TAE – TIN Calculator (Spain)
Convert TIN to TAE and back: what rate you really pay or earn over a year when the nominal rate compounds monthly, quarterly or daily, with the Banco de España formula explained.

The TAE a bank publishes for a loan or deposit may also include fees and costs; this conversion is the purely financial part of the interest rate.
Formula: TAE = (1 + TIN/k)^k − 1, with k compounding periods per year.
Educational tool based on the financial equivalence of rates (Banco de España, Circular 5/2012). A product's regulated TAE may include fees: always compare the official TAE of the offer.
TIN and TAE: two numbers for the same product
The TIN (nominal interest rate) is the "label" annual rate: the one used to compute each instalment or interest credit. The TAE (effective annual rate) is what that rate really amounts to over a year when interest compounds several times: each settlement earns interest on the previous ones. That is why a 5% TIN compounded monthly equals a 5.116% TAE.
The formula, and why frequency matters
TAE = (1 + TIN/k)^k − 1, where k is the number of compounding periods per year: 12 for monthly, 4 quarterly, 365 daily. The larger k is, the further the TAE moves from the TIN: compound interest working within the year. With annual compounding (k = 1), TIN and TAE coincide.
The advertised TAE includes something more
For loans and consumer credit, the TAE a bank must publish also folds in fees and mandatory costs (Banco de España Circular 5/2012). This calculator does the pure financial part (rate and compounding), which has a name of its own: the Banco de España calls it the TEDR, the interest-rate component of the TAE without fees. The official TAE of an offer with fees will be higher than the TEDR you get here. To compare offers, always use each one's official TAE.
For deposits it works the same way, in your favour
On a deposit or interest-bearing account the logic is identical but you are the one collecting: a 3% TIN with monthly interest credits yields a 3.042% TAE if you reinvest them. The difference looks small; on large amounts and horizons it stops being small. The compound interest calculator shows by how much.
Worked example
Example: a mortgage advertises a 5% TIN with monthly instalments. TAE = (1 + 0.05/12)¹² − 1 = 5.1162%. In reverse: if a deposit promises a 5% TAE with monthly credits, the TIN behind it is 12 × (1.05^(1/12) − 1) = 4.8889%.
Frequently asked questions
What is the difference between TIN and TAE?
Why is the TAE higher than the TIN?
Can the TAE be lower than the TIN?
Is this TAE the same as the one in loan adverts?
Which compounding frequency should I pick?
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Sources
- Banco de España Circular 5/2012 of 27 June (TAE, annex 7) · Boletín Oficial del Estado
- Tipo Efectivo Definición Restringida (TEDR): the interest-rate component of the TAE · Banco de España, Portal del Cliente Bancario
Author: Thorben Rasmus Idel · Reviewed by: Nahar Geva · Last reviewed: