#156
XA
Grok 1.5
xAI
19.3 LLMBoard
xAI model product
Pushing the Frontier of Cost-Efficient Intelligence. Grok-4 Fast Reasoning is a high-speed variant of Grok-4 optimized for faster inference while maintaining strong reasoning capabilities through thinking tokens.
Updated Aug 10, 2026. Default version: Grok-4 Fast Reasoning
Structured fields from the published default version.
This profile uses the latest version under this unique model that has a calculated LLMBoard score. Arena and price are excluded.
No published version under this unique model currently has enough benchmark coverage to calculate a score.
Published benchmark records for the scored version currently unavailable.
No published benchmark result is linked to the scored version.
Preference and agent-evaluation signals from published Arena datasets.
| text factuality | creative writing | 90 | 1400.3 | 787 | N/A | |
| text | french | 92 | 1433.5 | 266 | N/A | |
| text | industry legal and government | 95 | 1427.9 | 1,189 | N/A | |
| text factuality | industry writing and literature and language | 96 | 1402.3 | 1,425 | N/A | |
| text style control | french | 96 | 1441.9 | 266 | N/A | |
| text | japanese | 97 | 1355.3 | 176 | N/A | |
| text style control | spanish | 97 | 1412.7 | 520 | N/A | |
| text factuality | hard prompts english | 99 | 1453.2 | 1,792 | N/A | |
| text factuality | longer query | 99 | 1431.6 | 1,608 | N/A | |
| text factuality | industry life and physical and social science | 100 | 1440.3 | 939 | N/A | |
| text factuality | multi turn | 101 | 1422.4 | 1,068 | N/A | |
| text style control | japanese | 101 | 1366.1 | 176 | N/A | |
| text | spanish | 102 | 1411.1 | 520 | N/A | |
| text factuality | industry entertainment and sports and media | 102 | 1386.2 | 1,102 | N/A | |
| text | longer query | 106 | 1411.0 | 4,436 | N/A | |
| text factuality | instruction following | 106 | 1408.5 | 1,830 | N/A | |
| text factuality | coding | 107 | 1455.2 | 1,388 | N/A | |
| text factuality | industry business and management and financial operations | 107 | 1419.2 | 1,247 | N/A | |
| webdev | webdev-html | 108 | 1168.6 | 730 | N/A | |
| webdev | overall | 109 | 1159.8 | 730 | N/A | |
| webdev | webdev | 109 | 1159.8 | 730 | N/A | |
| text factuality | english | 110 | 1427.8 | 4,710 | N/A | |
| text style control | korean | 110 | 1354.5 | 342 | N/A | |
| text | korean | 111 | 1355.0 | 342 | N/A | |
| text style control | industry legal and government | 111 | 1426.1 | 1,189 | N/A | |
| text | industry medicine and healthcare | 112 | 1420.2 | 871 | N/A | |
| text style control | industry medicine and healthcare | 114 | 1435.1 | 871 | N/A | |
| text | industry life and physical and social science | 115 | 1423.5 | 2,986 | N/A | |
| text | creative writing | 116 | 1374.9 | 2,506 | N/A | |
| text | german | 116 | 1387.1 | 349 | N/A | |
| text factuality | overall | 116 | 1416.2 | 10,780 | N/A | |
| text style control | industry life and physical and social science | 117 | 1432.3 | 2,986 | N/A | |
| text style control | math | 118 | 1410.7 | 1,076 | N/A | |
| text factuality | industry software and it services | 119 | 1441.0 | 2,490 | N/A | |
| text factuality | non english | 119 | 1398.5 | 5,000 | N/A | |
| text | expert | 121 | 1406.9 | 864 | N/A | |
| text factuality | exclude ties | 121 | 1402.7 | 7,465 | N/A | |
| text | chinese | 122 | 1434.6 | 691 | N/A | |
| text | multi turn | 122 | 1405.0 | 3,067 | N/A | |
| text style control | creative writing | 122 | 1381.2 | 2,506 | N/A | |
| text style control | german | 122 | 1386.8 | 349 | N/A | |
| text | coding | 123 | 1418.9 | 3,945 | N/A | |
| text | polish | 123 | 1379.5 | 731 | N/A | |
| text | russian | 123 | 1390.5 | 1,038 | N/A | |
| text factuality | hard prompts | 124 | 1428.8 | 5,389 | N/A | |
| text style control | chinese | 124 | 1442.1 | 691 | N/A | |
| text | industry entertainment and sports and media | 125 | 1366.5 | 3,315 | N/A | |
| text | industry writing and literature and language | 126 | 1379.8 | 4,174 | N/A | |
