ESL gateways: how many you need and how to check

An ESL gateway is the radio access point that carries price changes from the store network to the labels. Vendors publish indoor ranges of 10 to 30 m and capacities of 1,000 to 2,500 labels per unit, but those are catalogue figures: the real number of gateways comes from a coverage survey in your store, with your fixtures in place.

This page covers only that calculation. What a gateway is within the system and which radio bands exist is in the technical guide to electronic shelf labels; we start from there and stay with one question: how many do you need, and how do you check before signing.

What vendors publish, and what they do not

The material is thin. Searching for citable data we found ranges for only a few products, and almost none came with the measurement conditions.

Source	Range	Capacity	Power
Opticon EBS-40	25 m typical indoors, 100 m open field	Up to 2,500 labels (with an EE-214 label and default settings)	4.5 to 6.6 V; two Ethernet ports; leaflet does not mention PoE
Dahua ESL-AP-A	20 m radius indoors	“2000+” labels per access point	48 V PoE; ceiling mount
Waveshare (development kit)	10 to 30 m indoors	Not stated	48 V PoE; dual-band Wi-Fi
MRB Retail (reseller article)	Not stated	“Typically” about 1,000, “but not absolute”	Not stated

Three readings of this table.

First, “indoors” is not “your store”. Opticon itself separates 25 m indoors from 100 m in open field, and that four-to-one gap shows what walls and fixtures cost. None of the vendors we read says how much a metal shelf full of product takes away.

Second, capacity comes with small print. Opticon’s 2,500 holds for one specific label and default settings; the same leaflet gives a 250 kbit/s transfer rate and more than 10,000 full image updates per hour with a 2-inch label. Capacity is an addressing ceiling. What matters day to day is how many labels change at once, how often, and how large the image is.

Third, and least comfortable: the Bluetooth ESL standard lets one access point address up to 32,640 labels, according to the Bluetooth SIG. That is a property of the protocol and says nothing about how many one radio serves well in a given store.

From radius to square metres, carefully

A 20 m radius draws a circle of about 1,260 m²; 25 m gives about 1,960 m²; Waveshare’s extremes (10 and 30 m) give 310 to 2,830 m². That is our arithmetic, not a vendor figure, and it describes an empty space with line of sight. It is good for one thing: seeing that a small shop fits under a single gateway at an ideal 20 or 25 m, while a 20,000 sq ft store cannot be solved by dividing by area.

The reason is that labels are not spread across the floor; they sit in aisles. The signal has to reach a shelf face, often the far side of a six-foot fixture that blocks it, at several heights. The MRB Retail article says it without numbers: the size of the coverage zone determines how many labels the station can serve, and label distribution matters. Concentrated labels mean less load; labels scattered over distinct zones mean more units.

What reduces coverage

We found no vendor that publishes attenuation by fixture type. What follows is what the sources support, and what they do not.

• Walls and obstacles. MRB Retail cites wall thickness and interference from other electronic devices as factors that change the usable label count. Opticon’s 25 versus 100 m points the same way.
• Other 2.4 GHz radios. Many systems share the band with Wi-Fi. Meraki’s guide for Vusion labels recommends, on Wi-Fi 5 Wave 2 access points, using 5 GHz for Wi-Fi and 2.4 GHz for labels. It also lists recommended label channels (3, 5, 8, 9 and 10) and notes that each label channel occupies 1 MHz, against 22 MHz for a 2.4 GHz Wi-Fi channel.
• Metal shelving, cold rooms, high ceilings. No published data. A metal shelf or a frozen-food cabinet can block the signal, but how much is only known by measuring. The same goes for ceiling height: the Dahua gateway is ceiling-mounted and the Opticon takes a DIN rail on a wall or ceiling, but no leaflet links height to range.
• Cold. Freezer labels have their own battery and refresh limits, covered in our article on labels for chilled and frozen food. For the gateway, what matters is its operating temperature range: Opticon lists -10 to 50 C and Dahua -10 to 60 C, so neither goes inside the cold cabinet; it sits outside, pointing toward it.

The coverage survey, step by step

The way to cut uncertainty is a small prior survey, not a desk calculation.

1. Ask for the plan with fixtures. A floor plan without furniture is of little use. Mark metal shelving, cold rooms, columns, false ceilings and clear height.
2. Ask for range with conditions. Get in writing what “20 m” means in that quote: indoors with fixtures or open space, at what height and with which label.
3. Test with one gateway and real labels. Mount it where planned, place labels in the worst spots (the back of a metal run, the end of an aisle, next to the cold room) and force several updates. It is what a pilot does, in miniature.
4. Measure the response, not only the change. A label that changes after several retries passes the test and burns extra battery. Look at how many attempts it needs and whether the platform shows signal quality. Meraki warns, for instance, that on natively integrated access points there is no Bluetooth signal heat map or automatic label channel planning: an Ekahau survey only shows how many access points hear each other.
5. Record the position. With the result, fix height, location and cable run for each gateway in the plan of the rollout.

Network and power

The sources say little, but enough to ask the right questions.

• PoE. Waveshare and Dahua list 48 V PoE. Neither page names the standard (802.3af, at or bt), so ask for the wattage. Opticon powers the EBS-40 with 4.5 to 6.6 V and 200 mA, and its leaflet does not discuss PoE. If the project counts on a PoE switch, that difference changes the cabling budget.
• One cable per gateway. Every model reviewed needs a connection to the store network. With high or false ceilings, cabling is a works line item and not just materials.
• Separate or shared network. Meraki documents that its natively supported access points act as label gateways, but that the label function is incompatible with other IoT radio functions such as Bluetooth. If you already run corporate Wi-Fi, check whether the same hardware works or whether you need a second network.
• Platform connection. Ask whether gateways talk to a local or a cloud server, and what happens to price changes if the internet uplink drops.

Redundancy

No document we read describes a redundancy mechanism between gateways. The closest is the case MRB Retail reports: a supermarket added a second access point to improve stability and response time. That is a reseller anecdote, not a specification.

So redundancy has to be requested in writing, with three questions:

• If a gateway goes down, does another cover its labels, or do they stay unupdated until repair?
• Do coverage zones overlap by design? A label that hears two gateways is more tolerant, but uses more of the channel plan.
• How does the platform report an outage? The sooner it is detected, the fewer labels keep a stale price. Also ask what the label displays while it receives no updates, because what matters legally is that the shelf price matches the till, as explained in till price different from shelf price.

How to ask for the quote

An honest gateway quote includes the number of units, the position and height of each, the range assumption with its conditions, the power supply, the list of cables to run and a commitment to adjust if the survey or pilot contradicts the plan. If it only gives a gateway count divided by floor area, it is untested.

The cost of gateways and cabling belongs in the total project cost. To line it up with the rest, use the total cost calculator.

Limits of this page

The figures come from vendors and one reseller, read on 9 November 2026, and we could not check them in a real store. We give no “one gateway per so many square metres” rule because no source supports one. Nor did we find published attenuation data for metal shelving, freezers or ceiling height; if a supplier gives you any, ask for the measurement condition.