Weighted Expense Ratio (ER) Calculator - Tool
What the calculator is for
The calculator helps answer a simple question: "What is this portfolio actually paying in fund operating expenses each year?" Expense ratios are ongoing fund costs that reduce a fund’s return before it hits an account.
Key Takeaways
- The tool converts a list of holdings into an asset-weighted expense ratio and an estimated annual ER cost in dollars.
- Weights are based on dollar amounts, not target percentages - useful for live portfolios with drift.
- The table breaks out costs by holding to help users better understand how each position contributes to overall expenses.
Inputs - what each field means (and why it matters)
- Position (name)
A label for each holding (ETF, mutual fund, or cash proxy). Names don’t affect math - they help interpret the output table. - Amount $
Dollar value currently invested in that holding. The calculator uses these amounts to compute each holding’s weight in the portfolio. - ER %
The fund’s stated expense ratio (annual, in %). Enter each holding’s current ER from its prospectus or fund page. Lower isn’t always “better,” but costs are persistent - so getting the number right matters. - + Add position / Remove (×)
Add as many lines as needed; delete lines to keep the list aligned with the actual portfolio.
A quick best practice: enter actual dollar amounts copied from account statements. Percent targets can drift; the calculator reflects what is really owned today.
How the math works (plain English)
- Total portfolio
Sum of all Amounts. - Weight (per holding)
Weight = Holding Amount ÷ Total portfolio. - Blended ER
Blended ER = Σ(Weight × Holding ER) → an asset-weighted expense ratio for the entire portfolio. - Annual ER cost ($/yr)
Annual Cost = Total portfolio × Blended ER.
The tool estimates the dollar amount associated with each holding based on its weight and expense ratio. This makes a 0.12% fund on a large allocation look larger in dollars than a 0.20% niche sleeve with a tiny weight - useful for prioritizing changes.
Reading the outputs
- Total portfolio - the combined market value analyzed.
- Blended ER - the single expense ratio the entire portfolio effectively pays.
- Annual ER cost - the real-world dollar drag per year at current balances.
- Positions table (Weight | ER | $/yr) - a breakdown showing each holding’s weight, ER, and estimated annual cost contribution.
This interactive tool is for educational purposes only. It provides a simplified illustration of how fund fees, such as front-end loads and expense ratios, can affect hypothetical ending portfolio values over a selected time horizon. The calculations use user-entered inputs and annualized assumptions that may not reflect actual market conditions, trading behavior, fee schedules, or individual circumstances. Outputs are hypothetical and are not predictions, projections, guarantees, or estimates of future performance. Real outcomes may differ materially. Nothing presented here should be interpreted as investment advice, financial advice, or a recommendation to buy, sell, or select any specific fund or fee structure.
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