| text style control | russian | 126 | 1399.5 | 1,038 | N/A | |
| text | hard prompts english | 127 | 1414.9 | 5,188 | N/A | |
| text | industry business and management and financial operations | 127 | 1392.7 | 3,652 | N/A | |
| text style control | industry writing and literature and language | 127 | 1387.6 | 4,174 | N/A | |
| text | math | 129 | 1402.9 | 1,076 | N/A | |
| text style control | multi turn | 129 | 1406.6 | 3,067 | N/A | |
| text style control | polish | 129 | 1380.3 | 731 | N/A | |
| text | instruction following | 130 | 1381.9 | 5,300 | N/A | |
| text style control | industry mathematical | 130 | 1411.3 | 935 | N/A | |
| text style control | longer query | 130 | 1411.5 | 4,436 | N/A | |
| text style control | non english | 130 | 1390.5 | 9,352 | N/A | |
| text style control | overall | 131 | 1404.0 | 18,688 | N/A | |
| text style control | exclude ties | 131 | 1387.3 | 13,213 | N/A | |
| text | exclude ties | 133 | 1377.4 | 13,213 | N/A | |
| text | non english | 133 | 1385.2 | 9,352 | N/A | |
| text | overall | 134 | 1398.0 | 18,688 | N/A | |
| text | industry software and it services | 134 | 1413.1 | 6,767 | N/A | |
| text | hard prompts | 135 | 1403.4 | 9,889 | N/A | |
| text | industry mathematical | 135 | 1399.6 | 935 | N/A | |
| text style control | english | 135 | 1413.7 | 9,288 | N/A | |
| text style control | expert | 135 | 1416.9 | 864 | N/A | |
| text | english | 136 | 1407.1 | 9,288 | N/A | |
| text style control | industry business and management and financial operations | 137 | 1401.1 | 3,652 | N/A | |
| text style control | industry entertainment and sports and media | 137 | 1367.4 | 3,315 | N/A | |
| text style control | instruction following | 137 | 1388.3 | 5,300 | N/A | |
| text style control | coding | 144 | 1437.4 | 3,945 | N/A | |
| text style control | hard prompts english | 145 | 1423.5 | 5,188 | N/A | |
| text style control | industry software and it services | 148 | 1426.0 | 6,767 | N/A | |
| text style control | hard prompts | 150 | 1412.8 | 9,889 | N/A |
Official vendor API PAYG pricing is summarized first. The table then lists individual provider offerings without treating their minimum as the official price.
| Jiekou.AI | grok-4-fast-reasoning | global | $0.18 | $0.45 | 2M | |
| Helicone | grok-4-fast-reasoning | global | $0.20 | $0.50 | 2M | |
| Poe | xai/grok-4-fast-reasoning | global | $0.20 | $0.50 | 2M | |
| 302.AI | grok-4-fast-reasoning | global | $0.20 | $0.50 | 2M |
Official prices use only the vendor's configured official Provider and positive standard USD PAYG rates. Third-party offers remain explicitly labeled.
All published versions linked to this unique model. The score columns identify the version used by the current overall ranking.
| Grok-4 Fast Reasoning | N/A | N/A | 2M | 30K | No | Proprietary |
A concise description based on the published model registry.
Pushing the Frontier of Cost-Efficient Intelligence. Grok-4 Fast Reasoning is a high-speed variant of Grok-4 optimized for faster inference while maintaining strong reasoning capabilities through thinking tokens.
Use the benchmark, Arena and pricing sections above as separate evidence. A missing field means the current data snapshot does not support that claim.
Data snapshot: 2026-08-07. Editorial model content is not available in the backend.
Recommendations prioritize the same model type and family, then the closest published LLMBoard score.
Common questions about Grok 4 Fast Reasoning.
Grok 4 Fast Reasoning's default version was released on Aug 28, 2025.
No official standard PAYG price is currently available for Grok 4 Fast Reasoning. The lowest tracked third-party offer starts at $0.18 input and $0.45 output via Jiekou.AI.
Grok 4 Fast Reasoning is published under xAI in the model registry.
The default version has a 2M token context window.
No. The default version is not marked as having publicly available weights.
4 published provider offerings are linked to the default version.
No nearby ranked alternatives are currently available.