Personal AI assistant for a founder: what it costs and which AI to use
Day-to-day chat for drafting, thinking things through, research and planning, for one person. Solo founders and freelancers deciding between a flat monthly plan and paying per use.
The short answer
At 1,500 messages a month, we estimate $0.478 on DeepSeek V4 Flash 0423 (the cheapest model that cleared our quality bar), $5.68 on Kimi K2.6, and $45.94 on GPT-5.5. The flagship costs 8.1x the middle pick. Judged on reasoning, summarising and rewriting tasks: general helpfulness across mixed work.
Simulate your personal AI assistant for a founder
Pick a job, set how much of it you do, and see what every model would cost. Defaults are typical, not yours. Change them.
Prompt, history, documents
What the model writes
Advanced: caching, reasoning, retries, discounts
Share that can use cached-input prices where a model offers them
1 = none. 2 = hidden thinking doubles billed output
Extra calls on top of the base count
Batch jobs or committed spend. Check your provider; we assume none by default
Only used to compare with per-seat plans
Lowest benchmark score a model can have and still be picked. Higher is stricter.
Limit to certain providers
Untick any provider you cannot use, for data-residency, contract or policy reasons. Picks are recalculated.
1,500 messages a month, three ways to pay
Every model here cleared a score of 9.0 out of 10 on our reasoning, summarise, rewrite benchmark tasks, ran without errors and fits a 16K-token window. 16 of 386 priced models qualify.
Cheapest model that clears the bar.
DeepSeek V4 Flash 0423
- Per message
- $0.0003
- Benchmark
- 9.56 / 10 · 9 prompts
- Context
- 1.05M tokens
Priced near the middle of the models that clear the bar; best score there.
Kimi K2.6
- Per message
- $0.0038
- Benchmark
- 9.56 / 10 · 9 prompts
- Context
- 262K tokens
What many people reach for first.
GPT-5.5
- Per message
- $0.031
- Benchmark
- 9.56 / 10 · 9 prompts
- Context
- 1.05M tokens
Choosing GPT-5.5 over Kimi K2.6 costs $40.26 more a month, $483 a year (8.1x the price).
Both scored 9.56 out of 10 on this kind of work. The extra money buys safety margin our benchmark cannot measure: it is 24 short prompts, and most passing models score near the top. If a wrong answer is costly for you, that margin can be worth it. Test on your own data before you decide.
If it grows
Pay-per-use cost scales in a straight line. Monthly cost at 1x, 3x, 10x and 100x today's volume.
| Model | 1x · 1,500 | 3x · 4,500 | 10x · 15K | 100x · 150K |
|---|---|---|---|---|
| DeepSeek V4 Flash 0423 | $0.478 | $1.43 | $4.78 | $47.78 |
| Kimi K2.6 | $5.68 | $17.04 | $56.80 | $568 |
| GPT-5.5 | $45.94 | $138 | $459 | $4,594 |
What a budget buys
- DeepSeek V4 Flash 0423314Kmessages a month, about 10K a day
- Kimi K2.626Kmessages a month, about 880 a day
- GPT-5.53,265messages a month, about 108 a day
Or a flat monthly plan
When people use the output directly, a per-seat plan can beat paying by the token. Plans have usage caps that change, so check the current limits.
- Google AI Plus$4.99 a monthPaying per use on Kimi K2.6 costs the same above about 1,318 messages a month. You do 1,500, so the flat plan is cheaper at these numbers.
- ChatGPT Go$8.00 a monthPaying per use on Kimi K2.6 costs the same above about 2,112 messages a month. You do 1,500, so per-use is cheaper at these numbers.
- Rytr$9.00 a monthPaying per use on Kimi K2.6 costs the same above about 2,377 messages a month. You do 1,500, so per-use is cheaper at these numbers.
- Google AI Pro$19.99 a monthPaying per use on Kimi K2.6 costs the same above about 5,279 messages a month. You do 1,500, so per-use is cheaper at these numbers.
