Best GPS Watch Under $300 for Marathon Training
A $300 cap can buy a useful marathon-training watch, but not every model has the same satellite mode, display, music variant or current price. This is a comparison of manufacturer documentation, not a hands-on accuracy test.
Each pick below is a conditional buying role (what it suits you for), not a measured ranking. Prices are US dollars; shipping, tax, variant and regional offers can push a watch above your cap.
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Compare the exact model
| Model | Display / positioning | Battery basis | Price basis |
|---|---|---|---|
| Garmin Forerunner 170 | 1.2â AMOLED; GPS / All Systems modes (no multi-band mode listed) | Up to 20h GPS-only / 14h All Systems; 10 days smartwatch | $299.99 US suggested retail price (Music: $349.99), Garmin, May 2026 |
| Garmin Forerunner 165 | AMOLED; GPS/All Systems, not a documented dual-frequency mode | Up to 19h GPS-only / 17h All Systems | $249.99 US launch price (Music $299.99); older model, check the current price |
| COROS PACE 3 | Transflective touchscreen; optional dual-frequency GNSS | Up to 38h standard GPS, not dual-frequency allowance | COROS price-adjustment notice lists US $199 |
| COROS PACE 4 | AMOLED; selectable positioning | Up to 41h All Systems (High), vendor claim | $249 US launch price and list price; variants cost more |
| Polar Pacer Pro | MIP; multi-satellite reception, not dual-frequency | Up to 35h GPS plus wrist HR | We could not confirm a current US price; check it before buying |
| Amazfit T-Rex 3 | AMOLED; dual-band GNSS, offline maps | Up to 42h Accuracy Mode, vendor claim | US page observed $279.99 |
Battery modes are not directly comparable. Music, display, sensors and navigation change runtime; these are manufacturer maxima, not measured marathon results.
Garmin Forerunner 170: the current Garmin entry point
The Forerunner 170 is Garminâs current-generation entry-to-mid running watch and, at $299.99, sits just inside the cap. Garmin describes a 1.2-inch AMOLED display, a touchscreen with five physical buttons, and premium running and training features brought down from its more advanced Forerunners. Garminâs ownerâs manual rates it at up to 20 hours in GPS-only mode and 14 hours in All Systems mode, with up to 10 days in smartwatch mode. Its battery table lists no multi-band mode. The Music model ($349.99) is above the cap.
Choose it when Garminâs workflow and a current-generation display matter and the extra $50 over the Pace 4 is worth it to you. See Forerunner 165 vs 170 and Forerunner 170 vs 265.
Garmin Forerunner 165: AMOLED and Garmin workflow
The manufacturerâs specification documents AMOLED, 39g and daily suggested workouts. Satellite settings distinguish GPS-only and All Systems; multiple constellations do not mean dual-frequency.
Music storage requires the Music variant. Garminâs launch pricing is the historical US launch price, not a guarantee of current stock. Its training features differ from the Forerunner 170 and 265, so check the feature list for the exact variant.
Choose it when Garminâs workout and app workflow and an AMOLED screen suit you; confirm the exact variant and price, and compare it with the newer Forerunner 170.
COROS PACE 3: running-focused budget role
PACE 3 specifications identify the transflective display, dual-frequency option, breadcrumb navigation and local audio support. The PACE 3 uses a transflective display, not AMOLED. The official price adjustment lists US $199 and different EUR/GBP/CAD amounts; current checkout still controls.
It remains a running-first budget option when its workout controls and display suit you. We make no accuracy claim beyond COROSâs own specifications.
COROS PACE 4: the lowest list price on this page
COROSâs release introduced the Pace 4 at a US price of $249, and COROSâs US store still lists it at $249. The current product page advertises AMOLED, maps and up to 41 hours in All Systems (High). Check installed firmware and regional product specification before relying on mapping features.
The 41-hour figure is COROSâs own rating for that mode, not an independent battery test.
Polar Pacer Pro: training workflow
Manufacturer specifications give up to 35 hours GPS plus wrist HR. The product page describes structured targets and wrist-based running power. We could not confirm todayâs US purchase price, so check that the offer you find is actually under $300.
Multi-satellite reception is not the same as dual-frequency GPS. Its role here is training functions and controls, not an unmeasured battery claim.
Amazfit T-Rex 3: rugged alternative, not $180 ultra-budget pick
The US listing, checked October 1, shows $279.99, dual-band positioning, offline maps and 42-hour Accuracy Mode. It is not an ultra-budget pick: the US listing shows $279.99. Fit, size, workout export and controls need evaluation for your running workflow.
Evaluate the current Amazfit lineup for a running watch within your budget
This approved evergreen lineup link does not promise a specific model is in stock or below $300 after tax.
Choose for your training
Keep COROS PACE 3 as the original budget running-workflow candidate; compare Garmin if you prefer that ecosystem, PACE 4 for current AMOLED/mapping features, Polar for its training workflow, and T-Rex 3 for its rugged role. No precision ranking is supported without a matched route test.
Check readability, recording controls, structured sessions and phone and strap compatibility before committing, and leave battery margin for the mode you choose. We do not claim a specific GPS accuracy percentage or that wrist heart rate suits every kind of training.
See all running-watch choices, Garmin/COROS/Apple comparison, Garmin/COROS comparison, budget shoes and our research methodology.
Garmin specifications and prices checked October 28, 2026; other brands as of October 1, 2026 unless stated. No first-hand testing and no lasting price guarantee.