Prop Sizing Lot Size Calculator

💭 DOES THIS SOUND FAMILIAR?

• Do you find the lot calculation slow and boring?
• Does it get worse with every new currency pair?
• Are you afraid of hitting a loss limit and losing the account?
• Does every lost account hurt more than the last one?

I was caught in this loop myself. I built this tool for my own use.

📌 WHAT THIS IS

This is an indicator. It contains no order functions at all.
It cannot open, modify or close a position.

Drag the stop-loss line on your chart and the lot size is calculated from your account balance and the loss limits your firm gives you.

✅ WHAT IT DOES

• Drag the stop-loss line and the lot size updates at once.
• Direction is read from the line.
  Below the price is BUY. Above the price is SELL. The panel shows which one.
• Optional TP preview line. It is off by default.
  Turn on "Show the TP preview line" and it is placed from your Risk-Reward setting and follows the stop-loss line as you drag it.
• The risk is shown in your account currency, not only in percent.
• Available shows how much of your allowed loss is still left, in your account currency.
• Round-trip commission for the current lot is shown next to the lot size.
  It is measured from your own trade history, or taken from your input if there is no history.
  It is shown for reference and is not included in the risk amount.
• Spread guard.
  The panel warns you when the stop-loss line is inside the spread and the direction cannot be decided.
  It also warns you when the spread is wider than your Maximum spread setting.
• Entry Count from 1 to 10 for split entries. Lot and risk are shown for one entry.
  An "x2", "x3" ... mark appears next to the risk, so a split entry cannot be misread.
• Fixed lot mode when you do not want the calculation.
• Entry Count and the stop-loss line are stored per chart.
  They stay after a timeframe change and a restart.
• The panel can be collapsed to its title bar.
• I use it live on FX majors and crosses.
  It has also been checked on gold (XAUUSD), BTCUSD and indices such as US30. Brokers set symbols differently, so check with a small lot first.

🧪 HOW THE LOT IS CALCULATED

The tool works in four steps.

1. Available. How much you can still lose.
It comes from your Initial Balance, Maximum Overall Loss (%) and Maximum Daily Loss (%).
The limit you would hit first is used.

2. Divide by Maximum allowed losses. This is how many losing trades in a row you want to survive.

3. Cap the risk. Maximum Risk per Trade (%) of your Initial Balance is the most one trade can risk, so the risk stays the same from trade to trade.
Set it to 0 to turn the cap off.

4. Work back from the stop. The distance to your stop-loss line is turned into a lot size for the current symbol.

You enter the limits your firm gives you. The tool does the rest.

🔧 SETTINGS

Example: a 50,000 account with a 10% overall loss limit and a 5% daily loss limit.

• Fixed lot size: 0.0
  0 means the lot is calculated for you.
  Enter a lot size only if you want a fixed lot instead.
• Initial Balance: 50000.0
  The starting balance of the account, in your account currency.
  Set 0 to use your current balance instead.
• Maximum Overall Loss(%): 10.0
  The overall loss limit, in percent of Initial Balance.
• Maximum Daily Loss(%): 5.0
  The daily loss limit, in percent.
  It is measured from the balance at the start of the day.
• Maximum Risk per Trade: 0.0
  A cap on the risk of one entry, in percent of Initial Balance.
  0 turns the cap off.
  If your firm limits the risk of a single trade, entering about half of its limit leaves a margin.
• Maximum allowed losses: 10
  How many losing trades in a row you want to survive.
• Entry Count: 1
  How many split entries you plan, from 1 to 10. It is not part of the lot calculation.
  With Maximum allowed losses 10 and Entry Count 2, the number of losing trades you survive is 5 (10 / 2).
• Default SL(point): 0.0
  The starting distance of the stop-loss line, in points.
  0 places the line at half the range of the last 20 bars.
• Symbol Suffix: empty
  The ending your broker adds to symbol names, such as .m.
  Leave it empty if there is none.
  It is used to find the currency pair that converts the risk into your account currency.
  If that pair cannot be found, the panel shows Rate error.
• Maximum spread: 50.0
  The spread limit, in points (50.0 is 5 pips on a 5-digit symbol).
  The panel warns you in red when the spread is wider. 0 turns the warning off.
• Round-trip commission per 1.00 lot: 0.0
  Used only when there is no trade history to measure from.
  It is shown for reference and is not included in the risk amount.
• Show the TP preview line: false
  Turn it on to draw a TP preview line. It only draws a line.
  This indicator places no orders.
• Risk:Reward: 1.0
  The TP distance as a multiple of the stop-loss distance.
  1.0 puts the TP as far from the entry as the stop loss.

In this example, on a day that starts with a balance of 50,000, Available is 2500.00, because the 5% daily limit is reached before the 10% overall limit.
The risk of one entry is 250.00 (2500.00 / 10).

⚠️ IMPORTANT

• When DefaultSL is 0, which is the default, the first stop-loss line is placed below the current price, at half the range of the last 20 bars of the timeframe you are on.
  Because the distance comes from the range, it may be an odd number such as 119 pips, and it changes when you switch timeframe.
  This is intended.
  Set DefaultSL to a fixed value if you want the same starting distance every time.
• This indicator and the EA versions cannot run on the same chart.
  If Prop Sizing Trade Panel and Lot Calculator or Prop Sizing Trade Copier EA is attached to the same chart, the EA will notify you and remove this indicator.
  The stop-loss line position is not carried over. This is by design.
• The older free Prop Sizing EA does not have this detection.
  Do not run it on the same chart as this indicator.

📋 ABOUT PROP FIRM RULES

Prop firms have different rules about third-party tools.
Some do not allow Expert Advisors that you did not write yourself.
Some also restrict third-party indicators, even ones that only calculate the lot size.
Rules can change. Check the rules of your own firm before you use this product.
Whether to use it is your decision.

🎯 ONE THING ONLY

This tool does one thing. It shows the lot size that lets you survive a losing streak, and nothing else.

🔗 ALSO AVAILABLE

• Prop Sizing Trade Panel and Lot Calculator - the same calculation, with one-click ordering from the panel.
  MetaTrader 5.
• Prop Sizing Trade Copier EA - the same, plus copying to your other accounts on the same PC. MetaTrader 5.
• Prop Sizing Lot Size Calculator MT4 - this same indicator for MetaTrader 4. Free.