The case for starting small
Your first evaluation at any firm is an experiment: can you trade inside these specific rules on this specific platform. That experiment produces the same information whether the account is $10,000 or $200,000, and one costs a fraction of the other.
Traders who start large are paying a premium for information they could have bought cheaply, and they usually pay it more than once.
What is genuinely harder on a small account
Minimum position size. On a $10,000 account with a 3% daily limit you have $300. If the smallest tradeable size in your instrument risks $150 at your normal stop distance, you are risking half the daily limit on one trade whether you like it or not.
This is the real constraint on small accounts and it is worth checking before buying. For forex, micro lots usually solve it. For futures, a single contract on a large-tick instrument may simply be too big for a small account, which is why futures firms often start their evaluations at sizes that accommodate one contract.
Commissions. A fixed per-lot or per-contract cost is a larger share of a small target. A $1,000 target on a $10,000 account with $7 round-turn commissions and 100 trades is $700 of costs against $1,000 of required profit. That changes the arithmetic materially.
Granularity. Fewer size increments means less precise risk. You round up or down, and rounding up repeatedly is how small accounts breach.
What is easier
Everything psychological. The consequences are proportionally identical but emotionally much smaller, which means you are more likely to trade your actual strategy rather than a nervous version of it. For a first evaluation that is worth a great deal.
Choosing the size
Work backwards from the minimum tradeable position. Take the smallest size you can trade, multiply by your typical stop distance, and check that the result is at most 1% of the distance to the breach level. If it is more, the account is too small for your strategy and the next size up is the right choice.
The position size calculator does this in both directions.
Scaling up afterwards
Pass on a small account and you have two routes: buy a larger evaluation with the knowledge you now have, or use the firm's scaling plan to grow the account you already hold.
Scaling is usually the better route, because it grows the account on the strength of results rather than on another fee. But it is slower, and firms differ substantially in how the plan works — which is worth reading before you pick the firm.