Position sizing sounds solved until you trade something other than EURUSD in a USD account. Nine threads on the board cover the mechanics and the common mistakes, and between them they make a decent reference, so here it is in one place.
The formula
The variable stops thread gives it plainly: lots = (account × risk%) / (stop in pips × pip value per lot). With a 20,000 account at 0.5 percent, that's 100 at risk. A 6 pip EURUSD stop is about 1.66 lots, a 12 pip stop about 0.83. If your stops come from structure and change every trade, size has to be recalculated every trade, otherwise "0.5 percent risk" is just a phrase.
The volatility-adjusted sizing thread makes the same point from another side. One percent risk doesn't mean the same lot or the same stop. GBPJPY might move three times what EURCHF does, so the stop adapts to the market and the size adapts to the stop. A reply notes this applies within one pair too: EURUSD in quiet Asia can have half the ATR of the London open.
Where the pip value changes
- JPY pairs. A reply in the JPY and gold thread does the arithmetic: a pip on one lot of USDJPY is 1,000 yen, about $6.70 at 150 and about $10 at 100. If USDJPY moves several big figures, an old sizing table is wrong.
- Gold. On many brokers one lot is 100 ounces, so a $10 move is $1,000 per lot. Copying a lot size from a EURUSD trade onto gold because the stop looks similar on the chart is a classic over-risk.
- Non-USD accounts. The pip value thread converts from the quote currency to the account currency. EURUSD in a EUR account at 1.10 is about €9.09 a pip, not €10. Crosses like GBPJPY in a EUR account need converting from JPY.
The EA lot sizing thread is a good warning for anyone who codes. A sizing function that worked on EURUSD in testing was badly wrong on USDJPY and gold because of tick value and tick size differences. The replies add two more: tick value reported by the platform can be off when the account currency isn't the quote currency, and volume steps differ by symbol, with some brokers only allowing 0.1 steps on certain instruments. The calculators thread says the same for any tool: test it on gold, a JPY pair and an exotic before you trust it.
Tight stops and the size jump
The 0.25R stop thread raises something less technical. Cutting an 8 pip stop to 2 pips at the same 0.5 percent risk means four times the lot size. The risk is the same on paper, but slippage and spread are now a much bigger share of the stop, and the bigger lot number on screen does things to your head. That thread was openly still working out how to handle it.
Tools
A pre-built sizing table, a script or a panel. The table thread suggests rows of stop sizes, columns of pairs, and a reply warns against building it on rounded pip values for crosses. Panels are fastest but must be allowed on your account. The journal thread on tick size adds the last check: log pips and points clearly, because a "15" that might be 150 makes the journal useless.
Has your sizing tool ever been wrong on a specific symbol? Which one, and how did you notice?
Threads this pulls from
- A Position Sizing Table You Can Build in Ten Minutes
- Position Sizing With Variable Stops: Keeping Risk Constant
- Position Sizing Across Pairs, Why JPY and Gold Need Extra Care
- Lot sizing function gotchas across JPY pairs and gold, the bug that over-risked me
- Pip Value in a Non-USD Account: Converting Risk Correctly
- Volatility-Adjusted Sizing: Same Risk, Different Lot Sizes
- Position size for 0.25R stop on EURUSD without revenge upsizing
- Tick size vs pip value mistakes that inflate your P&L journal
- Position-Size Calculators: Script, Panel or Spreadsheet?
