OPINION
JOHNSON, J.,delivered the opinion of the Court,
joined by MEYERS, PRICE, HOLCOMB, and COCHRAN, JJ.Appellee was charged by a single indictment with three counts of aggravated sexual assault. Appellee made an open plea of guilty before the trial court, and the trial court initially sentenced him to 25 years’ incarceration in the institutional division of the Texas Department of Criminal Justice. On the same day, after an off-the-record “victim impact statement” allo-cution, the trial court held an in-chambers discussion with the attorneys regarding the court’s reconsideration of the sentence. The trial court, over the state’s objection, then reassessed appellee’s sentence at 15 years’ incarceration. The state appealed. The court of appeals sustained the state’s sole issue, reversed the judgment of the trial court, and remanded the cause to the trial court for reinstatement of the sentence originally assessed and the corresponding judgment of conviction. State v. Aguilera, 130 S.W.3d 134 (Tex.App.-El Paso, 2003). Appellee petitioned for discretionary review.
We granted review of appellee’s sole issue, which asserts that the court of appeals erred in holding that Texas trial courts do not have the inherent power to vacate, modify, or amend their sentences downward within the time of their plenary power. The state argues that, once a defendant has been given a valid sentence, the trial court has no authority to change that sentence.
Appellee suggests that a trial judge should have the ability, upon reflection, to reform a defendant’s sentence downward when the interests of justice require it and complains that the court of appeals stated that the present case is different from McClinton v. State, 38 S.W.3d 747 (Tex.App.-Houston [14th Dist.] 2001, pet. dism’d, improvidently granted), yet failed to distinguish them. He cites Williams v. State, 145 Tex.Crim. 536, 170 S.W.2d 482, 486 (App.1943), for the principle that a trial court has full power and control of its judgments, orders, and decrees, and suggests that Powell v. State, 124 Tex.Crim. 513, 63 S.W.2d 712 (App.1933), and its progeny prohibit reforming a sentence upward, but do not prohibit reforming downward, as the trial court did in this case.
The state asserts that, once a valid sentence has been imposed, as it was here, the trial court has no authority to change that sentence. The state also argues that a trial court does not have plenary power to do something simply because there is no authority prohibiting such an *697action and that, because there is no express authority by statute or rule permitting the re-sentencing that occurred here, the trial court could not do so. The state further asserts that, even if there is plenary jurisdiction for a trial court to modify a previously imposed sentence, re-sentencing is statutorily prohibited by Tex.Code Ckim. PROC. Art. 42.09, § 1, which provides that a defendant’s sentence begins to run on the day that it is pronounced.1 It further argues that permitting such a modification of a valid sentence could permit victim-impact statements to affect the fact finder at punishment in contravention of the Legislature’s intent that such statements not affect the punishment.2
In Harris v. State, 153 S.W.3d 394 (Tex.Crim.App.2005), we recently held that: 1) a trial court improperly re-sentenced a defendant one day after having initially sentenced him to an authorized, valid sentence; 2) the original sentence imposed was legal and authorized; 3) the second attempt at sentencing violated the defendant’s rights under the Double Jeopardy Clause; and 4) the second, twenty-five-year, sentence was an unauthorized and unconstitutional fifteen-year increase over the initial ten-year sentence. Id. at 397-98. While we noted that the trial court could have properly used its plenary power to modify the sentence if the new sentence was within the same statutory range of punishment,3 our decision was based on a constitutional violation, re-sentencing the defendant to a term of imprisonment that was outside of the statutory range of punishment rather than on a claim of plenary power to modify. Id. Harris is clearly different from the issue presented here, as the re-sentencing was done the next day and there can be no dispute that Harris had begun serving his sentence.
The procedural status of the case is relevant to our decision here. The appel-lee plead to the trial court without a plea bargain, thus the trial court’s choice of sentence was limited only by the applicable statute. If appellee had plead pursuant to a plea bargain and the trial court had accepted the agreement, the sentence could not be changed without appellee’s consent, as he would then be entitled to withdraw his plea. Absent a sentence not authorized by the applicable statute, a trial court may not alter a sentence assessed by a jury, but if the defendant elects sentencing by the judge after a jury trial, the situation is analogous to the open plea we are presented with here.
At a minimum, a trial court retains plenary power to modify its sentence if a motion for new trial4 or motion in arrest of judgment5 is filed within 30 days *698of sentencing.6 We hold that a trial court also retains plenary power to modify its sentence if, as in this case, the modification is made on the same day as the assessment of the initial sentence and before the court adjourns for the day.7 The re-sentencing must be done in the presence of the defendant, his attorney, and counsel for the state. Such modifications comport with the provisions of Article 42.09, § 1, that a defendant’s sentence begins to run on the day that it is pronounced,8 and the provisions of Tex.Code CRiM. Peoc. Art. 42.03, § 1(a), that a felony sentence shall be pronounced in the defendant’s presence. In such circumstances, a trial court has the authority to re-sentence a defendant after assessing an initial sentence if the modified sentence is authorized by statute.
