# How Much Buying Power Do Options Use? Margin for Sellers Source: https://theoptionsbench.com/guides/how-much-buying-power-do-options-use/ > Plain-text mirror for AI/LLM ingestion. Canonical HTML page: https://theoptionsbench.com/guides/how-much-buying-power-do-options-use/ --- The same options trade can tie up the full strike price or just a few hundred dollars - it depends on the structure you sell and the account you sell it in. A Cash-Secured Put reserves the **full strike price x 100**. The same Put sold naked on a margin account reserves a **fraction** of that. A defined-risk spread reserves **least of all**. And a portfolio-margin or SPAN account can cut the number again. Same trade, very different capital. Here is each one, with one real example priced every way. ## What "buying power" actually means Buying power is the cash your broker lets you put to work. **Buying-power reduction (BPR)** is how much a single trade ties up while it is open. For an option Seller, BPR is the collateral the broker holds in case the trade goes against you - it is *not* what you paid, and it is often *not* your maximum loss. Read it wrong and you over-leverage without noticing; read it right and you can size positions properly. ## A Cash-Secured Put: the full amount A Cash-Secured Put is "secured" because you set aside the entire cash to buy the shares if you are assigned: > Buying power = strike price x 100 (per contract) Sell one $295-strike Put and the broker holds **$29,500**. You collect the premium up front, so your real outlay is a little less, but the full amount is reserved against assignment. This is the most conservative way to sell a Put, and the figure the [Cash-Secured Put Calculator](/cash-secured-put-calculator/) shows as "cash secured / margin required." ## A naked Put on margin: a fraction of that Sell the same Put *without* setting the cash aside - a naked Put in a margin account - and the requirement drops sharply. A common Reg-T formula, per share, is: > premium + the greater of: (20% of the stock price - the out-of-the-money amount) or (10% of the strike) On a $310 stock with that $295 Put, that is the greater of (20% x 310 - 15) = 47 or (10% x 295) = 29.50, so about **$47 x 100 = $4,700** of buying power instead of $29,500. The catch: the **dollar risk is identical**. If the stock collapses you lose the same money - you have just put up one-sixth the collateral, which is leverage. And if the Put is assigned you still have to take the shares, which on margin becomes a roughly 50% requirement or a margin loan, so a small naked position can balloon fast. Brokers also add minimums and charge more on volatile or earnings-week names, so treat the formula as a guide, not a quote. ## A Covered Call: the shares are the collateral A Covered Call sells one Call against **100 shares you already own**, so the shares themselves are the collateral and the short Call adds **no extra margin** - it is covered. The buying power tied up is just the cost of those shares (or their margin requirement if you hold them on margin). By put-call parity a Covered Call and a Cash-Secured Put at the same strike have the same payoff, which is why they need about the same capital. The [Covered Call Calculator](/covered-call-calculator/) models the income and the capped upside. ## Defined-risk spreads: the least buying power This is where the requirement falls off a cliff. A credit spread - say a Bull Put Spread - buys a protective long Put below the one you sell, so the broker reserves only the worst case: > Buying power = (strike width - net credit) x 100 (per contract) Sell the $295 Put and buy the $290 Put for a $1.50 net credit and the most you can lose - and the most that is reserved - is (5 - 1.50) x 100 = **$350**. The same bullish-income view that tied up $29,500 as a Cash-Secured Put now uses a few hundred dollars *and* caps the loss. The [Bull Put Spread Calculator](/bull-put-spread-calculator/) returns the exact buying power at risk. You give up a larger premium for a hard floor under the loss. ## The same trade, priced every way One contract, bullish on a $310 stock, sold at the $295 strike: - **Cash-Secured Put:** about **$29,500** of buying power. - **Naked Put (Reg-T margin):** about **$4,700**. - **Bull Put Spread ($295 / $290):** about **$350**. The cash-secured and naked Puts carry the *same* downside - only the collateral differs. The spread is the one that actually changes the risk, because the long Put caps it. ## Why your broker's number is different The formulas above are the standard **Reg-T** rules, and your platform will rarely match them to the dollar. Brokers add house minimums, raise requirements on volatile names and through earnings, and treat each account type differently: - **Cash account:** you must fully secure the trade - the cash-secured figure. - **Reg-T margin:** the rule-based formulas above, naked positions allowed. - **Portfolio margin:** risk-based - it stress-tests your whole book and can require much less on hedged positions (and more on concentrated ones). - **SPAN:** the risk-based system for futures and options on futures, again often lower for offsetting positions. Always read the buying-power reduction your platform shows on the order ticket before you commit - that, not a formula, is what your account will actually hold. ## Buying power is not risk This is the one to internalise. The naked Put above uses roughly one-sixth the buying power of the cash-secured version, but it loses the **same dollars** if the stock falls to zero. Low margin makes return-on-capital *look* spectacular precisely because the denominator shrank - the risk did not. Size every position by the loss it can hand you, not by the buying power it frees up. The [Kelly Criterion Position Sizing](/position-sizing/) tool turns your edge and account size into a sensible position, and the [position-sizing guide](/guides/position-sizing-options-trading/) covers the rule of thumb most sellers actually use. ## How to free up buying power If you are capital-constrained, the honest lever is **structure**, not leverage: - **Trade defined-risk spreads** instead of naked or cash-secured Puts - the single biggest reduction, and it caps the loss too. - **Use a lower-priced underlying** so each contract reserves less. - **Close or roll** positions that have done their work rather than letting them tie up collateral to the last day. What you should *not* do is free up buying power by going naked and then sizing as if the risk shrank with the margin. It did not. The cheapest honest way to sell premium with a small account is a defined-risk spread; the cash-secured route asks for far more capital but hands you a larger premium and, if assigned, a stock you were willing to own. For the full picture on starting capital, see [how much money you need to sell options](/guides/how-much-money-to-sell-options/).