Understand your isolated margin model

1. Define the units and count each cost once

Select the own isolated linear variant and long or short explicitly. Enter a positive underlying quantity q and a positive entry price E per unit. Choose CZK, EUR or USD as the common quote currency. Quantity is not a contract count with an inferred multiplier. All collateral and reserve amounts must already use that currency; the label performs no conversion. The variable P is a hypothetical positive valuation price, not a fetched market observation, executable quote or exchange mark price.

Collateral C is nonnegative and is supplied BEFORE the separately entered fixed cost reserve R. That reserve has not already been deducted: the model subtracts it once. Supply your constant maintenance percentage m and, if known, closing-fee percentage f. They apply to q times P in this chosen model. Enter percentages as percentage units, not fractions; the calculation divides by 100. Each rate is below 100 and a known sum m+f must also be below 100.

Blank closing fee or reserve means unknown. An explicit 0 is a known zero assumption. Missing costs leave the complete entry buffer and boundary unavailable; they do not become zero even when another metric is zero. Independently known entry notional qE can still be shown. These are your supplied assumptions, not verified account balances, tariff rules or accrued funding charges.

2. Read the equation and its distinct states

For long, model equity is C−R+q(P−E); for short it is C−R+q(E−P). The model requirement is qP(m+f), with m and f now fractions. At entry, compare C−R with qE(m+f). A negative buffer means the requirement is already unmet at your entry assumption. An exact zero is an at-entry model boundary. Neither state establishes an actual margin call, forced close or permission to open.

With a positive entry buffer and known costs, equality gives long P=(qE+R−C)/(q(1−m−f)), or short P=(C+qE−R)/(q(1+m+f)). Read the numerator and denominator separately. A valid long numerator at or below zero produces no positive crossing in the chosen P>0 domain. Its boundary stays null, rather than a fabricated zero price. This result does not guarantee that a real position is safe.

Finite products, cash differences and rate fractions use bounded exact arithmetic. Only the final ratio uses 384 significant working digits with HALF_EVEN rounding and is labelled approximate. The raw boundary string is a finite working result, not infinite real-number precision. A numerical budget refusal returns no partial boundary. All displayed components belong to one immutable result with the original entered strings.

3. Recalculate deliberately and keep real venue rules separate

CME material on futures margins and Bybit material on margin modes and liquidation explain concepts and omitted scope; they do not certify these independently chosen equations. Actual products can involve initial-margin admission, maintenance tiers, mark-price rules, cross or inverse contracts, funding, collateral haircuts, insurance and liquidation procedures. This model supplies none of those rules or current values. It is authored application help for the internal pilot, not editorial approval, a venue calculation or a trading recommendation.