Best LLM for Reasoning & Math (2026)
Hard math, planning and multi-step logic are where reasoning models earn their premium. They "think" before answering, which means more output tokens — so cost depends heavily on output price.
Top picks, with price
1. GPT-5.5 · OpenAI
Top-tier reasoning for the hardest problems, with adaptive thinking built in.
$5.00 in
$30.00 out
400K ctx
2. DeepSeek-V4 Pro · DeepSeek
Open-weight reasoning (thinking mode) at a fraction of the cost — the value pick for math and logic.
$0.435 in
$0.870 out
128K ctx
3. GPT-5.4 mini · OpenAI
Cost-efficient reasoning that handles most STEM tasks for a fraction of the flagship.
$0.750 in
$4.50 out
400K ctx
What to watch out for
- Reasoning models emit hidden "thinking" tokens you still pay for — budget by output price, not input.
- For simple tasks a reasoning model is wasteful; route only hard prompts to them.
Run your own numbers in the cost calculator, or browse the full price comparison.