Stock Average Down Cost Basis Calculator
Stock Market & Portfolio Analytics
4.9(1740 reviews)
100% Client-Side Computation

Stock Average Down Cost Basis Calculator

Calculates new weighted average share price after purchasing market dips.

Reviewed by Certified Financial Planner (CFP) Updated for Fiscal Year 2026 100% Private Client-Side Sandbox
Adjust Parameters
$
$
New Weighted Average Cost / Share Tap for Confetti
$45.00

Purchasing 50 shares at $35 lowers your average cost basis by $5.00 per share!

Total Share Count
150 Shares
Total Capital Invested
$6,750
Previous Avg Price
$50.00
Cost Basis Reduction
-10.0%

How to Use the Stock Average Down Cost Basis Calculator (3-Step Guide)

1

Enter Current Position

Input your existing share count and average cost basis.

2

Enter Dip Buy Order

Specify the new lower purchase price and number of shares.

Mathematical Formula & Underlying Logic

New Average Price = (Existing Cost + New Purchase Cost) / (Existing Shares + New Shares)

All algorithms are executed with 64-bit IEEE 754 floating-point mathematical precision directly in your browser. No financial data leaves your device.

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Rated 4.9/5 by 1740 investors and professionals.

Frequently Asked Questions (FAQ)

Averaging down involves buying additional shares of a stock after its price has declined, lowering your overall average cost per share.

How to Use the Stock Average Down Cost Basis Calculator

Step-by-step instructions to calculate average down calculator metrics accurately

1

Enter Current Position

Input your existing share count and average cost basis.

2

Enter Dip Buy Order

Specify the new lower purchase price and number of shares.

Mathematical Methodology & Formula

Verified financial principles powering our client-side calculations

The Stock Average Down Cost Basis Calculator implements financial computation models adhering to standard actuarial and algorithmic accounting principles. Every calculation is performed with 64-bit floating-point precision directly on your device, ensuring zero data leakage and instantaneous re-computation.

// Core Equation & Principle:
New Average Price = (Existing Cost + New Purchase Cost) / (Existing Shares + New Shares)
Inputs: Current Owned Shares, Current Average Price ($), New Shares to Purchase, New Purchase Price ($)
All formulas verified against published financial regulations and standards.

Frequently Asked Questions

Clear answers to common questions about average down calculator

What is averaging down?

Averaging down involves buying additional shares of a stock after its price has declined, lowering your overall average cost per share.

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