Buying Power Calculator - Margin and Cash Capacity

Buying Power Calculator is designed for brokerage margin capacity checks, where a small change in one input can alter a decision, budget, or performance story. The calculator keeps the assumptions visible beside the result so the number can be reviewed instead of copied blindly. Use the fields as a compact worksheet: enter the values using the units shown on each label, calculate the primary result, then read the supporting lines to understand which driver is moving the answer. The calculation multiplies cash by the allowed margin factor and subtracts capital already committed to positions plus required reserve. In plain terms, Available buying power = cash balance x margin multiplier - open positions - maintenance reserve. The supporting outputs are included because the headline number rarely gives enough context on its own. Margins, rates, totals, variances, or remaining balances explain whether the result is caused by price, volume, time, cost structure, or exposure. Common use cases include checking available capital before a trade, comparing cash and margin accounts, sizing position limits, and leaving room for maintenance requirements or risk controls. A practical review usually compares at least three cases: conservative, likely, and optimistic. Change one input at a time so the sensitivity is clear; if a small input movement creates a large output change, document the assumption and look for a better source before presenting the result. Important caveats include broker-specific margin rules, pattern day trader limits, concentration charges, unsettled cash, short-sale requirements, options approval, and intraday risk adjustments. The calculator is a deterministic planning aid, not a substitute for professional advice, policy review, tax guidance, legal review, HR judgment, brokerage instructions, or a full financial model. Rounding can also matter when the result will be used in contracts, accounting entries, payroll conversations, or regulated decisions. For best results, keep time periods and units consistent. Enter percentages as ordinary percentage values, such as 8 for 8%, rather than decimals. Available buying power can be negative when existing positions and reserves exceed the capacity implied by cash and the multiplier. After calculating, compare the answer with an independent estimate or source document and save the assumptions that support the scenario.