How Many Options Contracts Should You Buy?

$20,000 times 2% is $400. That’s the whole method for a long option, and the rest is division.

The mistake is working from the price tag. An option quoted at $1.60 looks cheap, so ten contracts feel like a modest bet at “only” $1,600, which is eight percent of a $20,000 account riding on a position that can be worth nothing at expiration if the stock simply fails to move far enough in time. The premium on a long option is the most you can lose. It’s also, fairly often, the amount you do lose.

How do you work out the number?

Start from the account. Pick the share of it you’ll risk on one idea, and keep it small and fixed; 2% is the example here. Then divide by what one contract costs.

Always round down. Three contracts would put $480 at risk. That breaks the budget you just set.

Notice that the answer doesn’t depend on where you think the stock is going. It depends on the account, the risk share, and the premium. A pricier option gets fewer contracts. A cheap one gets more, and that’s where the discipline pays off, since cheap options are usually cheap because they’re far out of the money or close to expiring, and both make a total loss more likely.

Do you have to plan for a total loss?

For sizing, yes. A mental exit at half the premium is a fine plan. The option can still gap through that level overnight, or lose value faster than you can react in the last days before expiry, and when that happens the exit you planned never gets a fill anywhere near the price you pictured. Size on the full premium. Then the worst outcome is one you agreed to in advance.

To see the position’s value at other stock prices, use the options profit calculator.

What if the budget won’t buy one contract?

Then the answer is zero. On the same $20,000 account, an option quoted at $5.00 costs $500 a contract, and $400 divided by $500 rounds down to nothing. Buying one anyway means risking more than you decided to.

You have honest alternatives. A debit spread, which pairs your long call with a short call at a higher strike, lowers the cost per position and so the amount at risk, in exchange for a capped gain, and it may bring the trade inside the budget. A later or cheaper strike changes the trade itself. Sometimes the right size for the idea is none.

Is one contract always 100 shares?

Usually. A standard equity option covers 100 shares. That’s the multiplier behind every quoted price.

After a stock split, merger, special dividend or spinoff, though, the options exchanges can adjust existing contracts, and an adjusted contract may deliver a different number of shares, or shares plus cash, or shares of two companies. The quoted price then multiplies out differently. A position sized on the usual 100 can turn out to be something else entirely.

Can you actually get out of the position?

Size also has to fit the market for that option. Two numbers tell you.

Open interest is the count of contracts still open at that strike and expiration. Low open interest means few people hold the contract, so fewer are around to trade it with you later.

The bid-ask spread is the cost of a round trip. If the bid is $1.50 and the ask is $1.70, buying at the ask and selling straight back at the bid loses $0.20 a share, $20 a contract, before the stock moves at all. On two contracts that’s $40, a real bite out of a $400 budget, and on a thin option late in the day the spread can be wider still.

A good fit is an order size that’s small next to the open interest, in an option whose spread is a small fraction of its price. If your count fails either test, pick a more active strike or expiration.

What about selling options?

Short options need a different method. The premium you collect tells you almost nothing about what you can lose.

Size a short option by the loss at the point where you’d exit, or, if it’s a spread, by its defined maximum loss. For a short put with no spread, that means picking the price where you’d buy it back and working out the loss there, then asking whether a gap past that price would still be survivable. The same 2% budget can be applied. It just gets divided by a different number.

Very short-dated options raise the stakes. The premium can go to zero within the day. Same-day options reward speed makes the case for sizing them smaller still. For more on building positions, see the options desk.