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AI-Powered Market Intelligence
Understand the reason behind any stock move.
Combine multiple entries and fees into one deterministic basis.
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Cost Basis Calculator
Calculate total cost basis after multiple buys and fees.
Use this deterministic cost basis calculator to aggregate purchase lots and fees into a single total and per-share basis.
Results
Total cost basis
$12,548.75
Total basis is $12,548.75 across 260.0000 shares ($48.26 avg).
- Total shares
- 260.0000
- Purchase cost
- $12,534.00
- Fees
- $14.75
- Average cost/share
- $48.26
Formula
Total Cost Basis = Sum of purchase costs + fees
Example
- Lot 1 shares: 120
- Lot 1 price: 45.2
- Lot 2 shares: 80
- Lot 2 price: 49.8
- Lot 3 shares: 60
- Lot 3 price: 52.1
- Total fees: 14.75
What does this mean?
- •Accurate cost basis is critical for P/L and tax workflows.
- •Include fees for realistic basis estimates.
- •Use the same lot methodology as your broker for reconciliation.
Keep cost basis clean and auditable
Combine multiple entries and fees into one deterministic basis.
What is a cost basis?
Use this deterministic cost basis calculator to aggregate purchase lots and fees into a single total and per-share basis. In practice, this means you can quantify cost basis using lot 1 shares, lot 1 price, lot 2 shares, lot 2 price, lot 3 shares, lot 3 price, and total fees without relying on hidden assumptions or black-box scoring.
Primary input set for this calculator: Lot 1 shares, Lot 1 price, Lot 2 shares, Lot 2 price, Lot 3 shares, Lot 3 price, Total fees.
How to calculate cost basis
- 1.Step 1: Enter lot 1 shares with the timeframe/context you want to evaluate.
- 2.Step 2: Enter lot 1 price with the timeframe/context you want to evaluate.
- 3.Step 3: Enter lot 2 shares with the timeframe/context you want to evaluate.
- 4.Step 4: Enter lot 2 price with the timeframe/context you want to evaluate.
- 5.Step 5: Enter lot 3 shares with the timeframe/context you want to evaluate.
- 6.Step 6: Enter lot 3 price with the timeframe/context you want to evaluate.
- 7.Step 7: Enter total fees with the timeframe/context you want to evaluate.
- 8.Step 8: Apply formula Total Cost Basis = Sum of purchase costs + fees.
- 9.Step 9: Interpret output together with risk, liquidity, and catalyst context.
Why this metric matters
This metric turns trade assumptions into explicit numbers for sizing, entry/exit planning, and portfolio discipline.
Pair this calculator with catalyst context from headlines, filings, and options flow to avoid relying on isolated numbers.
When to use this calculator
- ✓Before opening a new position where cost basis impacts sizing or risk.
- ✓After a catalyst to quantify how much conditions changed versus your baseline.
- ✓When comparing setups across multiple tickers with one consistent formula.
- ✓During weekly review to keep decision-making tied to measurable inputs.
Common scenarios
Accurate cost basis is critical for P/L and tax workflows
Use this cost basis workflow to quantify this scenario with deterministic inputs.
Include fees for realistic basis estimates
Use this cost basis workflow to quantify this scenario with deterministic inputs.
Use the same lot methodology as your broker for reconciliation
Use this cost basis workflow to quantify this scenario with deterministic inputs.
Event reaction review
Recalculate cost basis immediately after earnings, filings, or macro headlines.
Interpretation tips
- •Re-run cost basis whenever key inputs change materially, not only when price moves.
- •Document assumptions so the same methodology can be repeated across watchlist names.
- •Use this metric as one layer in the decision stack, not as a standalone trade trigger.
Data caveats
- –Outputs are deterministic from your inputs; input quality determines output quality.
- –This page does not auto-adjust for broker fees, taxes, or slippage unless you include them in your assumptions.
- –Validate corporate action details, filing dates, and data freshness before acting on results.
FAQ
How does the cost basis calculator work?
Cost Basis Calculator is deterministic and uses only your inputs (lot 1 shares, lot 1 price, lot 2 shares, lot 2 price, lot 3 shares, lot 3 price, total fees). Formula: Total Cost Basis = Sum of purchase costs + fees.
What does this output tell me in practice?
Calculate total cost basis after multiple buys and fees. Pair this with a stop-loss and thesis review, not just return math.
Does the cost basis calculator use real-time market feeds?
No. This page does not auto-pull live data. You control all inputs and can rerun instantly as market conditions change.
Can I use this result directly for trading decisions?
Use it as a planning layer. Combine with position sizing, liquidity, and catalyst context before any execution.
Related tools
Average Buy Price Calculator→Realized Gain/Loss Calculator→Unrealized Gain/Loss Calculator→Partial Sell Calculator→
Popular searches
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