FishRuler: Fish Size MeasureSupport
Questions or bug reports about FishRuler (fish size measuring and catch logbook)? Please take a look at the FAQ below, then feel free to email us. If measuring isn't working at all, the first thing to check is whether your iPhone has a LiDAR scanner.
FAQ
Which iPhones does it work on?
FishRuler measures with the LiDAR scanner, so it needs an iPhone that has one. That means the Pro models: iPhone 12 Pro / Pro Max and later. On a device without LiDAR you'll see "This device does not support LiDAR" and measuring won't be available. Please check your model before buying.
Do I need to update iOS to use it?
Yes — FishRuler requires iOS 17 or later, since the logbook is built on Apple's newer on-device storage framework. If your iPhone can't update to iOS 17, the app won't install. Most LiDAR-capable iPhones can run iOS 17 without issue, but it's worth checking your software version before buying.
How do I use it?
Point the camera at the fish, tap once at the nose and once at the tail. A line is drawn between the two points and the distance appears in centimeters. If a tap is off, drag the marker to fine-tune it, and press Reset to clear the measurement for the next fish.
Are my measurements saved? Can I look back at old catches?
Yes. When you save a measurement, it goes into your logbook along with a photo, species, location name, and date, so you can browse past catches any time. Nothing is saved automatically — you choose which measurements to log.
How does the personal best feature work?
Whenever you log a catch, FishRuler compares its length against the other entries you've logged for that species and marks it if it's your longest yet. It's based only on what you've logged in your own logbook, not on any outside database.
Where does the release-size reference info come from?
It's drawn from a small set of publicly published regulations — for example, national freshwater fishing rules and shared regional conservation sizes — for species and areas we could clearly document. It's shown purely as a reference alongside your measurement, not as an official ruling, and it isn't available for every species or region. Always check the current rules that apply where you're fishing.
How accurate is the number?
The value on screen is an estimate based on what your device's depth sensor actually measures. You'll get steadier results in good light, with a steady hand, and with the fish laid as flat as you can manage. Treat it as a practical figure for use on the water.
Can I use it for tournament measuring or size limits?
Please don't use it for that. For tournament measuring rules, legal size limits, or official record submissions, always confirm with the measuring device the rules require. Checking the regulations that apply where you fish is up to you as the angler.
Does it work where there's no signal?
Yes. FishRuler runs completely offline. Rocky shorelines, mountain streams, jetties, offshore on the boat — it measures just the same with no service.
Is there a fee? Is it a subscription?
It's a one-time purchase. Buy it once and there's nothing more to pay. No subscription, no in-app purchases, no ads.
Are my photos or measurements sent anywhere?
No. Your logbook — photos, species, lengths, locations, and notes — is stored only on your device. Nothing is sent to us or to any outside server, there's no account to sign in to, and the only time an image leaves your phone is if you personally choose to share a catch card.