How Many Contracts Can You Trade With a Trailing Drawdown? The Position Sizing Math

Updated September 30, 2026

Why account-size risk rules break under a trailing drawdown

Most position sizing advice starts from account size: risk 1% or 2% per trade. In a prop firm evaluation, the account size is mostly irrelevant. What ends the account is the distance between your balance and the trailing floor, and that distance is much smaller.

Take a $50,000 account with a $2,000 trailing drawdown. Risking 1% of the account means $500 per trade. That is a quarter of the real buffer: four full losses in a row and the account is gone. The account-size rule feels conservative, but measured against the buffer it is aggressive.

A trailing drawdown adds a second problem: the buffer is not fixed. When your high-water mark rises, the floor rises with it. Under intraday trailing, even open profit you later give back lifts the floor. (See intraday vs end-of-day trailing drawdown for a worked example.) So the number to size from is the buffer right now, recalculated before every trade.

The math: buffer, floor and risk per contract

Remaining buffer

remaining buffer = current balance − trailing floor

If your balance is $50,800 and the floor has trailed up to $49,300, you have $1,500 of room, even though the drawdown rule says $2,000.

Risk per contract

risk per contract = stop distance in points × dollar value per point

Point values: NQ $20, MNQ $2, ES $50, MES $5. A 20-point NQ stop risks $400 per contract; the same stop on MNQ risks $40.

Maximum contracts

max contracts = floor((remaining buffer × risk share) ÷ risk per contract)

The risk share is the fraction of the buffer you are willing to lose on a single trade. Using 100% means one full loss ends the account. Many traders cap it well below that; the tables below use 50%.

Where the floor sits on the chart

buffer in points = remaining buffer ÷ (dollar value per point × contracts held)

With $2,000 of buffer and 1 NQ contract, the floor is 100 points below the high-water mark. With 2 contracts it is 50 points away. Every contract you add pulls the floor closer.

Position sizing tables for NQ, MNQ, ES and MES

Maximum contracts when risking at most 50% of the remaining buffer on one trade:

A zero means one full-size contract at that stop risks more than half the buffer. That is the point to switch to micros, tighten the stop, or skip the trade. It is also why micros are useful in evaluations: they let you size in steps one tenth as large.

How many losing trades can you absorb?

losses to floor = remaining buffer ÷ risk per trade

Losing streaks of four or five trades are common for most strategies. Sizing so that a normal streak cannot reach the floor matters more than the size of any single winner.

Worked example

You are in a $50,000 evaluation with a $2,000 trailing drawdown. After a few days your balance is $51,000 and the floor has trailed to $49,800, so your remaining buffer is $1,200. You plan an NQ trade with a 15-point stop and cap risk at 50% of the buffer ($600).

• NQ: 15 × $20 = $300 per contract → $600 ÷ $300 = 2 NQ.
• MNQ: 15 × $2 = $30 per contract → $600 ÷ $30 = 20 MNQ, the same risk in smaller steps, so you can scale out.

If the trade loses, the buffer drops to $600, and the next trade's size must shrink with it: at the same stop and cap, $300 ÷ $300 = 1 NQ. Sizing is recalculated every trade, not set once per account.

Pre-trade checklist

1. Know the floor. Write down your current balance and trailing floor before the session. If you don't know the floor, you can't size.
2. Size from the remaining buffer. Apply your risk share to the buffer, not the account, and round down.
3. Fit the stop to the size, not the other way round. If the stop your setup needs makes max contracts zero, use micros or pass.
4. Plan the give-back under intraday trailing. Decide how much open profit you will let a trade return before taking some off, because returned profit still raised the floor.
5. Recalculate after every trade. Wins can raise the floor; losses shrink the buffer. Both change the next size.

Rules differ between firms and between evaluation and funded accounts (for example, where the floor stops trailing, and daily loss limits), so check your firm's current rules page.

Tools that do the math for you

• Trailing Drawdown & Position Sizing Calculator: enter your buffer, stop and instrument to get the floor price and max contracts, with an adjustable risk share.
• TradeGuard Trailing Floor indicator: free and open-source (MIT) for TradingView. It plots the high-water mark and floor on your chart. See how to install it.

FAQ

How do I calculate max contracts with a trailing drawdown?

Multiply the remaining buffer by the share you'll risk on one trade, divide by stop points × dollar value per point, and round down. $2,000 × 50% ÷ (20 × $20) = 2.5, so 2 NQ contracts.

Should I size from my account size or my drawdown?

From the remaining drawdown buffer. On a $50,000 account with a $2,000 trailing drawdown, 1% of the account ($500) is a quarter of the buffer.

Are micro contracts better for trailing drawdown accounts?

They are more flexible. MNQ and MES are one tenth the size of NQ and ES, so they fit small buffers that can't carry a full-size contract at your stop.