You can calculate your max daily loss in under a minute, and yet plenty of traders still guess it. Guessing works right up until the day it doesn’t, and then an account that cost real money is gone before lunch.
This guide shows you how to calculate max daily loss for a prop firm account the way a careful trader would: first the formula, then three examples (a fresh account, an account in profit and an account with open trades), then the mistakes that quietly wreck the maths. If you prefer to skip the arithmetic, the free drawdown calculator does every step for you.
The three numbers you need
Before any maths, collect these from your firm’s rulebook and your trading platform:
- The daily loss percentage (for example 5%) or a fixed dollar amount.
- The base the percentage applies to: your initial account size, or your balance or equity at the start of the day.
- Your start-of-day figure, taken at the firm’s reset time.
If any of these is unclear, stop and find out. A wrong input gives a confident but wrong answer, which is worse than no answer.
The core formula
Here it is in plain words, then in symbols.
Max daily loss = base amount × daily loss percentage
Equity floor = start-of-day figure − max daily loss
Room left = current equity − equity floor
That’s all of it. The tricky part isn’t the multiplication, it’s choosing the right base and the right start-of-day figure.
Example 1: a fresh $50,000 account
You buy a $50,000 challenge with a 5% daily limit. It’s day one, so the start-of-day figure equals the account size.
- Max daily loss: $50,000 × 5% = $2,500
- Equity floor: $50,000 − $2,500 = $47,500
If equity ever touches $47,500 today, you’ve breached. Nice and simple. If you risk 0.5% per trade ($250), you could take ten full losses before the wall. That sounds like plenty until you remember how easily a bad hour produces five or six.
Example 2: the same account after a good week
A week later you’re up $2,000. You start the day at $52,000.
If the limit is a percentage of the initial size: max daily loss is still $2,500 and the floor is $52,000 − $2,500 = $49,500.
If the limit is a percentage of start-of-day equity: max daily loss is 5% × $52,000 = $2,600 and the floor is $49,400.
Notice how profit changes both the floor and the room. That’s why people who memorised “2,500” on day one get surprised later. The article on balance-based versus equity-based rules explains how to find which version your firm uses.
Example 3: open trades on the screen
You start at $50,000 again. By mid-morning you’ve closed two trades for a combined loss of $400. You also have one open trade that’s currently $700 against you.
- Closed loss: −$400
- Floating loss: −$700
- Total for the day: −$1,100
- Current equity: $48,900
- Room left: $48,900 − $47,500 = $1,400
You have used 44% of your daily limit, even though you’ve only “lost” $400 on the history tab. This is the hidden trap described in floating losses and open trades.
Fixed-dollar limits
Some firms (futures firms especially) state the daily limit as a dollar figure, like $1,100 on a $50,000 account. In that case you skip the percentage step: max daily loss is simply that number. If you want to use a percentage-based tool, divide the dollar limit by the account size. $1,100 ÷ $50,000 = 2.2%.
Turn it into trades
A floor is useful, but a plan is better. Divide your room left by your risk per trade.
With $1,400 left and $250 risk per trade, you can absorb five full losses. Add a safety margin and the number drops. Using a soft stop at 80% of the limit, you’d stop at $48,000 equity, which leaves $900 of usable room and three trades. That figure is much more honest about how many bullets you really have.
Add a safety margin on purpose
The firm’s number is the edge of the cliff. Real trading involves slippage, spreads that widen without warning and fills at prices you didn’t choose. So leave a buffer. A common approach is to treat 60% to 80% of the limit as your own daily stop. We cover how to choose yours in setting a personal daily stop.
Mistakes that wreck the calculation
Using the wrong base
Initial size versus start-of-day equity. Check the rulebook, and if it’s vague, email support and keep the answer.
Using the wrong start time
If the firm resets at a certain server time, your “start-of-day” figure is the equity at that moment, not at midnight local time. See the reset time guide.
Forgetting costs
Commissions and swaps change your equity. Some firms count them in the daily loss. Details are in do swaps and commissions count toward daily drawdown.
Ignoring open risk
Three open trades risking 0.5% each are 1.5% of the account at risk, all at once. Add them up before you click.
Rounding in your favour
Round the floor up and the room down. If your platform shows $47,512 and the floor is $47,500, you’ve got $12, not “plenty”.
Calculate it in a spreadsheet
If you like having your own sheet, you only need five cells: account size, percentage, start-of-day equity, current equity and risk per trade. Then three formulas: max loss, floor and room left. Add a conditional format that turns the room cell red under 20% of the limit. It takes five minutes to build, and a tracking service like Myfxbook can supply the live equity figure if you’d rather not type it.
A five-step checklist
- Find the daily percentage and base in the rulebook.
- Record your start-of-day equity at the reset time.
- Multiply to get the max daily loss.
- Subtract to get the equity floor and write it down.
- Check the room left before every trade.
