diff --git a/libaegisub/common/charset_conv.cpp b/libaegisub/common/charset_conv.cpp
index 514f364ec4..b0825e0194 100644
--- a/libaegisub/common/charset_conv.cpp
+++ b/libaegisub/common/charset_conv.cpp
@@ -358,38 +358,6 @@ size_t IconvWrapper::Convert(std::string_view source, std::span<char> dest) {
 	return dest.size() - dstLen;
 }
 
-size_t IconvWrapper::RequiredBufferSize(std::string_view str) {
-	return RequiredBufferSize(str.data(), str.size());
-}
-
-size_t IconvWrapper::RequiredBufferSize(const char* src, size_t srcLen) {
-	char buff[4096];
-	size_t charsWritten = 0;
-	size_t res;
-
-	do {
-		char* dst = buff;
-		size_t dstSize = sizeof(buff);
-		res = conv->Convert(&src, &srcLen, &dst, &dstSize);
-		conv->Convert(nullptr, nullptr, &dst, &dstSize);
-
-		charsWritten += dst - buff;
-	} while (res == iconv_failed && errno == E2BIG);
-
-	if (res == iconv_failed) {
-		switch (errno) {
-			case EINVAL:
-			case EILSEQ:
-				throw BadInput(
-					"One or more characters in the input string were not valid "
-					"characters in the given input encoding");
-			default:
-				throw ConversionFailure("An unknown conversion failure occurred");
-		}
-	}
-	return charsWritten;
-}
-
 bool IsConversionSupported(const char *src, const char *dst) {
 	iconv_t cd = iconv_open(dst, src);
 	bool supported = cd != iconv_invalid;
diff --git a/libaegisub/include/libaegisub/charset_conv.h b/libaegisub/include/libaegisub/charset_conv.h
index 9f2a9ddfb9..29a6b52c47 100644
--- a/libaegisub/include/libaegisub/charset_conv.h
+++ b/libaegisub/include/libaegisub/charset_conv.h
@@ -93,16 +93,6 @@ class IconvWrapper {
 	/// @param[out] dest Buffer to place the result in
 	/// @return Number of bytes written to dest
 	size_t Convert(std::string_view source, std::span<char> dest);
-
-	/// @brief Get the required buffer size required to fit the source string in the target charset
-	/// @param source A string in the source charset
-	/// @param sourceSize Length of the source in bytes
-	/// @return Bytes required, including NUL terminator if applicable
-	size_t RequiredBufferSize(const char* source, size_t sourceSize);
-	/// @brief Get the required buffer size required to fit the source string in the target charset
-	/// @param str A string in the source charset
-	/// @return Bytes required, not including space needed for NUL terminator
-	size_t RequiredBufferSize(std::string_view str);
 };
 
 /// Is the conversion from src to dst supported by the linked iconv library?