A Beginner's Guide to Forex Lot Size Calculation, Automatic Lot Size Calculator for MetaTrader 4 and 5

A Beginner's Guide to Forex Lot Size Calculation, Automatic Lot Size Calculator for MetaTrader 4 and 5

Introduction to Lot Size Calculation

In forex trading, lot size refers to the volume of currency traded in a transaction i.e. a lot represents the amount of a currency bought or sold in a trade.

There are three categories of lot sizing including:

  • Micro lots: represents 1,000 units of the forex currency pair
  • Mini lots: represents 10,000 units of the forex currency pair 
  • Standard lots: represents 100,000 units of the forex currency pair 

Understanding how to calculate lot size is crucial for managing risk and maximizing profits. According to statistics, a significant percentage of traders fail due to improper lot size calculation, highlighting the importance of mastering this skill.

Importance of Proper Lot Sizing for Traders 

Proper risk management is essential in forex trading to protect capital and ensure long-term success. This means that the lot size selected by a trader can directly influence the level of risk taken in a trade.  The larger a lot size, the higher the profit or loss could be, and therefore the higher the risk.

Other reasons why it is critical to understand lot sizes in forex:

  1. Trading strategies: Different trading strategies require different lot sizes. For example, a swing trading strategy may involve larger lot sizes whilst an intraday trading strategy that involves entering and exiting a trade within a day may consider smaller lot sizes.

  2. Account management: Brokers and proprietary firms require the account to maintain a certain balance in the account and depending on the leverage offered by them, a trader determines which type of account is best suited to their trading strategy.

Choosing an Appropriate Lot Size in Forex 

Selecting a lot size is a crucial decision as it can affect returns, risks and a traders' psychology. Traders should determine this by reviewing their account size, trading strategy and other factors including: 

  • Leverage. Depending on the leverage and limits placed by the trading platform, a trader may have to adjust their lot size  
  • Risk toleranceTraders who are more risk-averse may choose to trade with smaller lot sizes to limit their losses, while other traders may be comfortable taking on larger positions.

Methods to Calculating Lot Sizes in Forex 

Calculating lot sizes in forex ultimately depends on the currency pair you intend to trade and the size of your trading account. 

1. Fixed Lot Size 

In this approach, a trader can choose to use a fixed number of lots on every trade. For example, you could have a fixed stop loss of 25 pips and always use 3 standard lots for each trade.

2. Percentage Risk (Balance or Equity) 

This method allows the trader to calculate their position size based on a percentage of the account a trader is willing to risk per trade. This could be either based on the account's (a) equity or (b) balance amounts, typically around 1%-2% of the total account balance. 

What is the difference between the two? The account balance is all the money in your trading account. Equity is the balance plus/minus any profit/losses from open positions.

Lot size = (account equity or balance x risk percentage) /   (Stop Loss in pips * Pip value per lot)


- Stop loss in pips is the number of pips from your entry price to the stop loss level.

- Pip value per lot is the value of one pip for the currency pair you are trading.

3. Fixed Amount of Money 

Traders can also choose to risk a fixed amount of money per trade. This could be risking $1,000 every trade despite the changing account balance.  

Lot Size = Money Risked /  (Stop Loss in pips * Pip value per lot)

Manual vs. Automatic Lot Size Calculators

Traders may consider using readily available online lot size calculators or even manually creating an excel formula to crunch these numbers each time you put on a trade.

However, doing so would mean spending precious time as you could miss out on a trade opportunity and cause psychological stress.

There are automated tools like Quantum Keys that can accurately calculate the lot sizes for you.

Some advantages of Quantum Keys:

  • Automatic lot size calculations are super accurate 
  • Eliminates human error 
  • Compatible with MT4 and MT5 
  • Streamline trading process, enter trades as lot size is calculated
  • Protects mental capacity to focus on trading task at hand 


The lot size you opt for depends on whether you're a novice or seasoned trader. Each lot size comes with its own set of advantages and drawbacks, so selecting an appropriate lot size is crucial decision as it impacts your performance and risk management.

Calculating lot size manually may not be ideal when trade opportunities present themselves because of human error and time needed to punch in the numbers. 

If you want to streamline your trading process with automatic lot size calculators and many more features, choose Quantum Keys.

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