A rate moves from 2% to 3%. Saying it increased by one percent leaves an ambiguity. The difference is one percentage point, while the relative increase in the rate is 50%.
Keep the starting value visible
Subtracting 2 from 3 gives the one-point difference. For the relative change, divide that difference by the original rate: (3 − 2) / 2 = 0.5, or 50%. These are two descriptions of the same movement, using different reference points.
For a hypothetical balance of 1,000 and a single simple-interest period, 2% corresponds to 20 and 3% to 30. The increase in that interest amount is 10. This example excludes compounding, fees and tax.
Read what the percentage describes
A headline may discuss a rate, a payment, a price or a share of a total. Do not transfer the percentage change of one quantity to another without checking the calculation.
Write the before and after figures beside the claim. If either is missing, you may not have enough information to reproduce it.
Try the reverse direction
A fall from 3% to 2% is also one percentage point, but the relative decrease is one-third. The starting value matters. Add this check to your financial-example reading routine whenever a small-looking rate change carries a large-sounding percentage.