Edgoro
Major forex pairs · Free calculator

GBPUSD lot size calculator

On GBP/USD one pip is 0.0001 and a standard lot is 100,000 GBP, so a pip is worth $10 per 1.00 lot in a USD account. Risking $100 with a 25-pip stop gives 0.40 lots.

Risk per trade
Position size (rounded down to 0.01 lot)
0.40 lots
Risk amount$100.00
Exact size0.4000 lots
Mini lots (0.10)4.00
Micro lots (0.01)40.0
Units40,000 GBP
Value of 1 pip per lot$10.00

USD account. 1 lot = 100,000 GBP; 1 pip = 0.0001. Spread and commission not included.

The calculator opens on the worked example below: a USD account, 1% of $10,000. Trading involves substantial risk of loss and is not suitable for every investor. Edgoro is a software tool, not a broker or financial adviser: nothing it produces is investment advice, and past or backtested performance does not guarantee future results.

What 1 pip is on GBPUSD

GBP/USD, nicknamed cable, is quoted in dollars per pound. 100,000 pounds moving by 0.0001 makes or loses 10 dollars, at 1.25 as at 1.40: like every pair quoted in US dollars, its pip value per lot is fixed for a USD account.

What does change with the price is the size of the position. 1.00 lot at 1.33 is £100,000, about $133,000 of notional, more than a lot of EUR/USD, so the margin per lot is higher even though the risk per pip is identical. MetaTrader quotes it with 5 digits, so 1 pip = 10 points and the tick size is 0.00001.

GBPUSD pip value per lot

Value of one pip (0.0001 in price): 0.0001 × 100,000 = $10 per 1.00 lot.

Position1 pip25 pips (0.0025)
1.00 lot$10.00$250.00
0.10 lot$1.00$25.00
0.01 lot$0.10$2.50

Worked example: 1% of $10,000

  1. Risk: 1% × $10,000 = $100.00.
  2. Stop: 25 pips = 0.0025 in price.
  3. Value of 1 pip per 1.00 lot: $10.00.
  4. Lot size = $100.00 ÷ (25 × $10.00) = 0.4000, rounded down to the 0.01 step: 0.40 lots.

GBP/USD often needs a somewhat wider stop than EUR/USD for the same setup. Sizing from the stop keeps the loss at $100 whatever width the chart asks for.

Contract size and tick value in MT5

In MetaTrader 5, right-click GBPUSD in Market Watch and choose Specification: it shows Contract size, Digits, Profit currency and the volume limits. Tick size and tick value are what MQL5 reads with SYMBOL_TRADE_TICK_SIZE and SYMBOL_TRADE_TICK_VALUE; the script below prints them for your account.

Contract size100,000 GBP
Digits5 (e.g. 1.16253) at most brokers
Tick size (SYMBOL_TRADE_TICK_SIZE)0.00001
1 pip0.0001 = 10 ticks (10 MT5 points)
Profit currencyUSD
Tick value, 1.00 lot (SYMBOL_TRADE_TICK_VALUE)$1.00 in a USD account
Volume stepShown in Specification; 0.01 at most retail brokers

MQL5: lot size from a money risk

A script that sends no order: it reads the contract size, tick size, tick value and volume limits your broker sets for GBPUSD, then prints the lot size that risks 1% of the balance at the stop. The stop is a price distance (0.0025), so the result is the same on 2-, 3- or 5-digit quotes. Save it as MQL5/Scripts/LotSize_GBPUSD.mq5 and compile it in MetaEditor (F7): 0 errors, 0 warnings.

MQL5
//+------------------------------------------------------------------+
//| LotSize_GBPUSD.mq5                                             |
//| Lot size that risks a % of the balance at a given stop distance|
//+------------------------------------------------------------------+
#property script_show_inputs

input string InpSymbol       = "GBPUSD"; // Symbol, exactly as in Market Watch
input double InpRiskPercent  = 1.0;      // Risk per trade, % of balance
input double InpStopDistance = 0.0025;   // Stop-loss distance in price (0.0025 = 25 pips)

// Lots that lose about riskMoney at the stop, rounded down to the volume step.
// Returns 0 when even the minimum volume would risk more than riskMoney.
double LotsForRisk(const string symbol, const double riskMoney, const double stopDistance)
  {
   double tickSize  = SymbolInfoDouble(symbol, SYMBOL_TRADE_TICK_SIZE);
   double tickValue = SymbolInfoDouble(symbol, SYMBOL_TRADE_TICK_VALUE); // 1.00 lot, one tick, account currency
   double step      = SymbolInfoDouble(symbol, SYMBOL_VOLUME_STEP);
   double minLot    = SymbolInfoDouble(symbol, SYMBOL_VOLUME_MIN);
   double maxLot    = SymbolInfoDouble(symbol, SYMBOL_VOLUME_MAX);
   if(tickSize <= 0.0 || tickValue <= 0.0 || step <= 0.0 || stopDistance <= 0.0)
      return 0.0;
   double lossPerLot = stopDistance / tickSize * tickValue;            // money lost by 1.00 lot at the stop
   double lots       = MathFloor(riskMoney / lossPerLot / step + 1e-9) * step;
   if(lots < minLot)
      return 0.0;
   int volumeDigits = (int)MathMax(0.0, MathCeil(-MathLog10(step) - 1e-9));
   return NormalizeDouble(MathMin(lots, maxLot), volumeDigits);
  }

