Covered Call Calculator

A covered call calculator works out the premium received, maximum profit, break-even price, and potential return for selling a call option against shares you already own. It is used by equity investors seeking to generate additional income from their holdings and by traders willing to cap their upside in exchange for immediate premium income.

How to Use the Covered Call Calculator

1. Enter the current stock price.
2. Enter the call option's strike price.
3. Enter the premium received per share for selling the call.
4. Enter the number of contracts (each contract typically covers 100 shares).
5. Enter the original purchase price of the shares (your cost basis).
6. Click calculate to see the maximum profit, break-even price, and annualised return.

The Formula

Premium received = Premium per share x 100 x Number of contracts

Maximum profit = (Strike price - Share cost basis + Premium per share) x 100 x Number of contracts

Break-even price = Share cost basis - Premium per share

Maximum loss = (Share cost basis - Premium per share) x 100 x Number of contracts (This occurs if the stock falls to zero; the premium received partially offsets the loss)

Return if called away = (Strike price - Cost basis + Premium) / Cost basis x 100

Annualised return if called = Return if called x (365 / Days to expiry)

Real-World Example

You own 100 shares of Company X, purchased at £42 per share. The stock now trades at £48. You sell 1 call option with a £50 strike, expiring in 45 days, for a premium of £1.50 per share.

• Premium received: £1.50 x 100 = £150
• Break-even price: £42 - £1.50 = £40.50 (your effective cost basis, reduced by the premium)
• Maximum profit: (£50 - £42 + £1.50) x 100 = £950 (if assigned at £50)
• Return if called away: £950 / £4,200 = 22.6%
• Annualised return if called: 22.6% x (365/45) = approximately 183%

If the stock stays below £50 at expiry, the option expires worthless. You keep the £150 premium and still own your shares. You can then sell another covered call next month.

Managing a Covered Call Position

The core decision after selling a covered call is what to do as expiry approaches. If the stock is well below the strike price, the option will likely expire worthless and you keep the premium. You then assess whether to sell another call for the next period. If the stock rises above the strike, you face a choice: allow assignment (sell your shares at the strike price and collect the premium), or buy back the call option at a loss (if the cost of buying it back is less than the loss you would take on missing further appreciation) and continue holding the shares. Rolling a covered call involves buying back the expiring call and simultaneously selling a new call with a later expiry and potentially a higher strike, capturing additional time premium while extending your income generation. Covered calls are most effective in sideways to mildly rising markets; in strongly rising markets, the cap on upside is the primary cost of the strategy.

Frequently Asked Questions

What happens if my stock is called away? If the stock price is above the strike price at expiry, the call buyer exercises the option and you must sell your shares at the strike price. This is called assignment. Your profit is capped at the strike price plus premium received, minus your original cost. You no longer own the shares and miss any further appreciation above the strike. To avoid this, you can buy back the call before expiry (at a cost if it is in the money) or roll the position to a later expiry at a higher strike.

Which strike price should I choose? Out-of-the-money strikes (above the current price) collect less premium but allow more upside before assignment. At-the-money or in-the-money strikes collect more premium but have a higher chance of your shares being called away. Most investors using covered calls for income select strikes 5 to 10% out of the money, targeting a balance between premium collected and upside participation. The ideal strike depends on your view of the stock and your willingness to sell at that price.

Is selling covered calls risky? Covered calls are considered one of the more conservative options strategies because the downside is the same as simply holding the shares. The premium received reduces your effective cost basis and provides a buffer against modest price declines. The strategy's risk is opportunity risk: if the stock surges, your gains are capped at the strike price, and you may regret having capped the upside. Selling covered calls on shares you do not own (naked calls) is far riskier and is a different strategy entirely.

What tax treatment applies to covered call premiums in the UK? In the UK, premiums received from writing covered call options are generally taxed as capital gains rather than income. The premium is treated as a capital receipt and pooled with the shares for capital gains purposes. If the option expires worthless, the premium is a capital gain in the tax year of expiry. If the shares are called away, the premium increases the effective disposal proceeds. HMRC's guidance on derivatives and shares is complex; a tax adviser should be consulted for specific positions.

Also try these free tools:

• Cash-Secured Put Calculator
• Black-Scholes Calculator
• Options Greeks Calculator

A second position with two contracts

The first example covers one contract on a hundred shares. A larger position behaves identically per share, and the arithmetic is worth repeating because the annualised figure moves sharply with the time to expiry.

