Loch Duntelchaig (from the Scottish Gaelic Loch Dun Seilcheig) is a freshwater loch in the traditional county of Inverness-shire in the Scottish Highlands.

It extends 5 kilometres (3.1 mi) from the southwest to its outflow in the northeast and measures up to 1.75 kilometres (1.09 mi) at its widest.

The loch drains via Loch a Chlachain into the River Nairn.

Loch Duntelchaig is over 60 metres (200 ft) deep towards its south end.

[1] It is also the main reservoir for Inverness sitting less than a kilometre from the secondary reservoir Loch Ashie.