diff --git a/sledge/report/sledge_report.ml b/sledge/report/sledge_report.ml
index 7b9c73b30..85327dc49 100644
--- a/sledge/report/sledge_report.ml
+++ b/sledge/report/sledge_report.ml
@@ -310,22 +310,22 @@ let write_html ranges rows chan =
           <th>Test</th>
           <th>elapsed<br>(sec)</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>user<br>(sec)</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>system<br>(sec)</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>alloc<br>(bytes)</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>promo<br>(bytes)</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>peak<br>(bytes)</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>Status</th>
           <th>&Delta;<br></th>
           <th>Steps</th>
@@ -333,7 +333,7 @@ let write_html ranges rows chan =
           <th>Cover</th>
           <th>%%</th>
           <th>&Delta;<br></th>
-          <th>&Delta;%%<br></th>
+          <th><math><mrow><mfrac><mi>prev</mi><mi>curr</mi></mfrac></mrow></math></th>
           <th>Solver<br>Steps</th>
           <th>&Delta;<br></th>
         </tr>|} ;
@@ -378,21 +378,23 @@ let write_html ranges rows chan =
       in
       let delta max pct t ppf d =
         let r = 100. *. d /. t in
+        let x = (t -. d) /. t in
         Printf.fprintf ppf
           "<td align=\"right\" bgcolor=\"%s\">%12.3f</td>\n\
-           <td align=\"right\" bgcolor=\"%s\">%12.0f%%</td>\n"
+           <td align=\"right\" bgcolor=\"%s\">%12.2fx</td>\n"
           (color max d) d (color pct r)
-          (Base.Float.round_decimal ~decimal_digits:2 r)
+          (Base.Float.round_decimal ~decimal_digits:2 x)
       in
       let delta_mem max pct w ppf d =
         let r = if Float.(abs d < 0.000001) then 0. else 100. *. d /. w in
+        let x = (w -. d) /. w in
         Printf.fprintf ppf
           "<td align=\"right\" bgcolor=\"%s\">%s</td>\n\
-           <td align=\"right\" bgcolor=\"%s\">%12.0f%%</td>\n"
+           <td align=\"right\" bgcolor=\"%s\">%12.2fx</td>\n"
           (color max d)
           Core_kernel.Byte_units.(to_string_short (of_megabytes d))
           (color pct r)
-          (Base.Float.round_decimal ~decimal_digits:2 r)
+          (Base.Float.round_decimal ~decimal_digits:2 x)
       in
       let timed = delta ranges.max_time ranges.pct_time in
       let allocd = delta_mem ranges.max_alloc ranges.pct_alloc in