Calculator Parameters

Gain %
Comm
Paste your complete Schwab CSV export - calculator will process all trades automatically
shares

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Calculator Parameters

%
Shares
Cost Basis
Last Close $
Last Purchase $
How it works

Set your target percentage and the calculator will determine how many shares you need to buy at the last close price to reach your goal. Prices are updated from latest market data.

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Investment Parameters

Current Assets $
Monthly Contribution $
Payment Start
Payment % %
%
How it works

Enter your starting assets, monthly contribution amount, and expected annual return rate. The calculator projects your investment growth over 10 years with annual compounding (contributions added monthly, returns applied at year-end).

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10-Year Projection

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Stock Trading Calculators - User Guide

Comprehensive documentation for all calculator tools

% Gain Shares Calculator (FIFO/LIFO)

Calculate the sell price needed to achieve a desired percentage return on your stock holdings using either FIFO (First In, First Out) or LIFO (Last In, First Out) accounting methods.

Parameters Explained
Trade Type: FIFO vs LIFO
  • FIFO (First In, First Out)
    • Sells the oldest shares first
    • Typically results in higher capital gains (if stock has appreciated)
    • More common for tax reporting
    • Example: If you bought shares in Jan 2023, Feb 2023, and Mar 2023, FIFO sells Jan shares first
  • LIFO (Last In, First Out)
    • Sells the newest shares first
    • Can result in lower capital gains (if recent purchases were at higher prices)
    • Useful for tax-loss harvesting strategies
    • Example: Same scenario, LIFO sells Mar shares first
Tip: Use FIFO for conservative gain estimates, LIFO to minimize short-term gains.
Number of Shares to Sell

Select how many shares from your holdings you want to sell. The slider adjusts based on your CSV data (up to your total holdings).

Example: If you own 250 shares total and want to sell 100, set the slider to 100.

Desired Gain %

Enter your target percentage gain. This is the profit percentage you want to achieve on your cost basis.

Example: If you want a 15% return, enter 15

Formula: Gain % = ((Sell Price - Cost Basis) / Cost Basis) × 100

Commission (Optional)

Enter any trading fees charged by your broker (default: $0.00). This will be deducted from your profit calculation.

Example: If your broker charges $6.95 per trade, enter 6.95

Save Results Toggle

When enabled, calculation results will be saved to your browser's local storage for future reference. You can view, sort, and delete saved results.

Note: Data is stored locally in your browser only. Clearing browser data will delete saved results.
CSV Format

Paste your trade history in the following comma-separated format:

Date,Ticker,Shares,Price
2024-01-15,AAPL,100,150.00
2024-02-20,AAPL,50,155.00
2024-03-10,AAPL,75,148.50
Field Descriptions:
  • Date: Purchase date (YYYY-MM-DD format)
  • Ticker: Stock symbol (e.g., AAPL, TSLA)
  • Shares: Number of shares purchased
  • Price: Purchase price per share
Important Notes:
  • Include the header row (first line)
  • One transaction per line
  • Dates must be in YYYY-MM-DD format
  • No dollar signs or commas in prices
Quick Tip: You can export this data from most brokerages (E*TRADE, Fidelity, Robinhood, etc.) in CSV format.
Step-by-Step Instructions
  1. Select Trade Type

    Toggle between FIFO and LIFO based on your accounting preference or tax strategy.

  2. Paste Trade History

    Copy your purchase transactions from your broker or spreadsheet and paste into the CSV textarea.

  3. Set Shares to Sell

    Use the slider or type a number to specify how many shares you want to sell.

  4. Enter Desired Return

    Type your target percentage gain (e.g., 15 for 15% profit).

  5. Add Commission (Optional)

    If your broker charges fees, enter the commission amount.

  6. Click Calculate

    The calculator will determine the exact sell price needed to achieve your target return.

  7. Review Results

    Results appear on the right side showing:

    • Required sell price per share
    • Total profit amount
    • Cost basis for shares being sold
    • Effective return percentage

  8. Save (Optional)

    Enable "Save Results" toggle before calculating to store the result for later reference.

