diff --git a/lisp/org-colview.el b/lisp/org-colview.el
index 7aa5ef645..da9a11104 100644
--- a/lisp/org-colview.el
+++ b/lisp/org-colview.el
@@ -1345,18 +1345,32 @@ (defun org-columns--summary-estimate (estimates _)
 The mean and variance of the result will be the sum of the means
 and variances (respectively) of the individual estimates."
   (let ((mean 0)
-        (var 0))
+        (var 0)
+        (durationp
+         (catch :no-match
+           (dolist (e estimates)
+             (dolist (val (split-string e "-"))
+               (unless (org-duration-p val) (throw :no-match nil))))
+           'all-values-are-durations)))
     (dolist (e estimates)
-      (pcase (mapcar #'string-to-number (split-string e "-"))
+      (pcase (mapcar
+              (if durationp
+                  #'org-duration-to-minutes
+                #'string-to-number)
+              (split-string e "-"))
 	(`(,low ,high)
 	 (let ((m (/ (+ low high) 2.0)))
 	   (cl-incf mean m)
 	   (cl-incf var (- (/ (+ (* low low) (* high high)) 2.0) (* m m)))))
 	(`(,value) (cl-incf mean value))))
     (let ((sd (sqrt var)))
-      (format "%s-%s"
-	      (format "%.0f" (- mean sd))
-	      (format "%.0f" (+ mean sd))))))
+      (if durationp
+          (format "%s - %s"
+                  (org-duration-from-minutes (- mean sd))
+                  (org-duration-from-minutes (+ mean sd)))
+        (format "%s-%s"
+	        (format "%.0f" (- mean sd))
+	        (format "%.0f" (+ mean sd)))))))