diff --git a/include/psa/crypto_sizes.h b/include/psa/crypto_sizes.h
index f51ec87..2df315c 100644
--- a/include/psa/crypto_sizes.h
+++ b/include/psa/crypto_sizes.h
@@ -85,6 +85,40 @@
         PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_512 ? 64 :       \
         0)
 
+/** The input block size of a hash algorithm, in bytes.
+ *
+ * Hash algorithms process their input data in blocks. Hash operations will
+ * retain any partial blocks until they have enough input to fill the block or
+ * until the operation is finished.
+ * This affects the output from psa_hash_suspend().
+ *
+ * \param alg   A hash algorithm (\c PSA_ALG_XXX value such that
+ *              PSA_ALG_IS_HASH(\p alg) is true).
+ *
+ * \return      The block size in bytes for the specified hash algorithm.
+ *              If the hash algorithm is not recognized, return 0.
+ *              An implementation can return either 0 or the correct size for a
+ *              hash algorithm that it recognizes, but does not support.
+ */
+#define PSA_HASH_BLOCK_LENGTH(alg)                                  \
+    (                                                               \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD2 ? 16 :            \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD4 ? 64 :            \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD5 ? 64 :            \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_RIPEMD160 ? 64 :      \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_1 ? 64 :          \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_224 ? 64 :        \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_256 ? 64 :        \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_384 ? 128 :       \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512 ? 128 :       \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512_224 ? 128 :   \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512_256 ? 128 :   \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_224 ? 144 :      \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_256 ? 136 :      \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_384 ? 104 :      \
+        PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_512 ? 72 :       \
+        0)
+
 /** \def PSA_HASH_MAX_SIZE
  *
  * Maximum size of a hash.