Every model, priced for your workload
41 models, 11 hidden because their window is smaller than 16K tokens.
| Model | A month | Per message | Benchmark | Context |
|---|---|---|---|---|
| DeepSeek V4 Flash 0423 DeepSeekBudget pick | $0.478 | $0.0003 | 9.56 (9) | 1.05M |
| Ministral 3 8B 2512 Mistral AIbelow the bar | $0.591 | $0.0004 | 6.44 (9) | 262K |
| DeepSeek V4.1 Flash DeepSeekbelow the bar | $0.690 | $0.0005 | 7.89 (9) | 1.05M |
| Llama 4 Scout Metabelow the bar | $0.722 | $0.0005 | 7.89 (9) | 1.31M |
| Qwen3.8 Flash Alibaba | $0.929 | $0.0006 | 9.33 (9) | 1M |
| GLM 5.3 Flash Z Aibelow the bar | $0.998 | $0.0007 | 8.44 (9) | 1.05M |
| Mistral Small 4 Mistral AIa benchmark run failed | $1.06 | $0.0007 | 9.63 (8) | 262K |
| MiniMax M2.5 Minimax | $1.79 | $0.0012 | 9.44 (9) | 205K |
| GLM 5.3 Z Ai | $1.83 | $0.0012 | 9.67 (9) | 1.05M |
| GPT-5.4 Nano OpenAI | $1.89 | $0.0013 | 9.56 (9) | 400K |
| Muse Glimmer 30B Metabelow the bar | $2.15 | $0.0014 | 8.89 (9) | 131K |
| MiniMax M2.7 Minimax | $2.21 | $0.0015 | 9.44 (9) | 205K |
Benchmark = mean judge score out of 10 on the reasoning, summarise, rewrite prompts of the Model Playground, with the number of prompts in brackets. Models marked n/a have no benchmark run, so we do not guess their quality. How the benchmark works.
What we assumed
- About 50 messages a day, 30 days a month: 1,500 messages.
- Each message sends the chat so far plus new text, about 3,500 tokens.
- Each reply is about 500 words, roughly 700 tokens.
- Half of the input repeats between turns.
These are typical numbers, not measurements of your business. Edit them in the simulator above.
What drives the cost
Light use is nearly free by the token, so the real question is whether a flat plan is ever worth it.
Watch out for
- A flat plan also gives you apps, file uploads, voice and image tools that the raw API does not.
- Usage caps on flat plans vary and change often. Check the plan's current limits before relying on it.
Questions people ask
How much will personal AI assistant for a founder cost per month?
At 1,500 messages a month, we estimate $0.478 a month on DeepSeek V4 Flash 0423, the cheapest model that clears our quality bar for this job. Kimi K2.6 costs $5.68 and GPT-5.5 costs $45.94. These are estimates from the assumptions listed on this page, not a quote. Change the numbers to match your own volume.
What is the cheapest AI model for personal AI assistant for a founder?
On current OpenRouter prices, DeepSeek V4 Flash 0423 from DeepSeek is the cheapest model that cleared our bar of 9.0 out of 10, scoring 9.6/10 on 9 benchmark prompts for this kind of work. The benchmark is small, so treat it as a shortlist and test on your own data before switching.
Is it worth paying for a flagship model for personal AI assistant for a founder?
On our benchmark, GPT-5.5 scored 9.6/10 on this kind of work, and a model priced near the middle of the models that cleared the bar, Kimi K2.6, scored 9.6/10, while the flagship costs 8.1x as much. A flagship buys safety margin the benchmark cannot measure. If a wrong answer is expensive for you, that can be worth paying for. If not, you are probably overpaying.
What happens to the cost if personal AI assistant for a founder grows ten times?
Pay-per-use pricing scales in a straight line, so ten times the messages is ten times the bill. Use the growth table on this page to see 3x, 10x and 100x for the same three models.
What makes personal AI assistant for a founder expensive?
Light use is nearly free by the token, so the real question is whether a flat plan is ever worth it.
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