Example Calculation
Scenario:

You own AAPL shares purchased on three dates:

  • Jan 15, 2024: 100 shares @ $150.00 = $15,000
  • Feb 20, 2024: 50 shares @ $155.00 = $7,750
  • Mar 10, 2024: 75 shares @ $148.50 = $11,137.50

Total: 225 shares, Total Cost: $33,887.50

Goal:

Sell 100 shares at 15% profit using FIFO, with $0 commission

FIFO Calculation:
  1. FIFO selects oldest 100 shares (all from Jan 15 purchase)
  2. Cost basis: 100 shares × $150.00 = $15,000
  3. Target profit: $15,000 × 15% = $2,250
  4. Required sell price: ($15,000 + $2,250) ÷ 100 = $172.50 per share
Result:

Sell Price Needed: $172.50 per share

Total Revenue: $17,250.00

Total Profit: $2,250.00 (15% return)

Saved Results Features
DELETE Button

Permanently removes the result from local storage. Use this to clean up old calculations you no longer need.

This action cannot be undone.

REMOVE Button

Temporarily hides the result from view without deleting it from storage. Refresh the page to see it again.

Useful for decluttering without losing data.

Result Cards Include:
  • Calculation timestamp
  • Ticker symbol with industry color coding
  • Trade method (FIFO/LIFO)
  • Number of shares
  • Required sell price
  • Expected profit
  • Return percentage
Tips for Best Results
  • Date Order: CSV data doesn't need to be sorted - the calculator will automatically sort by date
  • Multiple Tickers: Process one ticker at a time for clarity
  • Market Prices: Check current market price before setting return targets
  • Tax Considerations: FIFO often results in higher taxes; consult a tax advisor
  • Realistic Returns: Consider historical volatility when setting target percentages
  • Commission Impact: Small commissions can significantly affect low-volume trades
  • Export Data: Regularly export/backup your saved calculations

Cost Basis Reducer

Calculate how many shares you need to purchase at a target price to reduce your average cost basis by a desired percentage (1-20%).

Parameters Explained
Ticker Symbol

Enter the stock symbol you want to analyze (e.g., AAPL, TSLA, MSFT).

This helps organize your calculations and applies industry color coding to results.

Current Cost Basis

Your current average purchase price per share. This is calculated from your trade history.

Example: If you bought 100 shares at $150 and 50 shares at $160:

Cost Basis = (100×$150 + 50×$160) ÷ 150 = $153.33

Auto-Calculate: The calculator will compute this from your CSV data automatically.
Desired Reduction %

Target percentage reduction in your cost basis (slider: 1-20%).

Example: If your cost basis is $150 and you want a 10% reduction:

New Cost Basis = $150 × (1 - 10%) = $135.00

Reality Check: Large reductions (>15%) may require significant additional investment.
Target Purchase Price

The price per share at which you plan to buy additional shares.

This should be lower than your current cost basis to reduce your average.

Tip: Use current market price or set a limit order price.

CSV Format

Paste your existing holdings in the following format:

Date,Ticker,Shares,Price
2024-01-15,AAPL,100,150.00
2024-02-20,AAPL,50,160.00
2024-03-10,AAPL,25,155.00

The calculator will automatically:

  • Calculate total shares owned
  • Calculate current average cost basis
  • Determine shares needed at target price
Step-by-Step Instructions
  1. Enter Ticker Symbol

    Type the stock symbol (e.g., AAPL).

  2. Paste Trade History

    Copy your existing purchase transactions into the CSV textarea.

  3. Review Current Cost Basis

    The calculator will display your current average cost per share.

  4. Set Reduction Target

    Use the slider to select your desired reduction percentage (1-20%).

  5. Enter Target Price

    Specify the price at which you plan to purchase additional shares.

  6. Click Calculate

    The calculator will determine how many shares you need to buy.

