Yes, you may use United miles to fly Singapore Airlines. To understand how many miles are required, you should see the United website, specifically the Star Alliance award chart. This is the only trusted source.

Singapore is not releasing many business and first awards to the Star Alliance partners right now because they have new seating they are fiercely protective of. But they do still have some.

What class of service and flight are you interested in? We can help you determine your odds.