diff --git a/tools.yml b/tools.yml
index a91527e..5d5c5ae 100644
--- a/tools.yml
+++ b/tools.yml
@@ -214,13 +214,55 @@ tools:
     cores: 6
     mem: 24
   toolshed.g2.bx.psu.edu/repos/bgruening/hifiasm/hifiasm/.*:
-    cores: 20
-    mem: 120
+    cores: 10
     rules:
-    - id: tpvdb_hifiasm_small_input_rule
-      if: input_size <= 0.2
-      cores: 6
-      mem: 40
+    - id: tpvdb_hifiasm_expert_memory_rule
+      # The memory requirement of Hifiasm depends on the "Estimated haploid genome size" (hg_size).
+      # If hg_size is set, and it can be calculated automatically, then we can fit memory more efficiently.
+      # This is done for example in the VGP workflows.
+      if: |
+        parameters = {p.name: p.value for p in job.parameters}
+        parameters = tool.params_from_strings(parameters, app)
+
+        advanced_options = parameters.get("advanced_options", dict())
+        hg_size = advanced_options.get("hg_size", "")
+
+        bool(hg_size)
+      mem: |
+        from math import ceil
+
+        parameters = {p.name: p.value for p in job.parameters}
+        parameters = tool.params_from_strings(parameters, app)
+
+        advanced_options = parameters.get("advanced_options", dict())
+
+        kcov_default = 36
+        kcov = advanced_options.get("kcov", kcov_default)
+
+        hg_size = advanced_options.get("hg_size", "")
+
+        value = 0
+        if hg_size:
+            conversion_factors = {
+                "k": 1000000,
+                "M": 1000,
+                "G": 1,
+            }
+            conversion_factors = {
+                key.lower(): value for key, value in conversion_factors.items()
+            }
+            suffix = hg_size[-1:].lower()
+            value = hg_size[:len(hg_size) - 1]
+            value = value.replace(",", ".")
+            value = float(value)
+            # compute hg size in Gb
+            value = value / conversion_factors[suffix.lower()]
+            value = ceil(value * (kcov * 2) * 1.75)
+
+        # return the amount of memory needed
+        value
+
+
   toolshed.g2.bx.psu.edu/repos/bgruening/infernal/infernal_cmbuild/.*:
     cores: 10
     mem: 20