Shares Calculator
How many shares does your money buy? What will a block of shares cost once the broker takes its cut? What price per share can you afford for a fixed budget? This calculator answers all three: shares from an investment amount, total cost from a share count, or price per share from a budget, with a transaction summary that shows the subtotal, the commission, your average cost per share, and the break-even price.
Quick Answer
$10,000 at $150 per share with a $10 commission buys 66.6000 shares: the fee comes out first ($9,990 left to invest), so the average cost per share is $150.15 and the break-even price is $150.15. The tool is pre-filled with this exact case in shares mode.
Key takeaways
- Three questions, one tool: shares from a budget, total cost from a share count, or price per share from a budget. The input labels change with the mode.
- The commission is a flat fee, and where it lands matters: it is subtracted from your budget in shares and price modes, and added to the bill in cost mode.
- Average cost per share always includes the commission, which is why it sits above the quoted share price whenever a fee is charged.
- The tool reports fractional shares (66.6000). Many brokers still sell whole shares only, so round down if yours does.
How to use the shares calculator
Pick the calculation type, check the pre-filled example, swap in your own numbers, and click Calculate. The result headline answers your question, and the transaction summary underneath breaks the trade into its parts.
- Choose the mode: Number of Shares (budget → share count), Total Cost (share count → full bill), or Price Per Share (budget → affordable price). Switching modes relabels the two inputs and hides the previous result.
- Shares mode: enter your investment amount and the price per share. The tool subtracts the commission first, then divides what is left by the price.
- Cost mode: enter the number of shares and the price per share. The tool adds the commission to shares × price, which is the number your broker actually charges.
- Price mode: enter your investment amount and the number of shares. The tool subtracts the commission, then divides by the shares to find the highest price per share your budget supports.
- Commission: optional flat fee. Blank means zero. It changes the maths (see the next section), so enter it honestly rather than leaving a real fee out.
- Copy or share the results box: the copied line carries the mode, the headline answer, and every summary row, so the numbers travel with their meaning.
The three formulas, each worked through the tool
Every mode is one division or multiplication with the commission placed deliberately. Each example below is a real run of the calculator with the stated inputs.
Total cost = (shares × price per share) + commission
Price per share = (investment − commission) ÷ shares
Average cost per share = (subtotal + commission) ÷ shares | Break-even = average cost per share
| Mode and inputs | Headline answer | Avg cost / break-even | Reading the result |
|---|---|---|---|
| Shares: $10,000, $150/share, $10 fee (worked example) | 66.6000 | $150.15 | $9,990 buys the shares; the fee lifts your cost above $150 |
| Cost: 100 shares, $150/share, $10 fee | $15010.00 | $150.10 | The bill is shares × price plus the fee |
| Price: $10,000, 100 shares, $10 fee | $99.90 | $100.00 | $99.90 is the most you can pay per share; average cost stays $100 |
| Shares: $10,000, $150/share, no fee | 66.6667 | $150.00 | With no fee the average cost equals the share price exactly |
The flow inside shares mode, the default, runs like this:
$10,000 in
$10,000 − $10 = $9,990
$9,990 ÷ $150 = 66.6
avg cost $150.15
A related but different question is how many shares a company has issued in total. That is shares outstanding, a company-level figure the outstanding shares calculator derives from market capitalization; this tool answers the personal version, how many of those shares your money buys. Corporate actions can also change your share count overnight: a stock split multiplies it, while a consolidation of shares (reverse split) shrinks it, and both leave the total value of your holding unchanged.
The commission question, answered honestly
A flat commission changes the answer in a way percentage-fee calculators gloss over, because a flat fee lands differently depending on the mode. In shares and price modes the fee is subtracted from your budget before anything is bought: it is money that never becomes stock. In cost mode it is added to the bill: it is money on top of the stock.
Three honest disclosures about how this tool treats the fee. First, the fee input is optional and blank means zero; the tool never invents a fee. Second, the Fees row shows +$10.00 when a positive fee is entered and $0.00 otherwise, even if a negative fee was typed, because a negative fee is silently accepted and increases the shares you can buy; type a fee as a positive number and double-check the sign. Third, average cost per share always spreads the fee across your shares, so with a $10 fee on 66.6 shares your true cost is $150.15 per share, not the $150 quote, and the break-even price is the same $150.15: sell below it and the trade loses money after the fee. The old version of this page ignored none of this in its code but explained none of it in its text; the code is unchanged, the explanation is new. Once you own the shares, the next question is how they performed: the shareholder return calculator takes the share count and prices from here and computes your total return including dividends, and the dividends calculator totals the income stream a dividend-paying holding produces.
