About Zone Light Meter
A precise, beginner-friendly analogue light meter app for iPhone and Android. Built for film photographers who want a meter that fits in their pocket, works offline, and explains every reading it gives.
What it is
Zone Light Meter turns your phone into a calibrated handheld light meter for film photography. It reads light through your phone's camera, calculates aperture and shutter settings, accounts for the quirks of analogue film (reciprocity failure, bellows extension, IR filters, expired stock), and logs every shot so you can match it back to a scan or contact sheet later.
What makes it different
Most light meter apps stop at the reading. This one is designed around a specific belief: that the meter should teach you. Every modal has a help icon. Every recommendation explains what it is doing and why. The zone system, the sunny 16 rule, reciprocity crossovers, hyperfocal distance, multi-spot biasing: all of it is spelled out in plain language, with the math available if you want to see it.
Local-first and private
There is no account. There is no cloud sync. There are no third-party trackers. Every reading, every roll, every shot you log lives in a database on your phone, which you can export to CSV at any time. The app works fully offline. The website you are reading uses cookie-free Cloudflare Web Analytics for aggregate page counts only; the privacy page has the full story.
Frequently asked
Is Zone Light Meter free?
Yes. Free on iPhone and Android, no ads, no account, no subscription.
Who builds Zone Light Meter?
One developer working in their spare time, between rolls of film. Email contact is on the support page.
Is there an iPhone version?
Yes. The iPhone version came out in November 2026 and is free on the App Store. It needs iOS 17 or later and has the same metering, Zone System tools, film catalogue and shot log as the Android app.
How is this different from other light meter apps?
Zone Light Meter is designed around the Zone System with multi-spot biasing, false-color HDR, a 674-stock film catalogue, and first-class corrections for reciprocity, bellows, IR filters, and expired film. Every modal explains itself in plain language.
The documentation
This site documents 123 features across 20 sections. Of those, 116 are fully shipped, and 7 are partially shipped. Each feature has a page that explains what it does, when to use it, and where to find it in the app.
The documentation is generated from the same data source the app itself reads to render its in-app help modals. If a feature changes in the app, the page you are reading also changes. Nothing drifts.
Who builds it
One developer, working in their spare time, between rolls of film. Feedback is welcome. The email is on the support page.
Platform availability
Android came first, because its camera APIs were the right place to build the metering pipeline. The iPhone version followed in November 2026 and needs iOS 17 or later. Both are free: App Store and Google Play. The two apps share the same features, so the docs on this site apply to either phone. Screenshots are taken on Android, which is why the odd system bar or button may look slightly different from what you see on an iPhone.