Generally 30 days. Which state is involved in the appeal? If it's Massachusetts, look at rule 4 and 14 of the Massachusetts rules of appellate procedure.
Rule 4(b), as amended, 431 Mass. 1601 (2000), reads as follows:
"Appeals in Criminal Cases. In a criminal case unless otherwise provided by statute or court rule, the notice of appeal required by Rule 3 shall be filed with the clerk of the lower court within thirty days after entry of the judgment or order appealed from; or entry of a notice of appeal by the Commonwealth; or the imposition of sentence
"The running of the time for filing a notice of appeal shall be terminated as to the moving party by a motion for a new trial
pursuant to Massachusetts Rules of Criminal Procedure 30 filed in the lower court within thirty days after the verdict or finding of guilt or within thirty days after imposition of sentence and the full time fixed by this rule shall commence to run and shall be computed from the date of entry of an order denying such motion."
(3) Rule 14(b), as amended, 378 Mass. 939 (1979), reads as follows:
"The appellate court or a single justice for good cause shown may upon motion enlarge the time prescribed by these rules or by its order for doing any act, or may permit an act to be done after the expiration of such time; but neither the appellate court nor a single justice may enlarge the time for filing a notice of appeal beyond one year from the date of entry of the judgment or order sought to be reviewed, or, in a criminal case, from the date of the verdict or finding of guilt or the date of imposition of sentence, whichever date is later."