Take the reference off the screen.
The whole reference - 252 formulas, every calculator, the constants, the converter and your own notes - is free and always will be. Premium adds the paper and the workout: 8 printable formula sheets, a builder for your own, and practice on the topics you choose with per-topic accuracy. Your data never leaves this browser.
- 8 printable formula sheets - 363 rows of equations, symbol keys and SI units, laid out for paper with repeating headers and page breaks between topics
- Build your own sheet from any of the 252 formulas - pick by category, by search or straight from your bookmarks, up to 60 on one page. Free lays out the first 8 rows in the real format so you can judge it before deciding
- Practice rounds on the topics and question types you choose, freshly shuffled every time, drawn from all 252 formulas across 6 categories. Free gets today's 10 question round, the same one for everybody, retakeable as often as you like
- Practice accuracy broken down by topic, so you know what to revise, plus your last 50 rounds rather than the last 3
- Everything else stays free and unlimited: 252 formulas, every formula calculator, 27 constants, 14 unit categories, search, saved formulas and your private per-formula notes
- One-time or subscription - study your way
Choose a plan
Weekly, yearly and lifetime plans are available - current prices load in the cards below.
Free vs Premium
The line is the format, not the physics. Nothing a paying reader can see is a fact a free reader cannot.
| What you get | Free | Premium |
|---|---|---|
| All 252 formulasEquations in real maths, every symbol defined, derivations | Included | Included |
| Every calculatorNo daily cap, no reveal step, no sign-up | Included | Included |
| 27 constants and 14 unit categoriesCODATA values, SI units, deep-linkable conversions | Included | Included |
| Search, bookmarks, study guides and notesEverything kept in your own browser | Included | Included |
| Today's 10 question practice roundThe same round for everybody, retakeable as often as you like | Included | Included |
| 8 printable formula sheets363 rows laid out for paper - repeating headers, breaks between topics. Free sees a real sample of every sheet | Not included | Included |
| Custom sheet builderUp to 60 formulas you pick on one printable page. Free lays out the first 8 rows in the real format | Not included | Included |
| Practice on your own topicsChoose topics and question types, freshly shuffled every round. Free gets today's shared 10 question round | Not included | Included |
| Per-topic accuracy and full historyAccuracy broken down by topic, and your last 50 rounds. Free keeps the headline totals and the last 3 | Not included | Included |
Questions
What stays free?
Every formula page with full KaTeX rendering, every category, all 27 physical constants, 14 categories of unit conversion, search, saved formulas and your private per-formula notes are free forever - no account needed. So is every one of the 252 formulas' calculators, with no daily limit, and today's 10 question practice round, retakeable as often as you like. PhysRef used to meter calculator runs at three a day and charge for the notes field; both of those are gone.
What exactly does Premium unlock, then?
4 things, all of them off the reference pages: the 8 printable formula sheets at /sheets (363 rows typeset for paper, headers repeating on every printed page, breaks falling between topics), the custom sheet builder that lays out up to 60 formulas you pick onto one page, practice rounds on the topics and question types you choose instead of the shared daily one, and per-topic accuracy with your last 50 rounds instead of 3. Premium buys the format, the selection and the tracking, never the physics: every equation on a sheet and every answer in a round is free to read on its own formula page, and a real sample of each sheet and builder layout renders for everyone.
How is my access stored?
Purchases are handled by RevenueCat and Stripe. An anonymous purchase id is kept in this browser so PhysRef recognises your Premium access on this device. Keep your receipt email for recovery.
I already subscribed on another browser or device - how do I get Premium here?
Head to Restore access and paste the access code shown on this Premium page (or from your receipt). Premium moves to this browser instantly.
Can I cancel?
Yes. Subscriptions renew automatically and can be cancelled anytime from the link in your receipt email. Lifetime is a one-time payment.
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Your code is shown on this page whenever you're subscribed here, and it's included in your purchase receipt email. If you can't find it, reply to your receipt email from the address you paid with - your subscription is tied to it and access can be recovered from there.