GPS for Farming in the UK: Guidance, Autosteer and RTK Explained
Three accuracy tiers, three price tags, and a short list of jobs that actually need centimetres. Every figure sourced. Last updated 3 September 2026.
Three Tiers of Farm GPS
| Tier | Correction signal | Accuracy | Running cost | Good for |
|---|---|---|---|---|
| Free | EGNOS, the European satellite-based correction, picked up by any SBAS-capable receiver | Within 1.5 m absolute (ESA); an entry light bar is specified at 20 cm pass-to-pass or better | £0 | Spraying and spreading on existing tramlines, field measurement, guidance you do not have to come back to |
| Paid satellite | Manufacturer correction beamed from satellite — no mobile signal needed | 2.5–3 cm claimed (Trimble CenterPoint RTX, John Deere SF3) | About £650 a year (RTX, 2024 dealer price) | Farms with poor mobile coverage that want near-RTK repeatability |
| RTK | Corrections from a base station, delivered over mobile data (NTRIP) or your own base and radio | Centimetre level; a farm base is quoted at 10 mm pass-to-pass in suitable conditions | £375 + VAT per tractor per year base-free, or £2,995 + VAT for a farm base then £199 + VAT a year | Drilling, bed forming, hoeing, controlled traffic, strip-till — anything that must return to the same line |
The mistake the brochures encourage is buying the top row for a job the bottom row does. Most of the money in farm GPS is in the correction subscription and the steering hardware, not the receiver, so the question to answer first is which of your jobs need to come back to exactly the same line next year.
Two Different Accuracies, And Why Both Matter
Absolute accuracy
How close the receiver's position is to where you truly are on the map. This is the figure ESA publishes for EGNOS — within 1.5 metres — and it is why the free signal cannot return to last year's drill rows: a metre and a half of wander between seasons is a row out. RTK fixes this by measuring against a base station whose position is known to the centimetre, which is why UK RTK providers calibrate their bases against Ordnance Survey's OS Net.
Pass-to-pass accuracy
How well the receiver repeats a line it drove a few minutes ago. Errors that drift slowly cancel out over a short interval, so pass-to-pass is always tighter than absolute. DEFRA's FETF specification for a grant-eligible light bar asks for 20 cm pass-to-pass or better, and that is the accuracy that matters for a spraying or spreading bout: the next bout, not next year. When a seller quotes one number, ask which of the two it is.
Three Ways To Get Centimetres in the UK
RTK is the same maths whoever sells it; what differs is where the base station is and how the correction reaches the tractor.
Network RTK over mobile data (NTRIP)
A subscription to someone else's network of bases. The correction arrives over a mobile data SIM, so it needs signal in the field. Published UK prices: £375 + VAT per tractor per year base-free (RTK Solutions, 2026), and Farmers Weekly listed £450 to £650 a year including the SIM from other suppliers in 2024. NTRIP is brand-neutral: almost any RTK-capable receiver can take corrections from any provider, which is what lets you shop the price. The larger networks — SmartNet, VRS Now, Topnet Live, FarmRTK, EssentialsNet — are built on OS Net stations.
Your own base station
A base on a shed roof, corrections by radio or over the farm's internet. One farm-oriented package: £2,995 + VAT including the hardware and year one, then £199 + VAT a year for network access, covering every compatible machine on the farm from one installation and quoted at up to 10 mm pass-to-pass with a typical 35 km range. Radio-only bases from mainstream brands ran £10,000 and up in 2024, and radio range is about 12 miles. Pays when there are several tractors or a subscription per machine would add up.
Satellite-delivered correction
The manufacturer computes the correction and beams it down from a satellite, so no mobile signal is needed. Trimble CenterPoint RTX claims 2.5 cm and John Deere SF3 3 cm pass-to-pass; a UK dealer quoted RTX at £650 a year in 2024. Not RTK strictly, but close enough for most jobs that need it, and the only realistic option where the phone does not work in the bottom field.
Light Bar, Assisted Steer or Autosteer
Three rungs of hardware, and the government has published what it expects each to cost.
| Rung | What it is | Expected cost | Source of the figure |
|---|---|---|---|
| GPS light bar | A display that shows the driver the line; the driver steers. FETF's spec: 20 cm pass-to-pass or better, linked to a phone or tablet, straight and curved guidance, field boundary measurement | £809 | FETF 2026 item FETF46 (grant was £323) |
| Assisted steer, retrofitted | An electric motor on or replacing the steering wheel, driven by an existing GPS. Software unlocks for factory systems do not count | £1,911 | FETF 2026 item FETF47 (grant was £764) |
| Complete RTK autosteer retrofit | Touchscreen, RTK-capable receiver, steering-wheel motor, wheel-angle sensor | £2,950–£5,994 | UK dealer kits, August 2026; AHDB's basic-system figure is ~£4,500 |
Two things the table hides. The FETF figures are expected costs, not the cheapest kit that meets the spec — and its rule that a light bar and an assisted-steer system had to be bought and invoiced as separate items tells you those are the two decisions, not one. And the receiver in the autosteer kit is only RTK-capable: the correction subscription in the section above is on top, every year. The payback arithmetic — AHDB's break-even at roughly 75 hectares of cereals for a basic system — is on our costs page.
Which Jobs Need Which Accuracy
The free tier usually does it
- Spraying and spreading on existing tramlines — the tramline holds the line; the light bar is there for the headland and for the width you cannot see.
- Measuring a field, mapping a boundary, marking where you stopped — 1.5 m absolute is fine for a hectare figure.
- First-time guidance on a tractor that never had any — the overlap saving on a 24 m sprayer does not need centimetres.
