Is a Diplodocus really longer than a tennis court?
A Diplodocus measures 25 m (82 ft) end to end, and a tennis court measures 23.8 m (78 ft) end to end. That puts a Diplodocus at 1.05 times the length of a tennis court: 1.23 m (4.04 ft) of difference, 5%. Put the other way round, a tennis court covers 95% of a Diplodocus on the axis both are judged on. A Diplodocus and a tennis court are both written in tens of metres, and the 5% between them is the whole of the difference.
| Object | Real size | Axis measured | What the figure covers |
|---|---|---|---|
| Diplodocus | 25 m 82 ft |
Length | Average Adult |
| Tennis Court | 23.8 m 78 ft |
Length | Whole body or structure, end to end |
Both figures, Diplodocus and Tennis Court, come from the Size It Up measurement set, one real-world size and one measured axis per object, last checked in September 2026; outline provenance is listed on the sources page.
Why this one is hard to judge by eye
A Diplodocus sits in the range with no handy yardstick: too big to hold against anything you have carried, too small to need a horizon, so it and a tennis court end up filed under the same vague heading of very large. A gap of 5% is invisible without a shared baseline: on the ground line above, a tennis court stops 1.23 m (4.04 ft) short of a Diplodocus.
What each figure covers
Diplodocus. Diplodocus is quoted nose to tail tip, and the tail is close to half of it. Vertebra counts differ between specimens, so published lengths move by several metres.
Tennis Court. A tennis court is measured baseline to baseline. The doubles width is wider than the singles width, but the length never changes.
A Diplodocus and a tennis court are both quoted as a length, which is what makes the ratio above a like-for-like figure.
What else is about that size?
Measured the same way, Diplodocus at 25 m sits within a quarter of Blue Whale at 27 m, James Webb Space Telescope at 21.2 m and Cricket Pitch at 20.1 m. Tennis Court at 23.8 m has James Webb Space Telescope at 21.2 m, Blue Whale at 27 m and Cricket Pitch at 20.1 m for company, within a quarter. Swapping any of those in for a Diplodocus would move its ratio to a tennis court by less than 25%.