Geofencing is a location-based marketing technique that draws a virtual perimeter around a physical location using GPS, Wi-Fi, cellular, or Bluetooth signals. When a device enters or leaves the zone, the system fires a pre-configured action — a mobile ad, a push notification, or an analytics event.
If proximity is the strongest signal of purchase intent for a local business, geofencing is how you buy attention at exactly that moment — the person walking past your door, or standing in a competitor's aisle.
What is geofencing?
Geofencing is a location-based advertising and analytics technique. Marketers define a virtual boundary — usually a circle or polygon on a map — and configure a trigger that fires when a mobile device carrying the platform's SDK enters, dwells inside, or exits the zone. The trigger is most often an ad impression, but it can also be a push notification, an analytics event, or a coupon offer.
The technique sits at the intersection of programmatic advertising, mobile app engagement, and offline attribution. It is most common among local retailers, restaurants, healthcare providers, auto dealers, and B2B marketers targeting trade shows.
Geofencing emerged with the iPhone SDK around 2010 and matured on programmatic platforms like The Trade Desk, StackAdapt, and Simpli.fi between 2016 and 2020. iOS 14's ATT (App Tracking Transparency) tightened consent requirements but did not kill the tactic.
Why geofencing matters
The value proposition is simple: relevance times timing. Four reasons marketers keep the tactic in the mix:
- Hyper-relevant reach. Ads are served when the user is physically near your business or a competitor — not when they idly scroll from a home in another state.
- Competitor conquesting. Fences around competitor addresses let you offer better terms to a device that just walked into their showroom.
- Event marketing. Trade shows, sports arenas, and concerts become one-day audiences. B2B and B2C both benefit.
- Offline attribution. Foot-traffic measurement matches ad exposure to store visits, giving digital campaigns a measurable offline outcome.
How geofencing actually works
Every geofencing platform follows the same three steps: define the zone, detect the entry, deliver the trigger.
shape: circle (or polygon)
center: 40.7128, -74.0060 # lat, lng
radius: 1500 ft
# 2. Detect device entry
signal: GPS / Wi-Fi / Cellular / Bluetooth
consent: explicit opt-in
# 3. Fire the trigger
action: serve programmatic ad
creative: 300x250 | landing page: /lp/lunch-deal/
Retargeting from a fence
The bigger payoff is geo-retargeting. Everyone who crossed the fence gets bucketed into an audience, then re-served ads across the open web and social for the next 15-30 days. This is where the ROI compounds beyond the in-zone impression.
Types of geofencing
| Type | Signal | Accuracy | Best for |
|---|---|---|---|
| GPS fencing | Satellite | 10-30 ft | Outdoor, most retail use cases |
| Wi-Fi fencing | Router MAC | 3-10 ft (indoor) | Malls, event floors, campuses |
| Bluetooth beacons | BLE beacons | 3-10 ft (indoor) | Aisle-level in-store targeting |
| Cellular fencing | Cell tower | 100-1000 ft | Rural areas, low-density fallback |
| IP fencing | IP address | City / postcode | Desktop reach, B2B office targeting |
Real geofencing examples
1. Neighborhood pizza — 1-mile fence at lunch
A single-location pizzeria drew a 1-mile fence around the store and served mobile display ads with a lunch-deal promo weekdays 11am-1pm. Foot traffic rose 22% within six weeks, measured via a redemption code.
fence: 1 mile radius around store
schedule: Mon-Fri 11:00-13:00
creative: $9 lunch combo
landing: /lunch-deal/?src=geo
2. B2B trade show conquest
A SaaS company fenced the convention centre during a three-day industry conference. Cost-per-lead came in 60% lower than the same brand's baseline LinkedIn campaign because targeting was pre-qualified by the venue.
3. Competitor conquesting for auto
A dealer fenced three competitor showrooms in a 20-mile radius. Anyone who visited a competitor got a "we beat any written offer" retargeted for 14 days.
Geofencing vs geotargeting — which one
They sound similar but sit at different scopes. One triggers on a boundary. The other filters on any location signal.
Use geofencing when
- You need block-level or venue-level precision
- You want to trigger on entry, dwell, or exit
- You need offline foot-traffic attribution
- You're targeting event attendees or competitors
- Radius is measured in feet or a mile
Use geotargeting when
- City, region, or postcode is precise enough
- You want cheaper reach at higher scale
- You're localising content, not triggering
- Local SEO landing pages are your goal
- Radius is measured in miles or kilometres
7 best practices for geofencing
- Match fence size to intent. A fine-dining restaurant might use a 5-block fence; a car dealership a 20-mile competitor conquest fence.
