in for a penny, in for a pound

Idioms  

1. Once involved, one must not stop at half-measures. For example, All right, I'll drive you all the way there—in for a penny, in for a pound. This term originally meant that if one owes a penny one might as well owe a pound, and came into American use without changing the British monetary unit to dollar. [Late 1600s] For a synonym, see hanged for a sheep.

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Example Sentences

A couple in California are in for a penny, in for a pound after finding what they estimate to be a million copper pennies in a basement.

From BBC • Jun. 9, 2023

Use whatever cliche you wish — "in for a penny, in for a pound," "crossing the Rubicon," "down the rabbit hole" — but ultimately it's all the same thing.

From Salon • Jan. 6, 2022

In the case of Amazon, some privacy experts say, it may be a case of in for a penny, in for a pound.

From Los Angeles Times • Nov. 19, 2020

My reasoning was: in for a penny, in for a pound.

From The Guardian • Jun. 21, 2019

In fact, it was rather too much aglow, but Penelope was in for a penny, in for a pound, as they say.

From "The Incorrigible Children of Ashton Place: Book I: The Mysterious Howling" by Maryrose Wood