ESPP Calculator
An ESPP lets you buy company stock at a discount. With a lookback, your effective discount and return can be much larger than the stated rate.
Want to understand the concept, not just the number? Read The ESPP Guide and more below.
How it's calculated
An ESPP lets you buy your employer stock at a discount, often 15 percent, using money set aside from your paychecks over an offering period. The best plans add a lookback, which sets your price off the lower of the price at the start of the period and the price on the purchase date. If the stock climbed during the period, that lookback makes your real discount much bigger than the headline number.
Here is how the default works. You contribute $2,000 over a six month period. The stock started at $20 and finished at $25, and the plan has a 15 percent discount with a lookback. Your price is 15 percent off the lower $20 start price, so $17.00 a share. Your $2,000 buys about 117.65 shares, which are worth $2,941.18 at the $25 purchase price. Sell right away and that is a $941.18 gain, a 47.06 percent return on your money before tax.
Notice the effective discount is 32 percent, not 15 percent, because the lookback locked in the lower price while the stock rose. Without a lookback your price would be 15 percent off the $25 end price, or $21.25, and the return would be 17.65 percent. Either way the gain is close to guaranteed if you sell at purchase, which is why many people treat a good ESPP as one of the highest-return, lowest-risk benefits they have.
Assumptions
- Assumes you sell all shares at the purchase-date price, so the gain shown is before any tax.
- The IRS $25,000 per year purchase limit and your own plan contribution cap are not enforced here, so enter an amount your plan allows.
Last updated: 2026-08-08
These assumptions follow our general methodology.
Frequently asked questions
Is an ESPP worth it?
For most people with a discount and a lookback, yes. Selling right at purchase captures a return that is hard to beat elsewhere, often well above the stated discount. The main risks are holding the shares too long and ending up too concentrated in one company stock.
How does the ESPP lookback work?
The lookback sets your purchase price off the lower of the share price at the start of the offering period and the price on the purchase date, then applies the discount. If the stock rose during the period, you buy at the older, lower price, so your effective discount is larger than the stated one.
How much can I put into an ESPP?
The IRS caps the value you can buy at $25,000 per calendar year, measured at the start-of-period price, and plans set their own contribution percent limits on top of that. Check your plan documents for the exact figures.
How is ESPP stock taxed?
The discount is taxed as ordinary income, and any further gain is a capital gain. If you sell right away it is a disqualifying disposition and most of the gain is ordinary income. Holding long enough for a qualifying disposition can shift more of it to lower capital-gains rates. The RSU calculator covers a related kind of stock compensation.
Should I sell my ESPP shares right away?
Selling at purchase locks in the discount and avoids putting too much of your net worth in one stock. Holding can lower your tax if you meet the qualifying-disposition rules, but it adds market risk. Many people sell most shares quickly and treat the discount as the reward.