In this case, the trial court was acting within its authority when, only a few minutes after it had initially sentenced appellee and before it had adjourned for the day, it modified appellee’s sentence.9 *699Appellee’s sole ground for review is sustained. The court of appeals is reversed, and the trial court’s sentence of fifteen years’ incarceration is reinstated.
WOMACK, J., filed a concurring opinion. COCHRAN, J., filed a concurring opinion, in which PRICE, J., joined. KEASLER, J., filed a dissenting opinion in which HERVEY, J., joined. KELLER, P.J., and HERVEY, J., dissented.. The provision in Article 42.09, § 1, that a defendant's sentence “begins to run on the day it is pronounced" did not preclude the trial court from re-sentencing appellee on the same day on which he was initially sentenced.
. The state did not assert, in its sole issue in the court of appeals, that the modification was based on an improper consideration of the victim-impact statement. Neither did it raise the issue in a cross-petition to appellee’s petition for discretionary review. We therefore do not address the question of whether the trial court modified the sentence on an improper basis.
. Id. at 396, n. 4. In the instant cause, Aguil-era’s subsequent fifteen-year sentence was within the same first-degree-felony range of punishment as was his initial twenty-five-year sentence and was not an unconstitutional modification of that initial sentence. In addition, the modification made in Harris required the trial court to make an additional finding at the time of re-sentencing: the enhancement allegations were true. In this case, the trial court altered only its determination of what term of years constituted the appropriate sentence.
. Tex. Rule of App. Proc. 21.4.
. Tex. Rule of App. Proc. 22.3.
. We note that we have held that a plea of guilty to the court results in a unitary trial. Caroll v. State, 975 S.W.2d 630, 631 (Tex.Crim.App.1998). We have also held that a trial court cannot grant a new trial as to only the punishment phase of a trial. State v. Hight, 907 S.W.2d 845, 847 (Tex.Crim.App.1995). However, a trial court may properly entertain a motion for new trial, grant it, rehear the defendant’s plea, and re-sentence him, and it does not thereby violate the prohibition against a grant by a trial court of a new trial as to punishment only.
. Concurring opinions from this Court have touched on the subject of plenary power. See. e.g., Awadelkariem v. State, 974 S.W.2d 721, 728-29 (Tex.Crim.App.1998)(Meyers, J., concurring)("a court has inherent power to correct, modify, vacate, or amend its own rulings” and, as long as it does not, by its ruling, divest itself of jurisdiction or exceed a statutory time limit, it can simply change its mind on a ruling. "The ability to do so is a necessary function of an efficient judiciary.” Id. at 729.); McClinton, 121 S.W.3d at 769, n. 1 (Cochran, J., concurring)("Clearly a trial court has plenary jurisdiction over a case for at least the first thirty days after sentencing because it has the authority to receive a motion for new trial (or motion in arrest of judgment) within that time period and to resolve the merits of that motion within 75 days after sentencing.”).
At least two courts of appeals have held that a trial court has the right to re-sentence a defendant within 30 days. Junious v. State, 120 S.W.3d 413, 417 (Tex.App.-Houston [14th Dist.] 2003, pet. ref'd)(trial court had inherent power within the time of its plenary jurisdiction to alter the defendant's sentence (motion for new trial timely filed; 25 years reduced to 10 years pursuant to plea bargain 15 days after original adjudication and sentencing)); Ware v. State, 62 S.W.3d 344, 353-55 (Tex.App.-Fort Worth 2001, pet. ref'd)(motion for new trial timely filed; a trial court in criminal cases possesses inherent power to correct, modify, vacate, or amend its own rulings (erroneously entered illegal sentence of 75 years reduced to legal sentence of 10 years by nunc pro, tunc order 12 days after original sentencing)); McClinton, 38 S.W.3d at 747, 750-51 (Tex.App.-Houston [14th Dist.] 2001, pet. dism'd)(trial court's re-sentencing merely amended its ruling within its plenary power (12 years reduced to 10 years 20 days after original sentencing)). Under our holding today, only the decision in McClinton is incorrect.
. TDCJ calculates the beginning of a sentence by date. Exactly when on a given day the sentencing occurred does not affect the calculation. A sentence pronounced at 10:00 a.m. has exactly the same sentencing date as a sentence pronounced at 4:30 p.m. It is thus meaningless to say that a defendant began serving his sentence at 9:30 a.m.; he began serving it on the day, not at the time, of sentencing.
. We observe that a trial court has discretion to grant a motion for new trial in the interest of justice even though that basis is not specifically enumerated in the rules of appellate procedure. State v. Gonzalez, 855 S.W.2d 692, 694 (Tex.Crim.App.1993). However, a trial court does not have authority to grant a new trial on its own motion; there must be a timely motion for such by the defendant. Zaragosa v. State, 588 S.W.2d 322 (Tex.Crim.App.1979); Harris v. State, 958 S.W.2d 292 (Tex.App.-Fort Worth 1997, pet. ref'd).