  7. Review Results

    Results show:

    • Number of shares to purchase
    • Total investment required
    • New average cost basis
    • Total shares after purchase

Example Calculation
Current Holdings:
  • Jan 15: 100 shares @ $150.00 = $15,000
  • Feb 20: 50 shares @ $160.00 = $8,000
  • Mar 10: 25 shares @ $155.00 = $3,875

Total: 175 shares, Total Cost: $26,875

Current Cost Basis: $26,875 ÷ 175 = $153.57 per share

Goal:

Reduce cost basis by 10% by buying shares at $130.00

Calculation:
  1. Target new cost basis: $153.57 × (1 - 10%) = $138.21
  2. Current total cost: $26,875
  3. Let X = shares to buy at $130.00
  4. New average: ($26,875 + $130X) ÷ (175 + X) = $138.21
  5. Solve for X: X ≈ 328 shares
Result:

Shares to Buy: 328 shares @ $130.00

Investment Needed: $42,640

New Total Shares: 503 shares

New Cost Basis: $138.21 per share (10% reduction ✓)

Important: This is a significant investment ($42,640). Make sure you have the capital and that it aligns with your portfolio diversification strategy.
Use Cases & Strategies
Dollar Cost Averaging (DCA)

Systematically reduce your cost basis by buying during price dips.

Example: Stock drops 15%, you calculate how many shares to buy to lower your average.

Averaging Down

When a stock you believe in drops, buy more to position for recovery.

Example: After earnings miss, stock drops from $150 to $120. You buy more to reduce cost basis.

Position Sizing

Calculate exact shares needed to reach a target average price.

Example: You want your AAPL average at $140. Calculate how many shares at $130.

Budget Planning

Determine capital required for different reduction scenarios.

Example: Compare 5%, 10%, and 15% reduction to see investment needed.

Important Considerations
Risk Warnings
  • Throwing Good Money After Bad: Averaging down only works if the stock recovers. If the company fundamentals are weak, you're increasing your losses.
  • Opportunity Cost: Capital used to average down could be invested elsewhere with better prospects.
  • Concentration Risk: Buying more shares increases your exposure to a single stock, reducing diversification.
  • Margin Calls: If using leverage, averaging down can lead to margin calls if the stock continues to drop.
Best Practices
  • Fundamental Analysis: Only average down on stocks with strong fundamentals and temporary setbacks.
  • Set Limits: Decide maximum reduction % or investment amount before starting.
  • Diversification: Ensure this doesn't over-concentrate your portfolio.
  • Cash Reserves: Keep emergency funds separate - don't invest everything.
  • Time Horizon: Averaging down requires patience - ensure you can hold long-term.
Formula Breakdown

The calculation uses a weighted average formula:

New Cost Basis Formula:

New Avg = (Current Total Cost + (Shares to Buy × Target Price)) ÷ (Current Shares + Shares to Buy)

To solve for shares needed:

  1. Set: New Avg = Current Avg × (1 - Reduction %)
  2. Substitute into formula above
  3. Solve algebraically for "Shares to Buy"
  4. Result: Shares = (Current Shares × (Target Avg - Current Avg)) ÷ (Current Avg - Target Price)

General Tips & Information

Important information about using the Stock Trading Calculators, data privacy, and upcoming features.

Data Privacy & Storage
Your Data Stays Private

All calculator data is stored locally in your browser only. No data is transmitted to or stored on our servers.

  • ✅ Complete privacy - your financial data never leaves your device
  • ✅ Works offline after initial load
  • ✅ No server costs or maintenance
  • ✅ You maintain complete control over your data
localStorage (Persistent)

Purpose: Save calculation results long-term

Duration: Persists even after browser closes

Size Limit: ~5-10MB per domain

Used For:

  • Saved calculations (when toggle is ON)
  • User preferences
  • Calculation history
sessionStorage (Temporary)

Purpose: Auto-save form state during session

Duration: Cleared when browser tab closes

Size Limit: ~5-10MB per domain

Used For:

  • Current form inputs (auto-recovery)
  • Temporary calculations
  • CSV data being edited
Important Notes
  • Browser/Device Specific: Data doesn't sync across devices or browsers
  • Clearing Browser Data: Will permanently delete saved calculations
  • Private Browsing: May not persist localStorage after closing
  • Backup Recommended: Export important calculations regularly
Exporting & Importing Data
Export (Backup)

Download all your saved calculations as a JSON file for safekeeping.