An investor owns 200 shares bought at 18.40 pounds, a total cost of 3,680 pounds. The shares now trade at 22.10 pounds. The investor writes two call options with a strike of 24.00 pounds expiring in 60 days, and receives 0.85 pounds per share.

• Premium received: 0.85 times 100 times 2 = 170 pounds.
• Break-even price: 18.40 minus 0.85 = 17.55 pounds, the cost basis reduced by the premium.
• Maximum profit: (24.00 minus 18.40 plus 0.85) times 100 times 2 = 6.45 times 200 = 1,290 pounds.
• Return if called away: 1,290 divided by 3,680 = 35.05 percent.
• Annualised return if called: 35.05 times 365 divided by 60 = 213.25 percent.

The 213 percent figure deserves a caveat before it is quoted anywhere. It annualises a single 60-day trade as though the same premium, the same capital and the same conditions could be repeated six times over a year. That is a rate of return on the trade, not a forecast, and the second half of the year rarely offers the same entry.

Profit and loss across a range of expiry prices

The payoff of a covered call is capped, and the cap is the whole point of the strategy. The table holds the second example constant and moves only the share price at expiry. Shares are delivered at the strike if the price finishes above it.

Two rows carry the lesson. At 18.00 pounds the position is still profitable even though the shares have fallen from the 18.40 pound purchase price, because the 170 pound premium covers the shortfall. At 26.00 pounds the profit is the same as at 24.00 pounds: the extra two pounds per share, 400 pounds in total, goes to the option holder. That forgone 400 pounds is the price of the premium, and it is only visible if the payoff is written out across a range rather than at a single point.

What the premium is worth in different markets

The same position has a very different return if the option premium is different. Holding the second example constant and changing only the premium shows how much of the result comes from the option price rather than the share price.

The return if called moves by less than four points across the range, because the premium is a small part of a profit that is dominated by the rise from the cost basis to the strike. The return in a flat market moves by more than a factor of two, because the premium is the entire profit when the share price does not move. An investor writing calls for income should read the fourth column, not the third.

Choosing a strike, and what the choice costs

Strike selection trades a higher maximum return against a lower return in a flat market. The premiums in the table below are illustrative, chosen to show the mechanism rather than to quote any market, and they sit on the same 200-share position bought at 18.40 pounds with the share price at 22.10 pounds and 60 days to expiry.

A further strike raises the profit if the shares are called away and cuts the income if they are not. The two columns move in opposite directions, which is why the choice depends on whether the investor expects the shares to be taken or to stay. What the table cannot show is the probability of assignment, and that probability is exactly what the market prices into the premium. A strike far above the current price pays little because it is unlikely to be reached, and the annualised return in the last column is the compensation for that lower probability.

How the figures are built

Five conditions sit behind every figure on this page.

• Each contract covers 100 shares, and the position is fully covered. The strategy carries the same downside as holding the shares, with the premium as a partial buffer, and it carries no exposure to unlimited loss.
• The expiry payoff is settled at intrinsic value. If the share price finishes above the strike, the shares are delivered at the strike and the premium is kept.
• No dividend falls due on the shares during the life of the option. A dividend before expiry can make early exercise worthwhile for a call holder on an American-style contract, which changes the timing of the whole position.
• Commissions, stamp duty and the bid-ask spread are excluded. They reduce the figures, and on a 170 pound premium a round trip in and out plus half a penny of spread can remove several pounds before the trade is closed.
• The annualised figures scale a single trade to a full year. They are rates, not forecasts. 365 divided by 60 is about 6.08, which is the multiplier applied to the 60-day return.

One further convention keeps the break-even meaningful. The break-even price is the cost basis minus the premium per share, and it is the price at which the position neither gains nor loses if the option expires worthless. It is not the price at which the shares were bought, and treating the two as the same understates the protection the premium provides.

Reading the payoff as two positions

The payoff diagram of a covered call is the sum of two positions: a long holding of the underlying shares and a short call option. That decomposition is the standard treatment in John C. Hull, Options, Futures, and Other Derivatives, and it is why the profit line rises with the share price until the strike and then runs flat. Everything in the tables above follows from adding those two payoffs, which means any error in a covered call figure can be traced to one of the two parts rather than to the combination.