Quick reference: common account sizes at 5%
If you only want a ballpark, this table shows the daily room for popular sizes at a 5% limit calculated on the initial balance. Replace the percentage with your own.
| Account size | Max daily loss (5%) | Floor at start | Room at 0.5% risk per trade |
|---|---|---|---|
| $10,000 | $500 | $9,500 | 10 losses |
| $25,000 | $1,250 | $23,750 | 10 losses |
| $50,000 | $2,500 | $47,500 | 10 losses |
| $100,000 | $5,000 | $95,000 | 10 losses |
| $200,000 | $10,000 | $190,000 | 10 losses |
Notice that the number of losses you can absorb is the same on every row. That’s the point: risk per trade as a percentage scales with the account, so your room measured in trades stays constant. What changes is the dollar size of each loss, and with it, how emotional a bad day feels.
What if you’ve already lost money today?
This is the situation the calculator is really built for. Say you start at $100,000 with a floor of $95,000. By 11 a.m. you’re down $2,300. Your current equity is $97,700 and your room left is $2,700, not $5,000.
Now your risk per trade should be judged against $2,700, not against the whole day’s allowance. If you risk $500, you have five trades left in theory and three or four in practice. Many traders keep sizing as though the day had just begun, which is how a normal losing morning becomes a breach.
Working with more than one account
If you run several challenges at once, calculate each separately and write the floors side by side. Never assume the same trades on different accounts produce the same percentage result, because lot sizes, spreads and base amounts can differ. And if you copy trades across accounts, remember that a single bad idea now loses on every account at the same moment.
Percentages or dollars in your notes?
Both help. Dollars keep you honest about what’s at stake. Percentages let you compare days across different account sizes. In your trading journal, record the percentage of the daily limit used at the end of each day. If that number is often above 50%, your risk per trade is probably too high.
Decimals, rounding and costs
Small things add up. A $12 commission on a standard lot, a swap charge at rollover and a two-pip spread on entry can take $40 of room from a trade you thought risked $250. Over ten trades, that’s $400, which is nearly a full trade’s worth of room. When you set your risk, build in a cost allowance of about 5% to 10% of the planned risk.
A pre-session worksheet you can copy
- Account size: ______
- Daily limit % and base: ______
- Start-of-day equity (at reset time): ______
- Max daily loss: ______
- Equity floor: ______
- Personal stop (60% to 80% of the limit): ______
- Risk per trade: ______
- Maximum trades today: ______
Fill it in with a pen, not on a screen. It sounds silly, but the physical act slows you down enough to notice when a number looks wrong.
Cheat sheet: the formulas in one place
- Max daily loss = base × percentage (or the fixed dollar figure).
- Equity floor = start-of-day figure − max daily loss.
- Current equity = start-of-day figure + today’s profit or loss (closed and floating).
- Room left = current equity − floor.
- Used percentage = (start-of-day figure − current equity) ÷ max daily loss × 100.
- Trades you can absorb = room left ÷ risk per trade, rounded down.
A three-day view
It helps to see how the numbers move over a few days. Take a $50,000 account with a 5% limit applied to start-of-day equity.
| Day | Start equity | Max daily loss | Floor | Result |
|---|---|---|---|---|
| Mon | $50,000 | $2,500 | $47,500 | +$600 |
| Tue | $50,600 | $2,530 | $48,070 | −$1,400 |
| Wed | $49,200 | $2,460 | $46,740 | +$300 |
The floor changes every day because the starting point changes. A trader who memorised “$47,500” on Monday would have used the wrong number on Tuesday and Wednesday. Make the calculation part of your morning, not a one-off.
Special cases: weekends, holidays and gaps
Markets don’t always behave like a tidy Monday-to-Friday spreadsheet. If you hold a trade over the weekend and the market gaps on Sunday night, the loss can arrive in a single tick and count towards whichever “day” the firm assigns to it. Some firms count it in Monday’s daily loss, so you might begin the week already partly used up.
Bank holidays can also shift the reset time or thin out liquidity, which widens spreads. On those days it’s worth lowering size, or simply sitting out, rather than trusting the usual numbers. A good rule: if the day feels unusual, assume the room is smaller than the calculator says.
One last sanity check
Before you trust any number, compare it with the firm’s own dashboard. Most dashboards show a “max daily loss” or “daily drawdown” figure. If your result and theirs differ by more than a few dollars, find out why before you place a trade. Usually it’s the base amount, the reset time or a cost you forgot. A two-minute check on day one saves a lot of regret later, and it builds the habit of treating the firm’s number as the official one.
Frequently asked questions
Is the daily loss based on balance or equity?
It depends on the firm. Equity-based is stricter because it includes floating profit and loss. If you don’t know, assume equity.
Does the limit change when I’m in profit?
It can. If the percentage applies to start-of-day equity, the dollar figure grows with profit. If it applies to the initial size, it stays fixed.
Do I use my account currency?
Yes. Work in the account’s own currency so all your numbers line up with the firm’s dashboard.
Can I trust my broker’s equity number?
Mostly, but the firm’s own dashboard is the final authority. Compare the two now and then, especially around rollover.
Wrapping up
To calculate max daily loss, multiply the correct base by the daily percentage, subtract it from your start-of-day figure and compare it with your current equity. Then leave yourself a margin. If you want to understand the rule behind the numbers, start with the prop firm max daily drawdown explained, and when you’re ready to size trades, move on to position sizing for prop firm challenges. Both the Investopedia position sizing page and your firm’s own FAQ are worth a read too.