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Net Interest Margin Calculator

Work out net interest margin instantly with clear inputs, formula shown and shareable results.

About Net Interest Margin Calculator

Net interest margin is net interest income over average earning assets — the core profitability measure for a bank. Splitting it into asset yield and funding cost shows whether pressure is coming from lending competition or deposit repricing.

Formula

Net interest margin

NIM = (interest income - interest expense) / average earning assets

Worked example

With the default values below, Net Interest Margin Calculator returns Net Interest Margin of 3.6471%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Interest Incomeminimum 0
72,000,000
Interest Expenseminimum 0
41,000,000
Average Earning Assetsminimum 0
850,000,000

Results

Net Interest Margin
3.6471%
Net Interest Income
$31,000,000.00
Yield On Earning Assets
8.4706%
Cost Of Funds On Earning Assets
4.8235%

Step by step

  1. 1Values used
  2. 2Net interest margin
  3. 3Net Interest Margin= 3.6471
  4. 4Net Interest Income= 31,000,000.00
  5. 5Yield On Earning Assets= 8.4706
  6. 6Cost Of Funds On Earning Assets= 4.8235

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Figures are estimates based on the inputs given. Bank charges, regulatory minima and market rates change and differ between institutions and jurisdictions. This is not financial advice — confirm with your bank or treasury policy.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Figures are estimates based on the inputs given. Bank charges, regulatory minima and market rates change and differ between institutions and jurisdictions. This is not financial advice — confirm with your bank or treasury policy.

Frequently Asked Questions

Why use earning assets rather than total assets?

Because cash and fixed assets generate no interest, so including them understates the margin the lending book actually achieves.

What drives margin expansion?

A rising rate environment usually helps, since assets reprice faster than sticky deposits.

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