Forex Margin Calculator with FCA Leverage Caps

How the FCA cap sets your margin

The asset class sets the cap and the cap sets the margin: one standard lot of a major pair needs 1/30 of its notional value, £3,333.33 on the worked example, while the same notional in shares needs 1/5 of it. Choose the instrument, enter your size in standard lots, and pick your account currency. The cap applies automatically and shows read-only beside the inputs; it is set by the rules, not by the broker. The results give the notional value, the initial margin, and the equity level where close-out begins.

Margin is not a fee. It is your own money set aside while the position is open, returned when it closes. The costs of the trade are the spread, any commission and overnight financing; our broker cost calculator ranks the first two across the brokers we test, and the position size calculator works back from a risk limit to the size that fits both your stop and this margin.

FCA retail caps by asset class

The caps come from the FCA's CFD rules in COBS 22.5, made permanent in PS19/18 and in force since 1 August 2019. They bind every FCA-authorised firm, so no regulated broker can offer a UK retail client more.

A major currency pair is two currencies from the FCA's list of six: US dollar, euro, Japanese yen, pound sterling, Canadian dollar and Swiss franc. That puts GBP/USD, EUR/GBP and GBP/JPY at 30:1, while a pair with any other currency, AUD/USD or NZD/USD for example, is non-major at 20:1. Relevant sovereign debt (government bonds issued by the UK, a eurozone member state, the US, Japan, Canada or Switzerland) also sits at 30:1; this calculator covers forex and gold, and the full tier detail is in our leverage guide.

There is no crypto row in the table because the FCA banned the sale of crypto derivatives to retail consumers under PS20/10, in force since 6 January 2021; our FCA regulation guide covers what that ban reaches.

Margin maths

Initial margin = notional value x (1 / leverage ratio). For forex, notional is 100,000 units of the base currency per standard lot, converted to your account currency. For gold, it is 100 ounces per lot at spot, priced in our gold CFD guide. The margin percentage is the ratio inverted: 30:1 means 3.33% of notional, 20:1 means 5%, 5:1 means 20%.

Margin scales in a straight line with size: 0.10 lots needs a tenth of the margin of 1.00 lot. It also moves with exchange rates whenever the base currency is not your account currency, which is why the calculator prices notional at the dated rate shown rather than assuming a fixed figure. How margin interacts with equity and free margin is covered in our margin guide.

The 50% close-out rule

At 50% of the initial margin on your open CFDs, the firm must start closing them: on the worked example above that line sits at £1,666.67. The rule is a floor on the whole account, not a warning, and it is set by the same COBS 22.5 rules as the caps. Negative balance protection sits underneath it, so a retail account cannot lose more than the money in it. Both protections stop applying if you elect to be treated as a professional client, which is the trade behind offshore brokers advertising 500:1; our FCA regulation guide covers what professional status actually gives up.

Close-out works across the whole account, not per trade. Two positions each using £3,333.33 of margin share one £3,333.33 close-out level, so a loss on one can force the other shut. Watching free margin matters more than watching any single stop.