diff --git a/src/uu/factor/benches/factor_bench.rs b/src/uu/factor/benches/factor_bench.rs
index 952ea09a616..f2f4c331221 100644
--- a/src/uu/factor/benches/factor_bench.rs
+++ b/src/uu/factor/benches/factor_bench.rs
@@ -3,23 +3,195 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore funcs
+// spell-checker:ignore funcs semiprimes
 
 use divan::{Bencher, black_box};
+use num_bigint::BigUint;
+use num_prime::nt_funcs::{factorize64, factorize128, factors};
+use std::collections::BTreeMap;
 use uu_factor::uumain;
 use uucore::benchmark::run_util_function;
 
-/// Benchmark multiple u64 digits
-#[divan::bench(args = [(2)])]
-fn factor_multiple_u64s(bencher: Bencher, start_num: u64) {
-    bencher
-        // this is a range of 5000 different u128 integers
-        .with_inputs(|| (start_num, start_num + 2500))
-        .bench_values(|(start_u64, end_u64)| {
-            for u64_digit in start_u64..=end_u64 {
-                black_box(run_util_function(uumain, &[&u64_digit.to_string()]));
-            }
-        });
+// Internal algorithm benchmarks avoid CLI parsing and stdout overhead.
+
+fn factorize(n: &BigUint) -> (BTreeMap<BigUint, usize>, Option<Vec<BigUint>>) {
+    match n.bits() {
+        0..=64 => {
+            let n_u64 = n
+                .try_into()
+                .expect("value with at most 64 bits fits in u64");
+            let factors = factorize64(n_u64)
+                .into_iter()
+                .map(|(factor, count)| (BigUint::from(factor), count))
+                .collect();
+            (factors, None)
+        }
+        65..=128 => {
+            let n_u128 = n
+                .try_into()
+                .expect("value with at most 128 bits fits in u128");
+            let factors = factorize128(n_u128)
+                .into_iter()
+                .map(|(factor, count)| (BigUint::from(factor), count))
+                .collect();
+            (factors, None)
+        }
+        _ => factors(n.clone(), None),
+    }
+}
+
+#[divan::bench]
+fn factorize_small_u64(bencher: Bencher) {
+    bencher.bench(|| {
+        for n in 2u64..=100 {
+            black_box(factorize(&BigUint::from(n)));
+        }
+    });
+}
+
+#[divan::bench]
+fn factorize_32bit_semiprime(bencher: Bencher) {
+    let n = BigUint::from(4_295_098_369_u64);
+
+    bencher.bench(|| {
+        black_box(factorize(&n));
+    });
+}
+
+#[divan::bench]
+fn factorize_64bit_semiprime(bencher: Bencher) {
+    let n = BigUint::from(18_446_743_979_220_271_189_u64);
+
+    bencher.bench(|| {
+        black_box(factorize(&n));
+    });
+}
+
+#[divan::bench]
+fn factorize_large_prime(bencher: Bencher) {
+    let n = BigUint::from(18_446_744_073_709_551_557_u64);
+
+    bencher.bench(|| {
+        black_box(factorize(&n));
+    });
+}
+
+#[divan::bench]
+fn factorize_close_factors(bencher: Bencher) {
+    let n = BigUint::from(4_294_049_777_u64);
+
+    bencher.bench(|| {
+        black_box(factorize(&n));
+    });
+}
+
+#[divan::bench]
+fn factorize_96bit_composite(bencher: Bencher) {
+    let n = BigUint::parse_bytes(b"19807040619342712411247977", 10).unwrap();
+
+    bencher.bench(|| {
+        black_box(factorize(&n));
+    });
+}
+
+#[divan::bench]
+fn factorize_120bit_mixed(bencher: Bencher) {
+    let n = BigUint::parse_bytes(b"1329227995784915872903807060280344217", 10).unwrap();
+
+    bencher.bench(|| {
+        black_box(factorize(&n));
+    });
+}
+
+// End-to-end benchmarks include CLI parsing and output formatting.
+
+/// Benchmark small u64 numbers via CLI.
+#[divan::bench(args = [(2, 502)])]
+fn factor_small_u64(bencher: Bencher, (start, end): (u64, u64)) {
+    bencher.bench(|| {
+        for n in start..=end {
+            black_box(run_util_function(uumain, &[&n.to_string()]));
+        }
+    });
+}
+
+/// Benchmark a longer sequential u64 workload.
+#[divan::bench(args = [(2, 2502)])]
+fn factor_multiple_u64s(bencher: Bencher, (start, end): (u64, u64)) {
+    bencher.bench(|| {
+        for n in start..=end {
+            black_box(run_util_function(uumain, &[&n.to_string()]));
+        }
+    });
+}
+
+/// Benchmark medium u64 values including 32-bit semiprimes.
+#[divan::bench(args = ["4295098369", "3215031751", "2147483647"])]
+fn factor_medium_u64(bencher: Bencher, number: &str) {
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &[number]));
+    });
+}
+
+/// Benchmark large u64 primes.
+#[divan::bench(args = ["18446744073709551557", "9223372036854775783"])]
+fn factor_large_u64_prime(bencher: Bencher, number: &str) {
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &[number]));
+    });
+}
+
+/// Benchmark the PR timing cases as end-to-end utility runs.
+#[divan::bench(args = [
+    "18446744073709551557",          // 64-bit prime near 2^64
+    "9999999999999999999",           // large u64 composite
+    "123456789012345678901234567890", // 97-bit u128 composite
+    "18446743979220271189",          // 64-bit semiprime
+])]
+fn factor_pr_timing_cases(bencher: Bencher, number: &str) {
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &[number]));
+    });
+}
+
+/// Benchmark a 64-bit semiprime made from two 32-bit primes.
+#[divan::bench]
+fn factor_64bit_semiprime(bencher: Bencher) {
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["18446743979220271189"]));
+    });
+}
+
+/// Benchmark a 96-bit composite.
+#[divan::bench]
+fn factor_96bit_composite(bencher: Bencher) {
+    let n = "19807040619342712411247977";
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &[n]));
+    });
+}
+
+/// Benchmark a 120-bit composite with mixed factor sizes.
+#[divan::bench]
+fn factor_120bit_mixed(bencher: Bencher) {
+    let n = "1329227995784915872903807060280344217";
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &[n]));
+    });
+}
+
+/// Benchmark multiple numbers in sequence.
+#[divan::bench]
+fn factor_batch_mixed(bencher: Bencher) {
+    let test_numbers = ["2", "1000000007", "4295098369", "18446743979220271189"];
+
+    bencher.bench(|| {
+        for n in test_numbers {
+            black_box(run_util_function(uumain, &[n]));
+        }
+    });
 }
 
 fn main() {