Free tools
Calculators and checkers you can use now.
Each tool does one job, shows the official rule or rate behind its answer, and says when we last checked that rule against the source. They give general information, not advice, and nothing you type leaves your browser.
Air purifier size calculator for a Singapore room (smoke CADR)
Free air purifier size calculator for Singapore: enter your room in metres or feet and see the smoke CADR NEA’s air pollution FAQs say to look for.
Checked 3 October 2026
Electricity cost calculator for Singapore appliances
Free electricity cost calculator for Singapore: watts, hours and your tariff give kWh and S$ a year, plus an A-versus-B comparison with payback on the price.
Checked 3 October 2026
GST on overseas purchases: the S$400 rule calculator
Free calculator for GST on overseas purchases in Singapore: see whether GST is charged at checkout or due at import under IRAS’s S$400 rule, and the amount.
Checked 3 October 2026
Unit price calculator: which pack costs less per 100 g?
Free unit price calculator for shoppers: compare two or three packs by price per 100 g, 100 ml or item. Handles kg, litres, multipacks and per-sheet goods.
Checked 3 October 2026