal or polite and is often used in written or polite conversation, while できたら is more casual and common in everyday speech. Both are used to soften requests, to hedge statements, or to propose something with flexibility. They introduce a condition under which something would be done or preferred, rather than making a direct imperative. They can be used for requests, preferences, or tentative plans, and are often followed by requests or time limits to make the tone considerate.