6 ms·

Just pay with a credit card, it's the optimal way by far (float, flexibility, rewards). No need to overthink it.

• matheusmoreira 23d ago
  It's worth to think about it a bit, especially in larger purchases. Significant discounts on the order of 5% to 10% can easily beat all credit card benefits, and not taking advantage of it leaves lots of money on the table. I have a little lookup table for this. Interest free installments mapped to cash discount necessary to beat the credit card. I just look it up. 1x -> ~1.9% 2x -> ~2.3% 3x -> ~2.8% 4x -> ~3.2% 6x -> ~4.0% 8x -> ~4.9% 10x -> ~5.7% 12x -> ~6.6% 18x -> ~9% 24x -> ~11-12% These numbers are actually conservative. There's a lot of credit card benefits that weren't priced in. I add a couple percent to the required discount numbers and round it up to compensate. 1x -> 4% 2x -> 5% 3x -> 5% 4x -> 6% 6x -> 7% 8x -> 7% 10x -> 8% 12x -> 9% 18x -> 12% 24x -> 14%
  • bluGill 23d ago
    Mathematically you are right. However those interest free payments are generally setup in such a way as to make it highly likely you won't pay it off by the end of the interest free period. The bills they send contain the minimum payment - designed to get you past that time. I don't trust my ability to get the fine print right - it only takes messing this up once to destroy all the gains from several times getting it right. So I use the credit card anyway and pay it off every month - that payoff is the one number I can get right every month.