Account sizes here run $2.5K–$200K, and the reflex is to buy near the top of what the budget allows. The reasoning is intuitive — a bigger account pays more per percent, the fee is a one-off, and if you are good enough to pass a small one you are good enough to pass a large one.
The first two are true. The third is where it goes wrong.
Size changes behaviour, not just arithmetic
Percentage rules scale cleanly. A 4% daily loss limit is 4% whether the account is $10,000 or $400,000. What does not scale cleanly is you.
A $400 loss and a $16,000 loss are the same trade in percentage terms and are absolutely not the same experience. The second one produces hesitation on the next entry, and hesitation on the next entry is how a working strategy stops working. People do not usually fail large accounts by making worse decisions in the abstract; they fail them by making the same decisions late, small, or not at all.
A working strategy stops working the moment you hesitate on the entries. Size is the most common cause of hesitation.
A test worth running before you buy
Take the daily loss limit on the size you are considering and write it out in your own currency, as a plain number. Then take your worst historical day, expressed as a percentage, and apply it to the same account.
If the number makes you flinch, the account is too big. Not too expensive: too big. Those are different failures and only one of them is fixed by having more money.
The scaling argument
There is also a structural reason not to start at your ceiling. The account is not fixed — on the CFD line it grows through the scaling ladder to twice its starting size as you clear milestones, while the split stays the one your plan states. Starting smaller and scaling arrives at a large account on better terms than buying the large account outright.
It is slower. It is also the route that does not require you to be immediately excellent at a size you have never traded.
When a bigger account is right
- You have traded the strategy at comparable size before, with your own money or a previous funded account, and have the record to show it.
- Your edge needs the room — some strategies genuinely cannot express themselves inside a small account's position limits, and shrinking them changes what you are testing.
- The fee is genuinely immaterial to you, so a failed attempt costs you an afternoon rather than a month's savings, and will not colour the next attempt.
Outside those three, start below your ceiling. The account is not the prize; the payout record is, and that is built at any size.