Rebar counting app, free in your browser

A rebar counting app with nothing to install

This rebar counting app runs in your phone's browser. Open the page on site, photograph the cut ends of a bundle and it rings every bar it counts. It is free, with no sign-up and no daily limit, and it works on Android phones as well as iPhones. The photo is counted on your phone and never uploaded.

It uses the round-ends model, the same one behind the pipe counter. The model was trained on photos of rebar bundle ends as well as pipe bundles, dense bundles included.

What it counts, and what it doesn't

It counts the ends of round bars in a bundle or a rack, seen end-on: rebar, steel bars and TMT bars, round bar, dowels and threaded rod.

It does not count:

• Rebar already placed, such as mats or mesh on a deck, or bars tied into a cage. It needs the ends facing the camera.
• Bent shapes, stirrups and coils. They don't show a neat face of cut ends to the camera.
• How many bars a slab needs. That is a job for a rebar calculator. This counts the bars in front of you.

How to photograph a rebar bundle

1. Face the cut ends straight on. Stand square to the bundle. From an angle, the front bars hide the ones behind.
2. Pick the flush end. Bars in a bundle are rarely cut to exactly the same length. Photograph the end where they are most even, so no bar sits deep in the shadow of its neighbours.
3. Move tags and tie wire aside if they cover any ends.
4. Get close. A bundle of thin bar can hold hundreds of ends, and from a few metres away each one is a speck. Each end should be a clear dot. If you can't get close and still fit the whole bundle in the frame, count it in two halves with a chalk line between them.
5. Keep the whole bundle in the frame, with a margin all round. A bar cut off by the photo edge counts only when at least half of it shows; the rest are flagged for you to decide.
6. Even light. Low sun across a bundle throws shadows between the bars. Keep the sun behind you.

More detail, with the mistakes that cost the most bars: how to count pipes and rebar in a photo.

Checking a rebar delivery

The most common job: a truck arrives, and you need to know the bundle count matches the delivery note before you sign.

1. Photograph each bundle's ends as it comes off the truck.
2. Check the orange rings. Tap Check to step through the spots it was unsure about, and tap to add or remove a bar.
3. Compare the count with the bundle tag or the delivery note.
4. Save the image with the count drawn on it. If a bundle is short, you have a photo with every bar marked to send to the supplier.

Some yards check deliveries by weight. A photo count gives you pieces directly, and the length of the bars makes no difference to it.

How accurate is it on rebar?

The round-ends model scores 91% count accuracy before you check anything. Count accuracy is 100% minus the average counting error, measured in the browser on held-out photos with 10 or more objects that the models never trained on, before any checking. That figure comes from photos of pipe bundles. Rebar has no test set of its own yet, so treat the number as a guide for rebar, and use the Check step on every count you sign for.

The model rarely rings something that is not a bar end. Most of its misses are tiny, blurred ends deep in dense bundles, which is why getting close matters even more for rebar, with its smaller ends, than for pipe.

Other counters

Pipes, tube and conduit: count pipes from an image. Square tube and timber ends: the lumber counter. Logs: count logs in a photo. Couplers, spacers or bar chairs: count them by example with Anything. Using CountRods or CountThings today? See how the free counter compares.

On site every day? Count rebar from the iPhone camera

The web counter is free for every bundle. For daily counts, the Counting Master app for iPhone is quicker on site:

• Count from the camera. Rebar counts in the app's Round ends mode. The camera shows when the phone is level and warns about blur, glare and dark light before you count, and it works with no signal.
• Teach it your own items. If you count something the round-ends model handles poorly, count it by tapping one example and save it as an item. After 20 checked counts, your iPhone trains a counter for that item, and it counts by itself from then on.
• Keep a history of every delivery count on the phone.

iPhone, iOS 17 or later. The first three counts are free. Get Counting Master for iPhone