A governor at Wakefield City Academy was still over the drink-drive limit at 4pm on Saturday following a Friday night out.
City magistrates heard how police stopped John Allott in his Mercedes E320 on Ings Road on March 30.
Allott, 58, was breathalysed and found to be almost double the legal limit.
An apologetic Allott, of Westfield Park, Wakefield, admitted driving with excess alcohol when he appeared before magistrates on Tuesday.
Allott, who was not legally represented, told the court: “First, I would like to apologise.
“I’m very remorseful about the situation.
“It has caused me a lot of stress subsequently.
“It was a very serious lapse of judgement on my part.
“If I can use the term, I got in to holiday-mode prematurely.
“I went out with friends on Friday evening in to the early hours.”
Allott said he was not driving on the Friday night and only had one drink the following day.
He added: “On Saturday I made the mistake of driving the car.
“I wasn’t drinking during the daytime, it was the subsequence of the night before.”
Bench chairman Steve Jones sentenced Allott to an 18-month driving ban and fined him £385 plus £38.50 victim surcharge and £85 costs.
John Anderson, chairman of governors at Wakefield City Academy - formerly Wakefield City High School - said: “I have always found him to be fully supportive, fully dedicated and he always works hard for Wakefield City Academy.”