Centimetres, or do not bother
- Drilling into or between last year's rows, strip-till, precision planting — season-to-season repeatability is the whole point, and only RTK has it.
- Bed forming, inter-row hoeing, mechanical weeding — the tool works within a few centimetres of the crop. SFI26 pays £150/ha/year for robotic mechanical weeding, which is a guidance job before it is a robot job.
- Controlled traffic farming — every wheel on the same track every year; DEFRA's survey found 8% of eligible farms doing it.
Variable-rate spreading and camera-guided spraying — the SFI26 actions that pay £27 and £43 per hectare per year — sit in the middle: the rate map needs to know where the machine is to a few metres, not centimetres, so the free tier serves them. What they need is section control on the machine and a map worth following, which is where our free field NDVI viewer and RB209 nutrient calculator come in.
What the Grants Say About GPS
FETF — paid for the kit, closed for 2026
The 2026 list carried both entry rungs: FETF46 GPS light bar, £323 grant on an £809 expected cost, and FETF47 assisted steer, £764 on £1,911, plus FETF50, a retrofitted variable-rate and section controller at £1,945. The round closed on 12 May 2026 and DEFRA has said it was the last standalone one; a consolidated offer is planned from 2027. The item specifications are still the clearest published definition of what counts as fundable guidance kit, so they are worth reading before the 2027 offer appears. The full FETF list.
SFI26 — pays for the practice, not the receiver
No SFI26 action buys GPS. Three pay per hectare for things that need it: PRF1 variable rate application of nutrients at £27/ha/year, PRF2 camera or remote sensor guided herbicide spraying at £43, and PRF4 mechanical robotic weeding at £150. Window 2 is expected to open from 22 September 2026. Every action and what it pays; the whole funding picture is on the grants page.
What We Cannot Tell You
How many UK farms use GPS guidance. DEFRA's Farm Practices Survey, the official technique-by-technique measurement, counts soil mapping, variable rate, yield mapping and controlled traffic — it does not ask about GPS guidance or autosteer as a line of its own. Anyone quoting a national adoption percentage for tractor GPS is not quoting DEFRA. Our statistics page has the figures that do exist.
What the free signal repeats to, in your field. Pass-to-pass on EGNOS depends on the receiver, the antenna, the sky view and how long the bout takes. The 20 cm figure above is a specification a grant-funded light bar had to meet, not a measurement on your tractor. The reliable method is the one we recommend on every page: try the free tier on one machine for one season and measure the overlap, before paying for a subscription the job may not need.
Frequently Asked Questions
How accurate is free GPS on a tractor?
ESA puts EGNOS at within 1.5 metres absolute. Pass-to-pass is tighter: DEFRA's light-bar specification asks for 20 cm or better. Fine for a spraying bout, not for finding last year's rows.
What does RTK cost per year?
Base-free network RTK over mobile data: £375 + VAT per tractor per year from one UK supplier in 2026; £450 to £650 a year including SIM from others in 2024. Own base: about £3,000 + VAT once, then £199 + VAT a year.
Does RTK need a mobile signal?
Network RTK over NTRIP does. An own base with a radio link, or a satellite-delivered correction such as RTX or SF3, does not — that is the reason to pick either where coverage is poor.
Which jobs actually need RTK?
Anything that must return to the same line: drilling into old rows, bed forming, hoeing, controlled traffic, strip-till. Spraying and spreading on existing tramlines usually do not.
What does a guidance kit cost?
DEFRA's expected costs: £809 for a light bar, £1,911 for retrofitted assisted steer. A complete RTK autosteer retrofit was £2,950 to £5,994 from UK dealers in August 2026, before any correction subscription.
Is there a grant for farm GPS right now?
No. FETF 2026 funded light bars and assisted steer but closed on 12 May 2026; the 2027 consolidated offer has no published detail yet. SFI26 pays per hectare for practices that use guidance, not for the kit.
Every Figure on This Page
- ESA — What is EGNOS? (position “to within 1.5 metres”; positioning data “freely available in Europe”).
- GOV.UK — FETF 2026 productivity items and specifications (FETF46 light bar: 20 cm pass-to-pass spec, £809 expected cost, £323 grant; FETF47 assisted steer: £1,911 / £764; FETF50 variable-rate controller: £1,945 grant; the separate-invoice rule). Mirrored weekly into our FETF page.
- Ordnance Survey — OS Net (the GB base-station network; commercial RTK partners SmartNet, VRS Now, Topnet Live, FarmRTK, EssentialsNet and others).
- RTK Solutions — RTK subscriptions UK (£375 + VAT per tractor per year base-free; farm base £2,995 + VAT including year one, £199 + VAT a year from year two; 10 mm pass-to-pass, 35 km range). Market reference point, not an endorsement.
- Farmers Weekly — How to get cheaper or more accurate RTK guidance (2 February 2024) (NTRIP £450–£650 a year including SIM; CenterPoint RTX £650 a year, 2.5 cm; SF3 3 cm; radio range ~12 miles; own base £10,000+; brand-neutral NTRIP).
- AHDB — Precision farming of cereal crops (~£4,500 basic system, break-even above ~75 ha). Dealer kit prices £2,950–£5,994 as checked for our costs page, 16 August 2026.
- GOV.UK — SFI26 actions (PRF1 £27, PRF2 £43, PRF4 £150 per hectare per year).
- DEFRA — Farm Practices Survey, October 2019 (the techniques it measures; 8% controlled traffic farming; no GPS guidance line).
This page is educational, not advice. Prices are the published figures of the suppliers named, on the dates given, and change; check before relying on any of them.