Translation guide
How to express that something will happen or be done after a small number of days, typically 2–4 days from now.
The speaker refers to a point in time roughly 2–4 days in the future.
Neutral and common. Literally 'a few days later/after'. Used in both speech and writing.
I'll come again in a few days.
We will inform you of the results in a few days.
Very common in casual and spoken Japanese. Literally '2–3 days later'. Implies a short, indefinite wait.
I'll call again in a few days.
Means 'within a few days'. Emphasizes that the action will happen sometime during the next few days.
I'll contact you in a few days.
Formal/written. Means 'in the near future' or 'shortly', often used in business contexts. Can imply a slightly longer span than 'a few days'.
We will send you the details in a few days.
The speaker refers to the time needed to complete something, meaning 'in the span of a few days'.
The speaker refers to something that happens repeatedly with an interval of a few days.
While 何日か後 (なんにちかご) can mean 'after some days', it sounds like 'after an unknown number of days' and is less natural for the fixed expression 'in a few days'. Use 数日後 or ２、３日後 instead.
I'll come after some days. (unnatural)