Marchlyn via Mynydd Perfedd up Elidir Fawr: route map, distance and time
924 m · Snowdonia
Elidir Fawr is the western end of the Glyderau in Snowdonia, a large mountain above the Dinorwig quarries and the reservoir of Marchlyn Mawr.
A hard mountain walk to the summit from Marchlyn public road end (SH596631).
Marchlyn via Mynydd Perfedd starts at about 362 m and gains 629 m over 5.9 km to 888 m on the track. The first 2 km are the easy part, averaging 10%. The steepest kilometre is the one ending at 5.9 km, which climbs 169 m at an average of 19%, with a 500 m stretch from 5.1 km at about 25%. That last pull ends at the summit. About 16% of the way is steeper than 1 in 5, so expect hands-on-knees going and a slow descent.
Marchlyn via Mynydd Perfedd at a glance
| Distance | 5.9 km one way, to the top |
|---|---|
| Ascent | 670 m |
| Climb on the track | 629 m up, 106 m down on the way |
| Start and top of the track | 362 m to 888 m (summit 924 m) |
| Steepest 500 m | About 25%, from 5.1 km |
| Steeper than 1 in 5 | 16% of the way |
| Time up | 2h 20m by Naismith's rule |
| There and back | 3h 30m, down the same way |
| Grade | Hard |
| Start | Marchlyn public road end (SH596631) |
| Start grid reference | SH 596 630 |
| Summit grid reference | SH 611 612 |
| Parking | No checked car park for this start; find lawful parking nearby |
Marchlyn via Mynydd Perfedd map
The track from the start (green) to the summit (blue), with a marker at each kilometre.
Height profile and getting to the start
Near the start
From OpenStreetMap, within 2 km. Check opening times before you rely on them.
Download the Marchlyn via Mynydd Perfedd GPX
Ascent only: plan your way down. A planning track, not checked on the ground; it doesn't show safe scrambling moves. Track data © OpenStreetMap contributors (ODbL), heights from a terrain model.
Marchlyn via Mynydd Perfedd kilometre by kilometre
Height, climb and average gradient for each kilometre of the track, with a grid reference at the end of each one to check your position on the map.
| At | Height | Climb | Gradient | Grid ref |
|---|---|---|---|---|
| 1 km | 463 m | +101 m | 10% | SH 605 627 |
| 2 km | 560 m | +97 m | 10% | SH 612 624 |
| 3 km | 701 m | +140 m | 14% | SH 618 629 |
| 4 km | 783 m | +82 m | 8% | SH 622 623 |
| 5 km | 719 m | -63 m | -6% | SH 619 615 |
| 5.9 km | 888 m | +169 m | 19% | SH 611 613 |
How long Marchlyn via Mynydd Perfedd takes
| Pace | To the top | There and back |
|---|---|---|
| Brisk 6 km/h, 8 min per 100 m up | 1h 55m | 2h 50m |
| Steady (Naismith) 5 km/h, 10 min per 100 m up | 2h 20m | 3h 30m |
| Relaxed 4 km/h, 12 min per 100 m up | 2h 50m | 4h 15m |
Times leave out stops. Coming down the same way, the table counts the ascent once; steep descents on rough ground can be as slow as the climb.
- Today: sunrise 07:48, sunset 18:14. Start by 13:44 to be down before dark, allowing 3h 30m for the walk and an hour for stops.
- Tomorrow: sunrise 07:50, sunset 18:12. Start by 13:42 to be down before dark, allowing 3h 30m for the walk and an hour for stops.
Elidir Fawr summit weather for this route
-
Good Today Sunday 18 October
Overcast, up to 5°C at the summit, feeling as cold as -4°C, summit wind 24 mph gusting 30 mph, 21% chance of rain. Rated Good. Sunrise 07:48, sunset 18:14.
-
Marginal Tomorrow Monday 19 October
Moderate drizzle, up to 6°C at the summit, feeling as cold as -1°C, summit wind 39 mph gusting 49 mph, 73% chance of rain. Rated Marginal. Sunrise 07:50, sunset 18:12.
Best day of the next seven for Marchlyn via Mynydd Perfedd: Sunday 18 October, with summit gusts around 30 mph and a 21% chance of rain.
Cloud inversion tomorrow morning: 3% (Low), best around 05:00. 7-day inversion outlook.
Hour-by-hour Elidir Fawr forecast · 14-day forecast · Is it safe to climb Elidir Fawr?
