The prices seem to change based on special exhibitions, so why not head to the National Museum website for the most up-to-date information. Just google it as Tripadvisor won't allow me to post a direct link to their admissions page.
I was there recently, Sep. 2017, and the prices for non-citizens and non-permanent residents were SG$15 for adults, SG$10 for seniors (60+), students and people with disabilities.
the actual entry is free, but we paid about $25-30 to see a World Treasures Exhibition. Was well worth it !
It's free for Singaporeans and PR. For the rest it's $8-9 and for the British history exhibit its $15
We are both over 60, and so paid 5$ each. The usual adult fee is 10 $ . These are Singapore dollars.
For the basic tour - "Citizens and Permanent Residents
Children 6 years of age and below (All nationalities) - Free*
Foreign Visitors (Adults) - S$10.00
Foreign Visitors (Concessions for Students & Seniors aged 60 years and above and Persons with Disabilities*) - S$5.00"
There are visiting exhibitions with separate pricing. You can go to their website for more details.
Get quick answers from National Museum of Singapore staff and past visitors.
3 Days in Singapore