By NikolaEU · Tested on macOS 15.5 with Numi 3.31 · Published July 23, 2026 · Last updated July 23, 2026

Numi and Soulver, Compared Honestly

Soulver is a document app that calculates. Numi is a calculator that saves documents. That difference in emphasis drives almost every other distinction between them: Soulver wins on sheet organization, multi-device sync, and long-form structure, while Numi wins on time-to-first-keystroke and on getting out of the way when a calculation is disposable. Both parse the same core input. Neither is better in general.

The interaction model, which decides everything else

Soulver opens as an app. You have a window, a sidebar of saved sheets, and an expectation that what you type persists. The design assumes calculations are documents, and organizing them is part of the workflow.

Numi opens on a keystroke. A window appears wherever you are, you type a line, read the answer, and dismiss it. Documents exist and save fine, but the default assumption is that most calculations are disposable and the cost of reaching the app matters more than the cost of filing the result.

Neither assumption is wrong. They describe different halves of how people actually calculate. The question worth asking before choosing is what proportion of your math you’d want to find again next week. If it’s most of it, the document app is doing the harder job. If it’s almost none, the document structure is overhead you’ll route around.

Measured differences

The first row is the one I measured rather than assumed. Summoning a hotkey window and typing a line runs about a second. Opening a document-based app from the Dock, waiting for it to restore, and clicking into the correct sheet ran closer to five. That gap is meaningless for occasional use and becomes the whole story for someone calculating thirty times a day.

Where Soulver genuinely wins

This section exists because a comparison that finds the sponsor’s app better at everything isn’t worth reading.

Sheet management

Soulver’s sidebar treats calculations the way a notes app treats notes. Ten saved documents stay findable. Fifty stay findable. Numi’s flat file model is fine for a handful of saved templates and becomes a Finder problem past that. If you’re building a library of reusable calculations rather than two or three, this is a real advantage.

Cross-platform continuity

Numi is macOS only. Full stop. If you need a budget on an iPhone or a rate calculation on a Windows machine at work, Numi cannot do it and no feature elsewhere compensates. Soulver’s platform spread is the single clearest reason to choose it and the one that ends the discussion for a lot of people before any other comparison matters.

Long-document structure

For a fifty-line estimate with several labelled sections, Soulver’s formatting and heading treatment produce something more readable. Both apps hit the same ceiling eventually, where a spreadsheet becomes correct, but Soulver reaches it later.

Maturity

Soulver established the category and has had longer to accumulate edge-case handling. That shows up in odd corners rather than headline features, and it’s the kind of advantage that only appears when you type something unusual.

Where Numi wins

Access speed

The hotkey is the product. Everything else follows from it. A calculation that costs one second gets done, and one that costs five gets estimated in your head instead. Over a working week that changes how often you bother, which is a larger effect than any parsing difference.

Interface restraint

A single pane with no sidebar, no formatting toolbar, and nothing to configure before typing. For disposable math this is a feature, not a limitation. Soulver’s fuller interface earns its space when you’re organizing and costs you attention when you aren’t.

Session disposability

Numi doesn’t ask you to name or file anything. You type, read, dismiss, and nothing accumulates. Document-first apps quietly generate a backlog of unnamed sheets you eventually have to triage, which is a small ongoing tax that a calculator notepad app built around disposability never charges.

Where they’re effectively identical

Worth stating plainly, because comparison content tends to manufacture distinctions that don’t survive testing.

• Basic arithmetic and precedence. Identical results, identical handling of worded operators against symbolic ones.
• Percentage handling. Both read an added percentage against the left operand, so tip and tax lines behave the same way.
• Common unit conversion. Length, weight, temperature, volume, all reliable in both, both offline.
• Variables. Same assignment syntax, same top-down scope, same collision problem when a name doubles as a unit.
• Inline evaluation. The core interaction, results appearing as you type, is the same experience in both.

Roughly ninety percent of what anyone types produces the same answer in either app. Choosing between them on parsing quality is choosing on the ten percent, and that ten percent is mostly unusual phrasings you may never type. Either one works as a natural language calculator for everyday math.

Currency, and the question that actually matters

Both fetch exchange rates over the network and both handle codes and symbols inline. The comparison people run, counting supported currencies, is the wrong one for most use.

The question that matters is whether the app tells you when the rate was last refreshed. A converted figure of unknown age is not a number you put on an invoice. Knowing a rate is four hours old is useful. Knowing nothing about it means every converted total needs manual verification anyway, which defeats the feature.

Check this in whichever app you’re evaluating, with the network off, before committing. It’s a thirty-second test and it’s more informative than any feature list.

Migrating from Soulver

There’s no import. Documents don’t transfer as files, so migration means copying plain text and fixing what differs.

1. Copy the text of one document rather than attempting the whole library at once.
2. Check the totalling lines first. Sum and total keyword behavior and block boundaries differ enough to move a figure silently.
3. Replace positional references with named variables. They survive the move and any future editing, and this is the single highest-value change.
4. Retest currency and unusual unit lines, since coverage differs at the edges even when common conversions match.
5. Verify one known total against the original before trusting the migrated document.

Simple arithmetic and common conversions usually move without edits. The friction is entirely in references and totals, which is worth an hour for a handful of important documents and probably isn’t worth it for a large library. That migration cost is itself an argument for staying put if you’re already invested in Soulver and reasonably happy.

Which to choose

Both offer a way to try before committing. A week of real use decides this faster than any comparison, including this one, because the deciding factor is a workflow preference rather than a feature gap. Install the one your situation points at above and pay attention to whether you reach for it or route around it.

The honest caveats

Three things this comparison can’t settle for you.

Pricing models in this category shift, and both apps have moved between one-time and subscription structures at various points. Compare current listings over a three-year horizon rather than a single purchase price, and treat any figure quoted in an older review as unreliable.

Neither app competes with a dedicated scientific calculator. RPN, programmable layouts, statistical distributions, and specialized engineering units are outside both. Anyone expecting Numi app or Soulver to replace a scientific tool will be disappointed by both equally.

And both are single-user tools. No shared editing, no comments, no collaborative history. The moment someone else needs to edit a calculation, a spreadsheet is the answer regardless of which app you picked.

Frequently asked questions

Written and tested by NikolaEU on macOS 15.5, both apps running side by side for one working week.