Help & Getting Started

Hand Calculations is a workspace of science & engineering calculators and unit converters. Add up to six to a page, run them, and — when signed in — save your layout. This guide covers finding calculators in the catalog, arranging your workspace, choosing units, and solving for any variable.

1 · Navigating the catalog

The Catalog is the panel on the left of the workspace. Everything you can add lives here, grouped into categories.

1. Search to jump straight to a calculator — type a name, category, or symbol and the tree filters as you type.
2. Browse by category. Click a category (e.g. Physics) to expand it, then a sub-category (e.g. Mechanics) to see its calculators. Empty categories are hidden.
3. Click load on any calculator to add it to your workspace.
4. Units are converters. Under Units, click convert to add a unit-converter card (Speed, Pressure, Temperature, and more).

2 · Arranging your workspace

Your workspace holds up to six cards in a grid. Each card is either a calculator or a unit converter. The card's name sits on its own row (with the × to close it in the top-right); a second row underneath holds the verification badge, a ? help button, and the reorder arrows. Here's what each control does:

1. Add cards from the catalog (up to six per page). Trying to add a seventh takes you to the second tab.
2. Reorder by dragging a card with its grip ⠿, or use the ← → arrows on the second row for one step at a time.
3. Edit values by clicking into a field and typing — the current value selects so you can replace it directly. Press Calculate (calculators) or change a unit (converters) to update the result.
4. Learn the formula with the ? button or the About this formula → link at the bottom of the card — both open a help page with the parameters, derivation, and the science & history behind it.
5. Remove a card with × (top-right) when you're done with it.

3 · Choosing units for any input or result

Every input that has a unit shows a small unit menu beside its value. Pick whatever unit your numbers are in — the calculator converts it under the hood, so the math is always correct. You can also choose the unit the result is shown in.

1. Click an input's unit menu and choose the unit your value is in. Only units that make sense for that quantity are offered.
2. Type your value in that unit — the conversion to the calculator's internal unit is automatic, so you never convert by hand.
3. Pick a result unit under Result in… to read the answer however you prefer.

4 · Solving for any variable

Normally a calculator takes the inputs and gives you the result — but you can also work backwards: fix the result you want and let the card solve for one of the inputs. Under each formula is a "Solve for:" row with one chip per variable.

1. Click a chip in the Solve for: row to choose which variable to find. Click it again (or the ✕) to return to normal.
2. Enter your target result in the box that appears — in any unit you like — and press Solve.
3. Read the answer in the variable's box, shown in your selected unit. If the formula rearranges cleanly, the rearranged equation also appears on the card.

5 · Saving your layout

1. Sign in (top-right) with an email and password, or create an account.
2. Click Save Layout under the catalog — your cards and their values are stored to your account.
3. Next time you sign in, your layout loads automatically. You can also click Load Layout to restore it.

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