Wheel Option Calculator for ThinkorSwim

It is a calculator for the wheel strategy, where you sell puts until you're assigned shares, then sell calls on those shares until they're called away. Ours is one ThinkorSwim custom quote that shows covered call returns on the call side of the option chain and put returns with breakeven prices on the put side.

It uses the built-in IsPut() function, which is true on a put row. I don't think thinkScript has an IsCall function, so the code checks !IsPut() for calls. An if/else runs the covered call math when !IsPut() is true and the cash-secured put math otherwise, and each label checks the same condition.

Each put shows 2 numbers. The left one is the premium for 1 contract as a percentage of the cost of 100 shares at the stock's last close. The right one is the breakeven price with a dollar sign: the strike minus the put's last price. In Part 2, BYD's 60 strike put in the 45-day series showed a $56.80 breakeven.

It switches the call side to measure returns from your costBasis input instead of the stock's last close, for shares you already own. It is set to no by default. The put side ignores it and always uses the stock's last close, so put numbers stay the same in either mode.

thinkScript requires a variable that gets its value inside an if/else to be declared above it with def and to get a value in both branches. That's why the call branch sets newBreakevenPrice to 0 and the put branch sets the covered call variables to 0. Without that, the script throws errors.

In the downloaded code, the cost basis version of the if-called return uses strikePriceGain, the gain from the current price. Change it to strikePriceGainExistingTradeMode in that line, and the right-hand number measures the gain from your entry. The premium return on the left is correct as downloaded.

For a call-only calculation, put it inside the if block, give the same variable a value such as 0 in the else block, and declare it with def above the whole if/else. For a put-only calculation, do the reverse. Then add a label with the matching IsPut() condition.

It saves a custom quote slot and keeps the chain clean. With the covered call and put calculators loaded separately, each prints on both sides of the chain, so half of the numbers aren't useful. The wheel calculator shows call math only on calls and put math only on puts, in one column.