diff --git a/src/lib.rs b/src/lib.rs
index 29e6095..c7d1846 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,11 @@ const E_MAX: u8 = 4;
 
 static_assertions::const_assert_eq!(M_BITS + E_BITS, 8);
 
+pub const EXACT_INT_MAX: u8 = if E_MAX > M_BITS {
+	2 << M_BITS
+} else {
+	(2 << E_MAX) - 1
+};
 const M_STORAGE_MAX: u8 = (1 << M_BITS) - 1;
 const E_STORAGE_MAX: u8 = (1 << E_BITS) - 1;
 const M_BIAS: u8 = 1 << M_BITS;
@@ -35,8 +40,17 @@ impl F8 {
 }
 
 impl From<u8> for F8 {
-	fn from(value: u8) -> Self {
-		todo!()
+	fn from(v: u8) -> Self {
+		if v == 0 {
+			return Self(0);
+		}
+		let e = v.ilog2() as u8;
+		let off = e as i8 - M_BITS as i8;
+		let m = if off >= 0 { v >> off } else { v << -off };
+		if e > E_MAX {
+			return Self(0xff);
+		}
+		Self::merge(m & M_STORAGE_MAX, e + E_BIAS)
 	}
 }
 
@@ -60,5 +74,8 @@ mod tests {
 		for e in 0..E_MAX {
 			assert_eq!(u8::from(F8::merge(0, e + E_BIAS)), 1 << e, "e={e}");
 		}
+		for k in 0..=EXACT_INT_MAX {
+			assert_eq!(u8::from(F8::from(k)), k);
+		}
 	}
 }