Rates updated · Based on 93 tracked banks
Bank Gap Index — Methodology
The Bank Gap Index measures, in dollars, the annual savings interest a representative saver forgoes by holding cash at the U.S. national-average savings rate instead of a top-available rate. This page defines the metric, its inputs, its sources, and its update cadence. It is the canonical reference for the figure published on switchwize.com and in the public dataset.
- Published by
- SwitchWize Research Desk
- Current value
- $997 / year (June 2026)
- Update cadence
- Monthly
- Public dataset
- /data/bank-gap-index.json
What the Index measures
Most savers leave money in a savings account that pays far below the best widely-available rate. The shortfall is not caused by risk, lock-ups, or reduced insurance — a top-paying FDIC-insured account carries the same federal protection as a megabank account. It persists almost entirely because switching feels like friction. The Bank Gap Index puts a single dollar figure on that shortfall so it can be measured and tracked over time.
The Index answers one question: on a representative balance, how much annual interest does a saver give up by earning the national-average rate instead of a top-available rate?
The formula
Bank Gap Index = Representative Balance × (Top-Available APY − National-Average APY)
With the current inputs (June 2026):
= $25,000 × (4.37% − 0.38%)
= $25,000 × 3.99%
= $997 per year
Inputs and definitions
Representative Balance — $25,000
A fixed reference balance, held constant so that month-over-month changes in the Index reflect rate movements, not balance assumptions. $25,000 approximates a common mid-range savings or emergency-fund balance. The Index scales linearly with balance. The balance is a unit of measurement, not a claim about any individual's savings.
National-Average APY — 0.38%
The FDIC national average for savings deposits — the standard published benchmark for what U.S. savings accounts pay on average. It is intentionally an average, not a megabank floor; because the largest banks pay as little as 0.01%, the average itself sits well below what is readily available. Using the published national average keeps the Index conservative and anchored to an independent, recognized benchmark.
Top-Available APY — 4.37%
The mean of the top three savings APYs in SwitchWize's tracked set of savings institutions. A three-account average (rather than the single highest rate) is used deliberately: it represents a rate a saver can realistically obtain from more than one provider, rather than a single promotional outlier that may be capped, time-limited, or balance-restricted. The tracked set currently covers 93 institutions.
The Gap — 3.99 percentage points
The simple difference between Top-Available and National-Average APY (4.37% − 0.38%). Multiplied by the representative balance, it yields the dollar Index.
Sources
| National-Average APY | FDIC national rate for savings deposits |
| Top-Available APY | Mean of the top three rates in SwitchWize's tracked savings-institution set |
| Tracked set | 93 U.S. savings institutions monitored by SwitchWize, refreshed on a monthly cadence |
Update cadence and history
The Index is recalculated monthly and each month's value is recorded as a dated snapshot. The full history is published as a public dataset at /data/bank-gap-index.json, with one row per month containing the Index value, the national-average APY, the top-available APY, the gap in percentage points, and the number of institutions tracked. The history allows the metric to be read as a time series — rising when the spread between average and top rates widens, falling when it narrows.
Interpretation notes and limits
- It is a measure of forgone interest, not a loss in the accounting sense. A saver earning the national average has not lost money; they have earned less interest than was readily available. The Index quantifies that difference.
- It is not financial advice. The Index is a published economic measure. Whether moving funds is worthwhile for any individual depends on their balance, their time, and their circumstances.
- It is rate-driven, balance-fixed. Because the balance is held constant, changes in the Index over time reflect changes in the rate environment, not changes in any assumed balance.
- Top-Available is an average of three, by design. This makes the figure more conservative and more reproducible than a single best-rate headline.
Provenance
The Bank Gap Index is researched and published by the SwitchWize Research Desk, which monitors U.S. savings-institution rates and recomputes the Index monthly from live data. Figures on this page are current as of the date shown above and are superseded by each monthly update.
See the live Index
The current value, per-balance breakdown, and monthly history.
View the Bank Gap Index →