void OnStart()
  {
   if(!SymbolSelect(InpSymbol, true))
     {
      PrintFormat("%s not found: use the exact name from Market Watch (some brokers add a suffix)", InpSymbol);
      return;
     }
   int    digits   = (int)SymbolInfoInteger(InpSymbol, SYMBOL_DIGITS);
   double point    = SymbolInfoDouble(InpSymbol, SYMBOL_POINT);
   double contract = SymbolInfoDouble(InpSymbol, SYMBOL_TRADE_CONTRACT_SIZE);
   double tickSize = SymbolInfoDouble(InpSymbol, SYMBOL_TRADE_TICK_SIZE);
   double tickVal  = SymbolInfoDouble(InpSymbol, SYMBOL_TRADE_TICK_VALUE);
   string currency = AccountInfoString(ACCOUNT_CURRENCY);
   double risk     = AccountInfoDouble(ACCOUNT_BALANCE) * InpRiskPercent / 100.0;
   double lots     = LotsForRisk(InpSymbol, risk, InpStopDistance);

   PrintFormat("%s: contract size %g, %d digits, tick size %s, tick value %g %s per lot",
               InpSymbol, contract, digits, DoubleToString(tickSize, digits), tickVal, currency);
   PrintFormat("Stop %s = %.0f points. Risk %.2f %s",
               DoubleToString(InpStopDistance, digits), InpStopDistance / point, risk, currency);
   if(lots > 0.0)
      PrintFormat("Lot size: %g", lots);
   else
      Print("Even the minimum volume risks more than that: widen the risk or tighten the stop");
  }

The key line is stopDistance / tickSize * tickValue: the money one lot loses at the stop, already converted to your account currency by the terminal. Dividing the risk by it and flooring to SYMBOL_VOLUME_STEP gives the volume to pass to CTrade::Buy() or CTrade::Sell().

Pine Script v6 equivalent

The same sizing on a TradingView chart, from syminfo.pointvalue (money per 1.0 of price per unit) and syminfo.mintick (the chart's tick). Checked by Edgoro Pine Check; paste it into TradingView's Pine Editor to add it to a chart.

Pine Script v6
//@version=6
indicator("GBPUSD lot size for a money risk", overlay = true)

riskMoney    = input.float(100.0, "Risk per trade (account currency)", minval = 0.01)
accountCcy   = input.string("USD", "Account currency")
stopDistance = input.float(0.0025, "Stop-loss distance (price)", minval = 0.0)
contractSize = input.float(100000.0, "Units per 1.00 lot at your broker", minval = 0.0)

// One unit of the symbol gains or loses syminfo.pointvalue (in syminfo.currency) per 1.0 of price
fx          = request.currency_rate(syminfo.currency, accountCcy)
lossPerUnit = stopDistance * syminfo.pointvalue * fx
units       = lossPerUnit > 0 ? riskMoney / lossPerUnit : na
lots        = contractSize > 0 ? math.floor(units / contractSize * 100) / 100 : na

var table info = table.new(position.top_right, 2, 3, bgcolor = color.new(color.gray, 80))
if barstate.islast
    table.cell(info, 0, 0, "Stop")
    table.cell(info, 1, 0, str.tostring(stopDistance / syminfo.mintick, "#") + " ticks of " + str.tostring(syminfo.mintick))
    table.cell(info, 0, 1, "Units")
    table.cell(info, 1, 1, str.tostring(units, "#.####"))
    table.cell(info, 0, 2, "Lots (rounded down)")
    table.cell(info, 1, 2, str.tostring(lots, "#.##"))

On a TradingView forex chart, syminfo.pointvalue is 1: units is an amount of GBP, and 100,000 of them make a lot. request.currency_rate() converts the USD result into your account currency.

Common mistakes on GBPUSD

  • Same pip value, more margin. Sizing by risk works exactly as on EUR/USD, but each lot locks up more margin. Check it in the margin calculator before you stack positions.
  • Data and rate decisions. UK releases and Bank of England decisions can jump past a stop. The lot size caps the loss at the stop price, not at the price you actually get filled at.
  • A GBP account. Dollar profits are converted back to pounds: $10 per pip is about £7.52 at 1.33, so a £100 risk with a 25-pip stop allows 0.53 lots.

Lot size sets how much a trade loses if the stop is hit at its price. It doesn't make a trade a good one, and gaps or slippage can make the loss larger. Trading involves substantial risk of loss and is not suitable for every investor. Edgoro is a software tool, not a broker or financial adviser: nothing it produces is investment advice, and past or backtested performance does not guarantee future results.

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Tools and code for the same job

Want the sizing inside an Expert Advisor?

Describe your GBPUSD strategy in plain English and Edgoro's MT5 EA generator writes the MQL5 Expert Advisor, with risk-based lot sizing like the script above, and compiles it in MetaEditor before you get it. Test it on a demo account: a clean build isn't proof that a strategy works.