is delivering files in a different format out of scope?

Almost never. If the conversion is a straight export with no rework and the result is a standard format anyone in your field would expect, charging for it costs you more in goodwill than it earns in revenue. Treat trivial exports as part of being easy to work with. Save the line-drawing for requests that involve actual labor — rebuilding source, re-rendering, or re-authoring — where the time is real and the format is genuinely a separate deliverable rather than a different wrapper on the same one.

That's usually a different deliverable entirely, not a format swap. Editable source — layered design files, project files, raw footage, uncompiled code — represents your working method and ongoing leverage, and many contracts deliberately exclude it unless the client buys it explicitly. Treat a request for source as a request for a new, priced item, and say so without apology: the flattened or compiled deliverable was the agreement; the editable originals are available as a separate purchase if they want full handoff.

It obligates you to the reasonable industry default for your work, and nothing more specific — which is exactly the ambiguity to fix. 'Final files' with no format named means you owe a usable, standard deliverable, but it gives neither side a clear answer when the client wants something particular. Honor the standard expectation for this one, then tighten the clause next time to list exact formats and explicitly state whether editable source is included. The vagueness isn't your fault, but it is yours to resolve going forward.

Price it by the effort to produce it, not by treating it as a discount on the original. If converting means rebuilding the deliverable in a new tool or re-authoring it for a different platform, that's production time with its own value, and a flat fee for the converted deliverable is cleaner than an hourly meter. Quote it as a standalone line: 'the [format] version is $X.' Keeping it a fixed number stops the client from feeling like they're being charged twice for one thing and keeps the conversation about the new file, not the old one.

Not the core answer, but it's worth a little grace. If a client wants a format that's newly common or newly relevant since your agreement, neither of you could have scoped it at signing, so a hard 'that's extra' can feel rigid. Weigh the effort: if it's a quick export, absorb it as keeping the work current. If it's real labor, explain that it's a genuinely new deliverable rather than something you should have anticipated, and price it as the fresh work it actually is.

It prevents most of them outright. A deliverables clause that names exact formats — and states plainly whether editable source files are part of the deal — removes the interpretation gap that every format argument grows in. When the client asks for something off the list, you point at the clause rather than improvising a justification, and the conversation becomes 'here's the add-on price' instead of 'I thought that was included.' One specific sentence in the contract is worth far more than the cleverest explanation after the fact.