River Thames
The River Thames is a major river in southern England that flows through London and empties into the North Sea.
Also known as: Thames, Thames River
How big is it?
346 km · approximate main-channel length
Also 215 mi
Approximate main-channel length · approximate
Typical recorded range: 340 km to 350 km.
A little perspective
River Thames vs Mimas: length comparison
The mean diameter of mimas is about 1.15 times the main-channel length of the River Thames.
The River Thames is a major river in southern England that flows through London and empties into the North Sea.
Mimas is an icy moon of Saturn, visually dominated by the large Herschel impact crater.
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
Measurements, assumptions & sources +
River Thames
Approximate main-channel length: 346 km; approximate; range 340 km–350 km.
The River Thames is commonly quoted as approximately 346 km from source to the North Sea. Source choice, tidal reach and channel-centreline convention affect measured length.
Encyclopaedia Britannica — River Thames
The marked approximate main-channel length is calibrated. Unmeasured illustration details are representative.
Mimas
Mean diameter: 396.4 km; approximate; range 395 km–398 km.
Saturn’s moon Mimas is about 396 km across and dominated visually by Herschel crater. The diameter is a mean for an imperfect sphere.
NASA JPL — Planetary satellite physical parameters
The marked mean diameter is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
Change your perspective
Put it next to…
Choose a suggestion to redraw the comparison, or open its page to learn what it is.
Why this measurement?
Why we use 346 km
We compare the main-channel length of the River Thames. This is an estimate; check the notes for its rounding and uncertainty. The recorded range is 340 km to 350 km.
The River Thames is commonly quoted as approximately 346 km from source to the North Sea. Source choice, tidal reach and channel-centreline convention affect measured length.
The marked horizontal span follows the measured feature, not the edges of the image. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 346 km | 340 km to 350 km | approximate |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valuePlanets, moons and spaceHyperion270 kmMean-equivalent diameterHyperion is a porous, irregularly shaped moon of Saturn that rotates chaotically and has a sponge-like surface.
Around the same scalePlanets, moons and spaceMimas396.4 kmMean diameterMimas is an icy moon of Saturn, visually dominated by the large Herschel impact crater.Nearest higher valuePlaces and natural featuresGrand Canyon446 kmCanyon lengthThe Grand Canyon is a vast, steep-sided gorge carved by the Colorado River in northern Arizona, United States.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- Encyclopaedia Britannica — River ThamesApproximately 346 km from source to the North Sea under the cited river convention.
There’s always another scale
Follow your curiosity.
PlacesSeine777 kmThe Seine is a river in northern France that passes through Paris and flows into the English Channel.PlacesAmazon River6,400 kmThe Amazon River is a major waterway in South America that flows eastward across the continent and drains a vast rainforest basin.SpaceMimas396.4 kmMimas is an icy moon of Saturn, visually dominated by the large Herschel impact crater.TransportFive-hour drive at 100 km/h500 kmA five-hour drive at a set speed is the distance a vehicle covers in five hours of continuous travel without breaks.
SpaceEnceladus504.2 kmEnceladus is a natural satellite of Saturn, with an icy surface and plumes of water vapour erupting from its south pole.
Places10,000 km² region10,000 km²A region is a large expanse of land defined by geographical or administrative boundaries.TransportOne-hour drive at 100 km/h100 kmA one-hour drive at a set speed is the distance a vehicle travels in one hour of uninterrupted motion.
SpaceCharon1,212 kmCharon is a natural satellite of Pluto, composed mainly of rock and water ice.