The investment percentage gain or loss compares what a position is worth now, or what you sold it for, with what you put into it, and expresses the difference as a share of the original amount. A positive result is a gain and a negative result is a loss. The arithmetic needs only a starting and an ending value. Deciding which costs and income belong in them changes the answer more.
What the Calculator Measures
The tool takes a starting value and an ending value and returns two outputs:
- Change is the percentage gain or loss relative to the starting value.
- Difference is the raw amount gained or lost, in the same units you entered (dollars, price per share, index points).
Change is (end − start) / start × 100. The division turns a dollar result into a comparable one: a $150 profit on $500 is a 30% gain, while the same $150 on $1,000 is 15%. Percentages let you rank positions of different sizes against each other and against a benchmark.
Because the starting value is the denominator, it cannot be zero. An investment with no cost has no defined percentage return.
What to Enter as the Starting and Ending Value
Per-Share Price or Total Position
You can enter either the price per share or the total value of the position. If you bought all your shares in one trade and sold them all in one trade with no costs, both approaches give the same percentage. Buying 100 shares at $30 and selling at $38 is a 26.67% gain whether you enter 30 and 38 or 3,000 and 3,800. Only the Difference changes: $8 per share versus $800 for the position.
Use total values when you bought in several lots at different prices, paid fees, or received income, because the per-share figures no longer describe your actual result. For a position built in several lots, the total cost of all lots is the starting value and the total proceeds or current value is the ending value. To see how each lot performed, run the calculation separately with each lot’s own cost.
Realized vs. Unrealized Results
For a position you have closed, the ending value is the sale proceeds. For a position you still hold, enter the current market value instead. The result is an unrealized gain or loss: it describes where the position stands today, not money you have locked in.
Folding In Fees and Dividends
The formula itself has no fee or dividend field, so you build them into the two inputs:
- Starting value: purchase cost plus any commission or fee paid to buy.
- Ending value: sale proceeds (or current value) minus any commission or fee paid to sell, plus dividends or other cash distributions received while you held the position.
Quoted percentage changes for a stock or fund usually reflect price only. Entering your own adjusted figures turns the calculator into a measure of what you actually made.
Worked Examples
Price only. You buy 50 shares at $40 for $2,000 and later sell at $52 for $2,600. Enter 2,000 and 2,600. The Difference is $600 and the Change is 30%.
With trading costs. Suppose you paid $10 to buy and $10 to sell. The starting value becomes $2,010 and the ending value becomes $2,590. The gain is $580, and $580 / $2,010 × 100 = 28.86%. Twenty dollars of fees cost more than a percentage point of return on a position this size.
With dividends. Now add $1.50 per share in dividends received during the holding period, or $75 on 50 shares. The ending value is $2,590 + $75 = $2,665. The gain is $655, and $655 / $2,010 × 100 = 32.59%. Dividends paid after you sold do not belong in the ending value.
An index. The same formula measures an index over a period. If an index moves from 4,800 to 5,040, the change is (5,040 − 4,800) / 4,800 × 100 = 5%. A price index measures price movement only. Holders of funds tracking it also receive dividends, so their total return can be higher than the index’s headline move.
Gains and Losses Are Not Symmetric
A loss and the gain needed to recover from it are not the same size, because the recovery is measured from a smaller base. If a $1,000 position falls 20% to $800, the move back to $1,000 is $200 on $800, a 25% gain.
The general formula is: required gain = loss / (1 − loss), with the loss written as a decimal.
| Loss from cost | Gain needed to break even |
|---|---|
| 10% | 11.11% |
| 15% | 17.65% |
| 20% | 25.00% |
| 25% | 33.33% |
| 30% | 42.86% |
| 50% | 100.00% |
To check a specific position, enter today’s value as the starting value and your original cost as the ending value. The Change output is the gain the position needs to get back to cost. That figure still excludes any fees you will pay to sell.
The same asymmetry applies in reverse. A 50% gain followed by a 50% loss does not return you to even: $100 becomes $150, then $75. The overall result is −25%. Always measure the total change from the original start rather than adding or averaging the percentages of each step.
Working Backward From a Percentage
Rearranging the formula answers related questions:
- Ending value from a percentage: End = Start × (1 + p / 100). A 10% gain on $20,000 is $2,000, leaving $22,000. A $100 position that rises 800% is worth $100 × 9 = $900, not $800.
- Percentage from a profit: p = Profit / Start × 100. Investing $500 and receiving $1,000 back is a $500 profit and a 100% gain, which doubles your money, before costs.
- Original investment from a profit and a percentage: Start = Profit / (p / 100). A $500 profit that represents a 25% gain implies an original investment of $2,000.
Special Cases
Options
For a purchased option, the starting value is the premium you paid times the contract multiplier times the number of contracts, plus commissions. On standard U.S. equity options, the multiplier is 100 shares per contract. Buying one call at $2.00 costs $200; selling it at $3.50 returns $350. The gain is $150, or 75%. The most a bought option can lose is the premium, a 100% loss. For options you sell (write), the premium received is not a meaningful base, because the potential loss can far exceed it. Measuring the result against the margin or capital set aside is more informative there.
Short Positions
A short seller profits when the price falls, so the calculator’s sign runs the wrong way. A short entered at $50 and covered at $40 shows −20% if you enter 50 and 40, yet the trade made 20% relative to the entry price. Enter the values in reverse order only if you check the result: reversing them divides by the exit price instead of the entry price, which gives 25% for this trade. The correct figure is (entry − exit) / entry × 100. Losses on a short are not capped at 100%, because the price can keep rising.
Portfolios With Deposits or Withdrawals
The two-number formula assumes no money moved in or out. If you started a brokerage account with $10,000, added $5,000 during the year and ended at $16,500, the simple calculation reports 65%. Most of that is your own deposit. Subtracting net contributions from the ending value gives a rough idea: $11,500 against $10,000 is 15%. That shortcut still ignores when the deposit was made. Precise portfolio returns use time-weighted or money-weighted methods, which account for the timing of each cash flow. Some broker statements report one of these.
What the Calculation Leaves Out
Time. A 25% gain over three months and a 25% gain over ten years are the same output here. To compare holdings with different holding periods, convert to an annual rate: annualized return = (End / Start)^(1 / years) − 1. A 25% gain over three years works out to about 7.72% a year, not 8.33%, because each year’s growth compounds on the last.
Inflation. The result is a nominal return. If prices rose over your holding period, the purchasing power you gained is smaller than the percentage shows.
Taxes. Capital gains and dividend taxes reduce what you keep, and the rate depends on your jurisdiction, account type and holding period. Treat the result as a pre-tax figure unless you subtract tax from the ending value yourself.
Other costs. Account fees, fund expense ratios, slippage between the expected and executed price, financing charges on leveraged positions and currency conversion on foreign holdings all reduce returns. Include any you can quantify in the starting or ending value.
Risk. Two investments with the same percentage gain may have taken very different paths to get there. The result says nothing about how far a position fell along the way.
Reading the Result in Context
A percentage change becomes more useful when you compare it with something: an index over the same dates, or peers in the same sector, to judge relative strength.
Keep percentages and percentage points separate. If a fund’s annual return goes from 4% to 6%, it rose by 2 percentage points, which is a 50% increase in the return itself. Mixing the two can make a modest change sound dramatic, or the reverse.
FAQ
Is percentage gain the same as return on investment?
For a single position with no cash flows in between, yes. Both divide the net gain by the amount invested. The terms diverge when people include different costs or income, so check what a quoted figure contains before comparing it with your own.