Before you go, also check: MWIS Snowdonia forecast · Met Office mountain forecast.
What to take today
- An insulated jacket, hat and warm gloves: it feels like -4°C on top.
- A waterproof jacket. It can rain on the tops in any forecast.
- A windproof layer, and poles for balance in gusts to 30 mph.
- Microspikes for icy paths. In snow, an ice axe and crampons and the skills to use them.
- Map and compass, and the skills to use them. A phone is a backup, not a plan.
- A head torch, food, water, a charged phone and a small first aid kit.
About Elidir Fawr
Elidir Fawr is the western end of the Glyderau in Snowdonia, a large mountain above the Dinorwig quarries and the reservoir of Marchlyn Mawr. More about Elidir Fawr, with the live forecast.
On the lists: Furth, Hewitt, Nuttall, Marilyn.
Extend the walk: tops near the summit
- Mynydd Perfedd (813 m), 1.3 km north-east
- Carnedd y Filiast (821 m), 1.7 km north-east
- Foel-goch (831 m), 1.7 km east
- Carnedd y Filiast North Top (720 m), 2 km north
- Y Garn (947 m), 2.6 km south-east
Challenges that include Elidir Fawr
- Welsh 3000s · 15
- Welsh 100 Challenge · 100
- Snowdonia 900m Peaks · 16
- Welsh Skyline · 9
- Paddy Buckley Round · 47
- Furths · 34
- Hewitts · 523
- Nuttalls · 442
- Marilyns · 1,555
More walks from Marchlyn public road end
Routes in Peakify's guides that start within 500 m of this one, for another day from the same car park.
- Marchlyn via Elidir Fawr and Mynydd Perfedd up Y Garn
- Marchlyn mountain-road approach up Carnedd y Filiast
- Marchlyn mountain-road approach up Mynydd Perfedd
- Marchlyn mountain-road approach up Foel-goch
Other routes up Elidir Fawr
| Route | Distance | Ascent | Time up | Grade |
|---|---|---|---|---|
| Nant Peris via the Afon Dudodyn | 3.4 km one way | 810 m | 2h 0m | Moderate |
| Marchlyn via Elidir Fach | 3.5 km one way | 560 m | 1h 40m | Hard |
| Ogwen via Y Garn and Mynydd Perfedd | 6.6 km one way | 920 m | 2h 50m | Hard |
In an emergency
Call 999, ask for the police and then mountain rescue. Give your location (the start is at SH 596 630, the summit at SH 611 612), what happened and how many are in your group. If you have no signal for a call, a text to 999 works once you have registered your phone with emergencySMS: text "register" to 999 before you go.
Marchlyn via Mynydd Perfedd: questions and answers
How far is Marchlyn via Mynydd Perfedd?
Marchlyn via Mynydd Perfedd is 5.9 km one way to the summit of Elidir Fawr, with 670 m of ascent. There and back by the same way is about 11.8 km.
How long does Marchlyn via Mynydd Perfedd take?
About 2h 20m to the summit of Elidir Fawr and 3h 30m there and back by Naismith's rule (5 km/h plus 10 minutes per 100 m of ascent), before stops. A relaxed group takes nearer 4h 15m for the round trip.
How steep is Marchlyn via Mynydd Perfedd?
The steepest 500 m averages about 25%, starting 5.1 km from the start, and 16% of the way is steeper than 1 in 5. Marchlyn via Mynydd Perfedd climbs 629 m in all on the track.
Where do you park for Marchlyn via Mynydd Perfedd?
Marchlyn via Mynydd Perfedd starts from Marchlyn public road end (SH596631). The grid reference is SH 596 630. No checked car park for this start; find lawful parking nearby
Is Marchlyn via Mynydd Perfedd suitable for beginners?
Not as a first mountain. Peakify grades it Hard: steep, rough ground where a slip matters. Build up on an easier route first, such as Nant Peris via the Afon Dudodyn.
What time should I start Marchlyn via Mynydd Perfedd today?
By 13:44 at the latest. Sunset on Elidir Fawr today is 18:14, Marchlyn via Mynydd Perfedd takes about 3h 30m there and back, and that leaves an hour for stops. Start earlier in winter or if the forecast turns.
Is there a GPX for Marchlyn via Mynydd Perfedd?
Yes. Download it from this page. It is an ascent-only planning track from the start to the summit, plotted on OpenStreetMap paths and not checked on the ground.