15-year mortgages already have lower rates than 30-year mortgages, so the impact of points is smaller in absolute terms. A 0.25% reduction on a 15-year at 5.75% saves less than the same reduction on a 30-year at 7%. But the shorter term also means you reach break-even faster.
15-Year Points
On a $300K 15-year at 5.75%: one point ($3,000) reduces to 5.5%, saving about $43/month. Break-even: 70 months. The savings per point are smaller because the base rate is lower and the loan amortizes faster, so less interest is at stake. However, if you hold the 15-year to term, the total interest saved from the rate reduction is significant.
30-Year Points
On a $300K 30-year at 7%: one point ($3,000) reduces to 6.75%, saving about $48/month. Break-even: 63 months. The savings are slightly higher and the loan term is longer, so the total interest saved over the life of the loan from buying points is much larger on a 30-year.
Break-Even Comparison
The break-even on both loan terms is similar (5-6 years), but the total savings over the full loan life is larger on a 30-year because you have more years of benefit. If you plan to keep the loan for 10+ years, points on either term can work. On a 15-year, the higher payment makes the upfront cost of points harder to absorb.