When to Export:

  • Before clearing browser data
  • Before switching browsers/devices
  • Monthly backup routine
  • Before major browser updates

Feature coming in Phase 2

Import (Restore)

Upload a previously exported JSON file to restore your calculations.

When to Import:

  • After clearing browser data
  • When switching browsers/devices
  • Restoring from backup
  • Migrating to new computer

Feature coming in Phase 2

Best Practices

  • Always use YYYY-MM-DD date format for consistency
  • No dollar signs ($) or commas in prices
  • Include header row (Date,Ticker,Shares,Price)
  • One transaction per line
  • Keep CSV organized - sort by date if possible
  • Test with a small dataset first

  • Only save calculations you'll reference later
  • Delete old calculations to save storage space
  • Add notes/context to saved results (feature coming)
  • Export backups monthly or before major changes
  • Review and clean up saved data quarterly

  • Double-check CSV data before calculating
  • Verify results with manual calculation for large trades
  • Cross-reference with broker statements
  • Account for all commissions and fees
  • Use realistic return expectations based on market conditions
  • Consider tax implications (consult tax advisor)

  • Use on trusted devices only (not public computers)
  • Clear browser data after use on shared devices
  • Don't include personal info in saved calculations
  • Export backups to encrypted storage
  • Use secure passwords for your device/browser
  • Keep browser and operating system updated
Features Coming Soon
Industry Color Coding

Ticker buttons will display colors based on industry sector (Tech, Healthcare, Finance, etc.)

Phase 1
Sortable Results

Sort saved calculations by date, ticker, profit, Gain %, or shares

Phase 2
Filter & Search

Filter results by ticker, date range, or return percentage

Phase 2
Cloud Backup

Optional cloud backup to Google Drive or Dropbox (user-controlled)

Phase 3
Market Data Integration

Automatic ticker lookup and current price fetching

Phase 3
CSV Import/Export

Easily import trade data and export calculation results as CSV

Phase 2
Tax Lot Optimization

Advanced strategies for tax-loss harvesting and wash sale avoidance

Phase 3
Portfolio Management

Track calculations across different portfolios (IRA, 401k, Taxable, etc.)

Phase 3
Historical Analysis

Compare past calculations with actual results to improve accuracy

Phase 3
Troubleshooting
CSV Not Parsing Correctly

Possible Causes:

  • Missing header row
  • Incorrect date format
  • Extra spaces or commas
  • Currency symbols in prices

Solution:

Verify CSV format matches: Date,Ticker,Shares,Price with no extra characters.

Saved Results Disappeared

Possible Causes:

  • Browser data was cleared
  • Using private/incognito mode
  • Different browser or device
  • Storage quota exceeded

Prevention:

Export backups regularly and avoid clearing browser data.

Calculations Seem Wrong

Check:

  • CSV data accuracy (prices, shares, dates)
  • FIFO vs LIFO selection
  • Commission amounts
  • Number of shares selected

Solution:

Manually verify calculation with a simple example first.

Feature Not Working

Try:

  • Refresh the page (Ctrl+F5 / Cmd+Shift+R)
  • Clear browser cache
  • Update to latest browser version
  • Disable browser extensions temporarily

Still Not Working?

Check the browser console for errors (F12 → Console tab).

Disclaimer

Important Legal Notice:

These calculators are provided for informational and educational purposes only. They are not financial, investment, or trading advice.

  • Results are estimates based on input data accuracy
  • Past performance does not guarantee future results
  • Markets are volatile and unpredictable
  • Tax implications vary by individual circumstances
  • Consult a licensed financial advisor before making investment decisions
  • Consult a tax professional for tax-related questions

By using these calculators, you acknowledge that you are solely responsible for your investment decisions and their outcomes.