Lumen AI engines — Fast, Professional, Expert & Ultra

Pick an engine

Choose an engine to see what it does in each tool.

Select any engine below — the list underneath updates to show how that engine helps in every document type.

Lumen Fast The dozens of small asks in a normal day. Answers land almost immediately and cost the fewest credits. Free and up Lumen Professional Real document work. It holds a long file in mind and follows multi-part instructions, so the first draft is usually the one you keep. Plus and up Lumen Expert Work that has to be reasoned through. It thinks before answering and checks its own output, then fixes what it got wrong. Pro on demand · always from Max Lumen Ultra The hardest work you have. Our most capable engine at maximum reasoning depth, so complex jobs finish correctly in one pass. Ultra plan only

Lumen Fast — Quick everyday help, in placeBest when you already know what you want and just want it done now.

Lumen PDFAsk what a clause means, summarize a page, pull out the dates, names and totals you need right now.Answer in seconds Lumen DocumentTighten a paragraph, fix the tone, generate headings and a summary for a draft you already wrote.Fewest credits Lumen SheetsExplain what a formula is doing, label a messy column, normalize inconsistent text values.Instant cleanup Lumen SlidesRewrite a bullet, shorten a title so it actually fits, write the speaker notes for a finished slide.Per-slide polish Lumen DesignWrite the caption, trim a headline to the frame, name and tidy layers on a busy board.Copy on demand Lumen NotesTurn a raw meeting note into clean bullets and pull the action items out of it.Notes to bullets Lumen FormsDraft the question wording, fix confusing labels, write the confirmation message.Wording, fast Lumen AutomateName a step, describe what a run actually did, map fields between two apps.Keeps runs readable Lumen AgentSingle-tool errands — find the file, rename the batch, answer the one-line question.Cheapest to run

Lumen Professional — The draft you actually keepBest when the whole document is the unit of work, not one paragraph of it.

Lumen PDFTurn a 90-page agreement into a structured brief, and lift every table into a sheet with the columns typed correctly.Whole file at once Lumen DocumentDraft the entire proposal from your notes and outline — your structure, your voice, ready to edit.Full first draft Lumen SheetsBuild a working model: formulas, named ranges, a pivot, and the chart that actually explains it.Model, not cells Lumen SlidesTurn an outline or an existing document into a complete deck with real content on every slide.Deck from a doc Lumen DesignCompose a real layout — hierarchy, spacing, type pairing and your brand colours applied across the board.Designed, not placed Lumen NotesTurn a recorded meeting into a structured summary with decisions, owners and dates separated out.Recording to record Lumen FormsBuild the whole form — the right question types, validation, and branching that follows the answers.Form in one pass Lumen AutomateAssemble a multi-step automation that runs across a whole folder and produces the report at the end.Runs at scale Lumen AgentMulti-step jobs that cross two or three tools and land in the right files.Handles handoffs

Lumen Expert — Thinks first, then checks itselfBest when being wrong is expensive and you need the reasoning, not just the answer.

Lumen PDFCompare two contract versions clause by clause and tell you what genuinely changed — and why it matters.Catches the diff Lumen DocumentAudit a long document for contradictions, gaps and unsupported claims before it goes out.Reviews before you send Lumen SheetsTrace a broken model back to the cell that caused it, and sanity-check the logic rather than the syntax.Finds the real bug Lumen SlidesCritique the deck’s argument and re-sequence it so the story actually lands.Fixes the narrative Lumen DesignLooks at what it made, judges it and fixes it — the vision loop behind image generation and the deep design passes.Sees its own work Lumen NotesSynthesize a dozen scattered notes into one reasoned position, with the open questions called out.Reasoned synthesis Lumen FormsPressure-test a survey for leading questions and bias before you publish it to real people.Bias check Lumen AutomatePlan the automation, reason about what could fail, and self-correct part way through a run.Recovers mid-run Lumen AgentLonger autonomous runs with checkpoints, self-review and a plan you can read first.Reviews as it goes

Lumen Ultra — Maximum depth, one passBest when the brief is ambiguous and deciding what to do is harder than doing it.

