Let G be a
(
k
+
1
)
‐connected or
(
k
+
1
)
‐edge‐connected graph, where
k
∈
ℕ
. The k‐fault‐diameter and k‐edge‐fault‐diameter of G is the largest diameter of the subgraphs obtained from G by removing up to k vertices and edges, respectively. In this paper we give upper bounds on the k‐fault‐diameter and k‐edge‐fault‐diameter of graphs in terms of order. We show that the k‐fault‐diameter of a
(
k
+
1
)
‐connected graph G of order n is bounded from above by
n
−
k
+
1
, and by approximately
4
k
+
2
n
if G is also triangle‐free. If G does not contain 4‐cycles then this bound can be improved further to approximately
5
n
(
k
−
1
)
2
. We further show that the k‐edge‐fault‐diameter of a
(
k
+
1
)
‐edge‐connected graph of order n is bounded by n – 1 if k = 1, by
⌊
2
n
−
1
3
⌋
if k = 2, and by approximately
3
k
+
2
n
if
k
≥
3
, and give improved bounds for triangle‐free graphs. Some of the latter bounds strengthen, in some sense, bounds by Erdös, Pach, Pollack, and Tuza (J Combin Theory B 47 (1989) 73–79) on the diameter. All bounds presented are sharp or at least close to being optimal. © 2017 Wiley Periodicals, Inc. NETWORKS, Vol. 70(2), 132–140 2017