Risk-Based Forex Lot Sizing Across Account and Quote Currencies

Summary

The document explains how to size a forex position so that a stop-loss represents a chosen amount of account-currency risk. It distinguishes three currency relationships: a pair whose quote currency matches the account currency, a pair whose base currency matches it, and a pair containing neither. The first two cases use a direct conversion or the current ask price; the third requires a cross rate through an intermediate currency. The example code searches for that conversion pair in either currency order and selects it for access to its quote.

The post supplies formulas and implementation snippets, but no worked numerical example or empirical evaluation. It notes a practical limitation in strategy testing: the required intermediate symbol may need a fixed quote added as an entry. Correct sizing also depends on contract specifications, point value, stop distance, and reliable currency conversion quotes, details the article does not fully validate. The formulas are presented as implementation guidance rather than a tested, universally applicable sizing routine.

Key ideas

• Risk-based sizing aims to limit the loss at the stop to a specified share or amount of account equity.
• The conversion formula depends on whether the account currency is the pair's quote currency, base currency, or neither.
• When neither pair currency matches the account currency, the method uses an intermediate conversion pair.
• The code checks both possible currency orders when locating that intermediate pair.
• The post warns that a strategy tester may need a fixed quote for the conversion symbol.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.