Lumen PDFDense technical and legal analysis across a whole stack of documents held in mind together.Many files at once Lumen DocumentAmbiguous briefs, where working out what should be written is the hard part.Decides the shape Lumen SheetsLarge interdependent models, where a wrong assumption three steps back is the actual problem.Follows the chain Lumen SlidesA board-level narrative argued end to end and built from scattered evidence.Argues the case Lumen DesignArt direction with taste — a coherent visual system, not a set of individually pretty frames.System, not frames Lumen NotesResearch-grade synthesis across an entire notebook, with the reasoning shown.Whole-notebook recall Lumen FormsInstrument design, where the questions themselves decide the quality of the data you get back.Designs the instrument Lumen AutomateLong, branching automations that have to finish correctly while nobody is watching.Unattended and correct Lumen AgentThe long autonomous runs — many files, many tools, finished in a single pass.Goes the distance

How the work gets made

Every run follows the same five steps.

This is the loop behind every Lumen result — the reason the output is something you can use rather than something you have to check line by line.

Gather

Plan

Create

Review

Enhance

Working on it

Gather Plan Create Review Enhance

Gathers everything firstReads the document you are in, the references you attached, your library across every tool, what it remembers from previous work — and the web when you allow it.
Writes the plan before touching anythingDecides what to change, in what order, and what finished looks like — then shows you the plan, so nothing happens to your file until it makes sense.
Does the work in the real documentUses each editor’s own tools on the actual file — real text in the PDF, real formulas in the sheet, real layers on the board. Never a copy pasted back in.
Looks at what it producedRenders the result and reads it back, then checks it against the plan and the source — catching the things that look right in a draft and are wrong in the file.
Fixes and lifts it a levelCorrects what the review found and takes one more pass at quality, so what you get back is finished work rather than a first attempt you have to repair.

Every engine runs this loop. Deeper engines spend more of it on steps 4 and 5 — which is exactly what you are paying for when you move up.

At a glance

The whole ladder, side by side.

Credits are cost-based, so a deeper engine simply uses more of your monthly allowance per step — you are never charged a different rate.

	Fast	Professional	Expert	Ultra
Best for	Quick everyday asks	Whole-document work	Work that must be reasoned	The hardest, most ambiguous work
Reasoning depth	Direct answer	Deep context	Extended thinking	Maximum thinking
Checks its own work	—	—	✓	✓
AI image generation	—	—	✓	✓
Powers Lumen Automate	—	—	✓	✓
Credits per step	Lowest	Low	Higher	Highest
Included with	Every plan, free	Plus and up	Pro (on demand) · Max (always)	Ultra

How to choose

You rarely have to think about this.

Every plan has a sensible default engine, and the assistant picks it for you. Change it per editor whenever a job deserves more depth.

A default that fits the plan

Free runs on Fast, Plus on Professional, Max on Expert and Ultra on Ultra. You get your plan’s best engine without choosing anything.

Switch it per editor

From Plus up, the engine picker sits in every editor’s AI panel. Use a deeper engine for the one hard task without changing anything else.

Pay only for what you use

One shared monthly credit allowance covers every engine and every tool. A deeper engine uses more credits per step, and nothing else changes.

FAQ

Engine questions, answered.

Do I have to pick an engine every time?

No. Each plan has a default engine and the assistant uses it automatically. The picker is there for the moments when one particular task deserves more depth than your usual default.

Does a deeper engine cost more money?

Not a different rate — credits are priced from what a request actually costs to serve, so a deeper engine simply uses more of your monthly allowance per step. Your plan price does not change.

Can I use a deeper engine on a smaller plan?

Engine access is set by your plan: Free includes Fast, Plus adds Professional, Pro unlocks Expert on demand, Max makes Expert the default, and Ultra unlocks Lumen Ultra. You can change plans at any time.

Which engine does Lumen Agent use?

The Agent uses your plan’s engine too. Deeper engines matter most here, because an autonomous run makes many decisions in a row and each one compounds.

Do my documents get used to train these models?

No. Your content is sent only when you ask for an AI action, only the content needed for that action is sent, and it is never used to train models. See Security for the details.

Four engines. One for every kind of work.