As an exchange student going to Singapore, you are entitled to an INK grant from KI.
On average, the daily expenses in Singapore are much lower than those in Stockholm. One huge difference is in the cost of eating out vs the cost of cooking - eating out can cost as little as 4 SGD/meal, while buying groceries is much more pricey.
In general, in Singapore it is important to have cash as not many places have the POS terminals for cards. There are some apps available such as Swish, however you will need to have a Singaporean bank account. (Grab has a Swish function called GrabPay which does not require a Singaporean bank account :))
I did not get a SG bank account as I did not think it was necessary; you will be charged every time you use an ATM, but you could try and take out larger amounts to avoid the multiple charges, or you could get a Revolut card before leaving.
Food: Singapore is known for its hawker center culture - everywhere you go, you can find a food court offering a variety of cuisines - from Chinese to Malay to Japanese to Western. This way of dining is standard for the locals and it proves really cheap and convenient, and delicious too. Meals can go from 3-10 SGD, depending on stall, location, meal, etc. Usually it comes out to 5-6 SGD/meal; the Western food stalls are the ones that are more expensive. You can find different canteens everywhere on campus, at the dorms, and all around Singapore. In fact, there are some famous stalls that have earned Michelin stars, but be prepared to queue for at least an hour and a half to grab a plate.
There are also some food delivery apps available such as Grab Food, Foodpanda and Deliveroo, where you could order food from different hawker centers and restaurants, and this is usually more expensive (~20 SGD minimum).
If eating out at a restaurant, prepare to pay at least twice what you would pay at a hawker center, oftentimes even more than that.
Transport: Easiest way to go around campus is by using the free internal shuttle buses. There are a few apps available where you could check the timetables (NUS NextBus, NUS Buses), however none of them are accurate enough, so you will have to see for yourself. Outside of campus, the subway (MRT) is most convenient. Their underground network is great, and you can use Google Maps to get around. There are a few different public transport apps available, but I found that none of them were as accurate and easy to work with as Google Maps. The access card is called the EZlink card and you can get one in any convenient store or at the subway station and top it up using the automatic top-up machines there. The EZlink card is for both the MRT and the buses, and also for the SentosaExpress (if you decide to go to Sentosa Island).Additionally, you can use the EZlink card for doing laundry.
Public transport is fairly cheap, but it stops before midnight, even on the weekend. In that case you'll have to call a cab or a Grab. Grabs are a bit cheaper, and if you are going out with friends from your dorm you can split the costs, making it ~5 SGD each, which is really convenient.
Nightlife: Singaporean nightlife is one of the more costly expenses you will have, with both entrance fees and alcohol prices on the expensive side. Entrance can be anywhere between 10-30 SGD, and drinks can go up to 30 SGD, with some places selling cocktails for 39 SGD+. To avoid this you could sign up for different Facebook groups such as Hazel's Guestlist or the NUS Exchangers group, where the admins regularly post discounts or events with free entry for students, both throughout the week and during the weekend. Additionally, you could go to bars during their Happy Hour when drinks are discounted. The party areas of Singapore are mainly Clarke Quay and Holland Village, but there are bars and clubs all throughout. Additionally, hawker centers offer drinks for relatively low prices.
Travels: Singapore's location provides the best opportunity for travelling to the neighboring countries. It could be difficult to take time off while doing full-time research, however you should try and organize a trip or two at least. And while accommodation may be relatively inexpensive, keep in mind that if you decide to book flight tickets last minute, they can cost up to 200 SGD+. And depending on where you are from and where you are going, you might have to account for visa costs and processing time.
Phone plan: Singapore has a small number of phone providers, with SingTel and StarHub being the most popular choices. Both offer prepaid SIM cards, however from my experience the deals StarHub has are much better. You could buy a SIM card and top-up using an app. Their schemes include mainly mobile data and some calls, but no international calls, so you would have to use Messenger, WhatsApp, Viber, etc. It is a bit difficult to explain how their system works, but there is a StarHub kiosk at Changi, so you could get a SIM right away and they will tell you how it all works. Additionally, you could get a SIM or top up at 7Eleven or Cheers.