Buying power represents the amount a user has in his/her account that is available to trade. It is an aggregation across different currencies and is calculated using the latest exchange rates.

Your buying power amount will be different for each market as it is based on the currency the asset is traded in. See below for an illustration of how this works:

Buying power for US assets

USD settled balance + USD unsettled balance + SGD settled balance + HKD settled balance

Buying power for Singapore assets

SGD settled balance + SGD unsettled balance + USD settled balance + HKD settled balance

Buying power for Hong Kong assets

HKD settled balance + HKD unsettled balance + USD settled balance + SGD settled balance 

Example: 

If you have, 

SGD settled balance = S$7,000

SGD unsettled balance = S$3,000

USD settled balance = US$10,000

USD unsettled balance = US$4,000

HKD settled balance = HK$10,000

HKD unsettled balance = HK$5,000

Given the following conversion rates, 

US$1 = S$1.40

S$1 = US$0.75

US$1 = HK$8

S$1 = HK$6

HK$1 = S$0.20

HK$1 = US$0.15

Then, 

Buying power for US assets = US$10,000 + US$4,000 + (S$7,000 * 0.70) + (HK$10,000 * 0.15) = US$20,400

Buying power for Singapore assets = S$7,000 + S$3,000 + (US$10,000 * 1.40) + (HK$10,000 * 0.2) = S$26,000

Buying power for Hong Kong assets = HK$10,000 + HK$5,000 + (US$10,000 * 8) + (S$7,000 * 6) = HK$137,000

What are settled and unsettled balances? 

Settled balance is the available amount that can be withdrawn to your bank account. 

Unsettled balance is the amount that cannot be withdrawn to your bank account. This includes any unsettled trade value from sell trades (there is a 1 day settlement period for US market and 2-day settlement period for Singapore and Hong Kong market after a sell trade before the sale is considered final) and any cash rewards from promotions.