What is contract size in forex and MT5?

Contract size in forex is the number of units that 1.00 lot represents: 100,000 units of the base currency on a currency pair, commonly 100 troy ounces on gold, 5,000 ounces on silver, and whatever the broker sets on index CFDs. MT5 shows it as Contract size in each symbol’s Specification window.

MetaTrader’s help defines it as the “number of units of the commodity, currency or financial asset in one lot” (MT5 help: Market Watch). It is the multiplier between a price move and your result. For forex symbols, MQL5 gives the profit as (close price − open price) × contract size × lots (MQL5 symbol properties).

Common contract sizes in forex, metals and indices

The gold and silver figures match the units of the COMEX gold and silver futures, but a CFD broker can use any size it likes. The table shows what is common, not what your broker uses.

Worked example: same lot, different contract

Where to find contract size in MT5

1. Open Market Watch: View → Market Watch, or Ctrl+M.
2. Right-click the symbol and choose Specification.
3. Read Contract size, and next to it Tick size and Tick value.

Tick value ÷ tick size is what a 1.0 price move is worth on 1.00 lot. On a symbol quoted in your account currency it equals the contract size: on EURUSD with a USD account, 1.00 ÷ 0.00001 = 100,000. If the two do not agree, ask your broker which is right. An Expert Advisor reads the same number as SYMBOL_TRADE_CONTRACT_SIZE.

Common mistake: assuming the textbook size

A lot size copied from a video, a signal or another broker assumes the same contract. On forex pairs that usually holds. On gold, silver and indices it often does not, and a “0.10 lot” habit can be ten times the position you meant. A large contract also collides with the minimum lot size: if the minimum lot of a symbol already risks more than you set, no smaller order exists.

Recalculate for each new symbol and broker with the position size calculator or the gold lot size calculator. How to calculate lot size covers the index case in detail.

Contract size and PipWarden

PipWarden does not assume contract sizes. The EA, which runs in MT5 on your Windows PC or VPS, reports each symbol’s contract size, tick size and tick value and volume limits from your broker. Every trade is sized from the tick size and tick value, then fitted to the volume limits. A different contract at another broker changes the lot size, not the risk per trade you set. Which brokers work, and what they need to allow, is on the brokers page.