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Use the Fee Calculator in the Midaz Module to estimate fees before you process a real Transaction. The Fee Calculator is read-only. It does not create a Transaction or change any Ledger balance.

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Before you start

  • Enable the Fees Engine in Midaz module settings.
  • You need at least one Fee Package saved.
  • You need the source and destination Account aliases you want to test against.

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Running an estimation

1
In the Midaz Module sidebar, expand Fees Engine and click Calculator.
2
Fill in the estimated transaction. See the Field guide below for each input.
3
Click Calculate Fees to run the estimation.
4
Review the results displayed below the form.

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Field guide

The Fee Calculator is a read-only tool. It does not affect the ledger or create any transactions. You can run as many estimations as needed safely.

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Understanding the results

After you run an estimation, the Fee Calculator shows a detailed breakdown of the calculation:

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Summary

  • Total Fee - The sum of all fees for the transaction
  • Net Amount - The amount the destination would receive after deductible fees

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Fee breakdown

For each fee rule applied, you’ll see:

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Estimation examples

Scenario: Test a $2.00 flat fee on a $100 transferInput:
  • Fee Package: Standard Transfer Fee
  • Asset: USD
  • Amount: 100.00
  • Source: @customer/checking
  • Destination: @merchant/revenue
Expected Result:
  • Total Fee: $2.00
  • Net Amount: $98.00 (if deductible) or $100.00 (if not deductible)
Scenario: Test a 1.5% fee on a $500 transferInput:
  • Fee Package: Percentage Transaction Fee
  • Asset: USD
  • Amount: 500.00
  • Source: @customer/savings
  • Destination: @vendor/payments
Expected Result:
  • Total Fee: $7.50 (1.5% of $500)
  • Calculation: 500 × 0.015 = 7.50
Scenario: Test max(flat, percentage) fee on different amountsTest 1 - Small transaction ($30):
  • Flat: $1.00
  • Percentage: 2% = $0.60
  • Result: $1.00 (flat is higher)
Test 2 - Large transaction ($200):
  • Flat: $1.00
  • Percentage: 2% = $4.00
  • Result: $4.00 (percentage is higher)
Scenario: Package with two fees applied in priority orderFee A (Priority 1): 1% on original amount Fee B (Priority 2): 0.5% on after fees amountInput: $1000 transactionExpected Result:
  • Fee A: $10.00 (1% of $1000)
  • Fee B: $4.95 (0.5% of $990)
  • Total Fee: $14.95

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Use cases for fee estimation

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Validate new fee packages

Before you enable a new fee package, run estimations at various transaction amounts. Make sure the fees are correct across the full amount range.

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Test edge cases

Estimate transactions at minimum and maximum amount boundaries to verify fee behavior at the limits of your configured ranges.

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Compare fee structures

Run the same transaction through different fee packages to compare outcomes and choose the best structure for your use case.

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Document expected fees

Use estimation results to create documentation for your finance team or customers about expected fee amounts.

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Debug fee issues

If a transaction shows unexpected fees, use the Fee Calculator to reproduce the scenario and understand the calculation breakdown.

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Best practices

  • Test full amount ranges - Do not test only one amount. Estimate transactions at the minimum, the maximum, and several points in between.
  • Verify priority ordering - When packages have multiple fees, confirm they apply in the expected order.
  • Check waived accounts - Test with accounts that the fee package waives. Confirm the results exclude them from fees.
  • Document your tests - Keep a record of estimation results for audit and compliance purposes.
  • Share with stakeholders - Use estimation breakdowns to align with finance teams on expected fee outcomes before going live.

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What to do next

After validating the fee result, adjust the Fee Package if needed in Editing a Fee Package, or create a real Transaction in Creating a Transaction.

API equivalent

Estimate Fees endpoint