What competing calculators miss
The top results for this keyword each answer one of the three questions and ignore the rest:
- Symbolab “How Many Shares Can I Buy”: the formula is right (subtract the fee, then divide) and it warns about fractional shares, but it answers only the shares question, with no total-cost mode, no price-per-share mode, and no average-cost or break-even readout.
- Sage Investment Stock Calculator: adds a break-even price, but its commission is a percentage of the trade, not a flat fee, and it has only the one mode.
- Sage Stock Purchase Calculator: clean total-cost tool, (price × shares) + commission, but that is the entire tool: no shares mode, no price mode, no fee-aware summary.
- Calculator Doc Shares Calculator: a different animal entirely: buy price, sell price, profit and loss. No commission input at all, so its profit figures ignore the one cost every real trade pays.
- FinanceWave Share Quantity Calculator: fast shares-only tool with copy and reset, but one mode and no fee handling.
- InvestmentIQ “How Many Shares Should I Buy”: thoughtful guidance on diversification and fractional shares, but an article, not a working calculator.
- TradingView Stock Size Calculator: position sizing by account risk for active traders, a different intent from an investor asking what a budget buys.
- The gap this page fills: all three modes on one page with the fee placed correctly in each, a full transaction summary (subtotal, fees, total, average cost, break-even) under every answer, and the fee quirks stated openly instead of buried.
Frequently asked questions
Divide what is left after the commission by the share price. With $10,000, a $150 share price, and a $10 commission: ($10,000 − $10) ÷ $150 = 66.6000 shares. Without the commission it would be 66.6667 shares.
Shares = (investment amount − commission) ÷ price per share. The commission comes out first because it is money that never becomes stock. Leave the commission blank and the formula simplifies to investment ÷ price.
It is a flat fee, and its position depends on the mode. In shares and price-per-share modes it is subtracted from your budget before shares are bought; in total-cost mode it is added to the bill. The average cost per share always includes it.
The share price at which the trade neither gains nor loses after the commission: exactly the average cost per share. In the worked example it is $150.15. Sell above it and the trade profits; sell below it and it loses, fee included.
The subtotal plus the commission, divided by the number of shares. It is your true per-share cost, and it sits above the quoted price whenever a fee was charged: $150.15 against a $150 quote in the worked example.
The tool reports fractional shares (66.6000) because the maths is exact. Whether you can actually buy them depends on your broker: many still sell whole shares only, in which case round down to 66. Commission-free brokers with fractional-share programs will fill the exact fraction.
Switch to Total Cost mode and enter the share count, the price per share, and the commission. The formula is (shares × price per share) + commission. For 100 shares at $150 with a $10 fee, the total is $15010.00.
Switch to Price Per Share mode and enter your investment amount and the number of shares. The tool subtracts the commission first, then divides: ($10,000 − $10) ÷ 100 = $99.90, the highest per-share price your budget supports.
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References
- U.S. Securities and Exchange Commission. A Guide to Saving and Investing. Accessed October 23, 2026.
- U.S. Securities and Exchange Commission, Investor.gov. Stocks. Accessed October 23, 2026.
- U.S. Securities and Exchange Commission, Investor.gov. How the Stock Market Works. Accessed October 23, 2026.
- U.S. Securities and Exchange Commission. Stock Splits. Accessed October 23, 2026.
- U.S. Securities and Exchange Commission, EDGAR. Company Filings Search (EDGAR). Accessed October 23, 2026.
- U.S. Internal Revenue Service. Topic No. 409, Capital Gains and Losses. Accessed October 23, 2026.
- U.S. Internal Revenue Service. Topic No. 404, Dividends. Accessed October 23, 2026.
- U.S. Internal Revenue Service. Publication 550, Investment Income and Expenses. Accessed October 23, 2026.
- Federal Reserve Bank of St. Louis, FRED. S&P 500 Index (SP500). Accessed October 23, 2026.
- CFA Institute. Global Investment Performance Standards (GIPS). Accessed October 23, 2026.