A long time ago I found a nice little application handy at displaying Windows’ uptime. It’s been running fine on any version since Windows XP all the way up to the (disastrous) 8.
Simply download and extract the uptime.exe executable to your Windows, System32 or SysWOW64 folder and you’ll be able to use it by simply typing uptime in a Command Prompt.
UPTIME, Version 1.01 (C) Copyright 1999, Microsoft Corporation Uptime [server] [/s ] [/a] [/d:mm/dd/yyyy | /p:n] [/heartbeat] [/? | /help] server Name or IP address of remote server to process. /s Display key system events and statistics. /a Display application failure events (assumes /s). /d: Only calculate for events after mm/dd/yyyy. /p: Only calculate for events in the previous n days. /heartbeat Turn on/off the system's heartbeat /? Basic usage. /help Additional usage information.