Spilled is the U.S./American English spelling for the past tense of “to spill”:
Spilt is the U.K./British English spelling for the past tense of “to spill”:
When to Use Spilled vs. Spilt
This is actually a regional spelling difference for the same word, specifically the difference between British English and American English.
Both spilled and spilt have the same meaning, the past tense of the verb “to spill.” The only difference between the two is that spilled is the standard spelling for American English and spilt is the standard spelling for British English.
Strictly speaking, neither spelling is incorrect within its own region. But, like other regional spelling variants (color/colour, labor/labour, fiber/fibre, spelled/spelt), a variant will look odd to those accustomed to the other spelling. Be careful to use the correct spelling within the correct region.
The word spilled is the most common American spelling of the past tense of the verb “to spill,” which means “to cause or allow something to fall or flow over” (as in “a spilled drink”).
The word spilt is the most common U.K. spelling of the past tense of the verb “to spill” (as in “a spilt drink”).
Examples of Spilled vs. Spilt
(In this sentence, the American version is used.)
(In this sentence, the U.K. version is used.)