- Layer geo-retargeting. The in-zone impression is a rounding error. The 15-30 day retargeting window is where ROAS lives.
- Set dayparting. Lunch, dinner, and event windows convert 3-5x better than 24/7 blasts.
- Use polygon fences for real venues. A circle over a mall wastes budget on the parking lot next door. Draw the actual footprint.
- Rotate creative every 7-10 days. Location targeting shrinks the audience — fatigue kicks in faster than broadcast.
- Measure foot traffic, not just clicks. Programmatic geo platforms bundle offline visit attribution — use it.
- Get consent right. One privacy complaint is more expensive than a full campaign. Explicit opt-ins, opt-outs, clear disclosure.
You paid $3 CPM to serve an ad to someone who is already inside your store. Fence the approach, not the interior. And exclude staff phones from the audience.
Worked example: sizing and costing a geofence
Fence size is the decision that quietly sets your budget. Area grows with the square of the radius: a half-mile fence covers π × 0.5² = 0.79 square miles, while a two-mile fence covers π × 2² = 12.6 square miles. Four times the radius, sixteen times the area, and roughly sixteen times the population you are paying to reach.
Cost it out with hypothetical numbers. At a $9 CPM and 60,000 monthly impressions delivered inside the fence, spend is 60,000 ÷ 1,000 × $9 = $540 a month. A 0.4% click-through rate on those impressions is 240 clicks. If 3% of those clicks become booked jobs, that is roughly seven jobs, and at a $420 average ticket the campaign returns about $2,940 against $540 of media.
Change one input and the case collapses. Drop the click-to-job rate to 1% and you get two jobs and $840 in revenue, which barely clears the spend once you count the time spent managing it. Widen the fence to two miles at the same CPM and impressions climb while relevance falls, so cost per booked job rises even though the reported reach looks better.
The takeaway is to fence the drive-time area customers actually come from, then judge the campaign on cost per booked job rather than impressions or clicks.
Common geofencing mistakes
- Fence too large — a 10-mile radius on a coffee shop is just city-level geotargeting at premium CPM.
- No retargeting layer — in-zone impression only, no follow-up, low ROI.
- Ignoring consent — one CCPA or GDPR complaint can dwarf the campaign's total ad spend.
- Circle over a polygon shape — wastes 30-50% of the budget on adjacent buildings.
- Same creative for 30 days — small audiences see it too many times and tune out.
How theStacc helps with geofencing
theStacc's Local SEO module tracks whether your geofenced ads translate into store visits and Google Business Profile actions. We tie CPM-level ad exposure to direction requests, calls, and website clicks on the profile — so the geofence campaign has a measurable local outcome, not just an impression report.
Frequently asked questions
Match it to the drive time customers already accept, not to the map. For most service businesses that is a 10 to 15 minute drive, which is often one to three miles in a city and considerably more in a rural area. Because area scales with the square of the radius, every extra mile adds far more paid reach than it looks like it should.
No. Geofenced ads are paid placements and do not feed the local algorithm. Local Pack position comes from relevance, distance, and prominence signals such as reviews, categories, and citations. Geofencing can put your brand in front of people near you today, but the organic ranking work is separate.
GPS-based geofencing is accurate to 10-30 feet outdoors. Wi-Fi and Bluetooth beacons achieve 3-10 feet accuracy indoors. Cellular-only fences drift to 100+ feet.
Typical CPMs run $5-15 with minimum monthly budgets of $1,000-3,000 on programmatic platforms. Smaller Google Ads radius targeting starts far lower but is less precise.
Geofencing triggers an action when a device enters a small virtual perimeter. Geotargeting delivers content or ads based on any location signal, including broad city or postcode-level targeting.
Yes, when you obtain explicit location-tracking consent, disclose the purpose, allow opt-out, and only retain data as long as necessary. Buying anonymised device IDs from a compliant DSP is the usual path.
Yes. Conquesting fences around competitor locations are a standard tactic on programmatic platforms. Meta and Google restrict some competitive targeting, so third-party DSPs are typically used.
Related glossary terms
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