A provider's one-lot position is not automatically appropriate for every follower. Proportional copy sizing converts source activity into a volume that reflects the follower account and selected settings. The objective is scaling, not exact duplication.
The basic sizing relationship
A simple conceptual model compares the funds assigned to copying with the provider's available funds, then applies the resulting ratio to the provider volume. Real platforms can also consider leverage, currency conversion, product specifications, minimum volume and permitted volume steps.
An illustrative example
Suppose a provider uses 10,000 of available funds and opens 1.00 lot. A follower assigns 2,000 under an otherwise comparable setup. A simple proportional result would begin near 0.20 lot. This is an illustration, not a RockCopy formula or a prediction of the executed amount.
Allocation and copy scale
Allocation determines how much of the follower account is designated for the relationship. A separate copy-scale setting may increase or reduce the calculated volume where supported. Both affect exposure, and neither should be treated as a performance target.
Review Copy-Trading Allocation and Stop Controls before setting the amount available to a provider.
Leverage and contract rules
If provider and follower leverage differ, the same nominal position can require a different share of available margin. Contract size, quote currency and margin method can also vary between symbols or account types. A platform may reduce, round or reject an instruction that does not fit the follower account.
Check the exact instrument specification and account terms. Do not infer compatibility from a similar product name alone.
Minimum volume and rounding
Why small instructions change
Tradable volume is discrete. If a product has a 0.01-lot minimum and 0.01 step, a calculated 0.006 lot cannot be sent exactly. Depending on the service rules, it may be rounded, increased to the minimum or skipped. Repeated rounding can make the follower's exposure diverge from the theoretical ratio.
Why results still differ
Even when volumes are proportional, provider and follower prices can differ. Latency, liquidity, price tolerance, spread, commission, financing and account currency affect the outcome. Copy-Trading Execution Gaps, Price Tolerance and Latency explains these differences.
Changes that require rechecking
Deposits, withdrawals, realised profit or loss, provider fund changes and a new allocation can alter the ratio. A provider can also change instruments or trading style. Review the copied size after any material change rather than assuming the original relationship remains stable.
A sizing checklist
- Confirm the funds allocated to copying.
- Understand the current scale or ratio setting.
- Compare provider and follower leverage.
- Check contract size, minimum volume and volume step.
- Estimate margin under a stressed scenario.
- Observe the first copied instructions and explain any rounding.
- Recheck after cash or setting changes.
Smaller sizing can reduce the amount exposed, but no ratio removes market, leverage or execution risk. Use a size that the follower account can sustain without relying on uninterrupted copying or immediate closure.