The SaviMade egg compendium: 4 turtle eggs, drawn at true relative size, with the measurements behind our 3D-printable eggs, the colours behind our egg posters, and where every number came from.
3D print any turtle egg. Every egg in the compendium can be made into a 3D-printable model (an STL file) in our Egg Generator: pick the animal, check the size, and download a file ready for your slicer, for an FDM or resin printer. Use it for a nature table, a classroom, a museum display, decoy or replacement eggs for a collection, painting practice, or a set of eggs printed at true relative size. Each egg below has a Make a 3D-printable copy link that opens it there.
What this page is for. We built the compendium to show our sources. For each egg it lists where the length and width used for our 3D-printable models came from, and where the colour and markings used for our illustrated egg posters came from, so you can check them yourself.
Can’t find your egg? The collection doesn’t have every turtle in the world yet. If you know your egg’s length and width, you can make it yourself in the Egg Generator: type in the measurements, adjust the shape until it matches, and download your own 3D-printable egg.
About this collection. 4 turtle eggs so far; we are adding more. Sizes come from published measurements wherever we found them; shapes and colours are our best estimates (how accurate these eggs are).
Turtle egg families
How accurate are these eggs?
We work hard to get these eggs right, but we can’t guarantee that any of them are accurate. Real eggs vary, even within one nest, and published figures vary between sources. How sure we are depends on the number:
- Length and width: fairly confident. These come from published averages of measured eggs, and the source is given for every egg. Where no published average could be found (only a range or a rounded figure), the size is marked approx.; where no measurements at all could be found, it is estimated from related species and marked estimated.
- Diameter location and end roundness: less confident. These two numbers set the egg’s taper (where its widest point sits and how pointed the ends are). Sources rarely give them, so they’re estimated from the typical egg shape of the animal’s group (how the eggs are drawn).
- Colours and markings: least confident. The illustrations follow written descriptions and, where we could find them, photos of real eggs. Each one shows a typical egg; the real eggs of many turtles range widely in colour and pattern.
- Speculative eggs. For some species we haven't found a documented description or measurements of the egg yet. Usually the information exists somewhere and we just haven't found it; a few eggs are reported as undescribed in the sources we checked, and we say so. Rather than leave these eggs out, we estimate them from their closest relatives and label them Speculative. Treat them as a best guess: the estimates are updated as related species' eggs are measured, and replaced as soon as we find a real source.
If you spot a mistake or have a better source, please let us know.
Using these illustrations
Use these egg illustrations any way you like, including in your own work and things you sell, as long as you clearly credit Savi Made wherever they are displayed, sold or used publicly. Print them, share them, put them on posters, cards or products, or use them in teaching and articles.
A credit like this is all we ask, shown with the picture: Egg illustration by Savi Made (savimade.ca). Online, please link it to savimade.ca. You can also read how the eggs are drawn or make a poster of any eggs you like.
How these eggs are drawn
Every egg here is drawn from four numbers. Two are measured: its length and its width, taken from published averages of real eggs, with the source given for each egg. The other two set the egg’s taper: how much wider one end is than the other, and how pointed the narrow end is. Published sources rarely give those, so they’re estimated from the typical shape of eggs in the animal’s group (most turtles’ eggs are the same at both ends) and applied across that group. The same four numbers make the 3D-printable eggs and the poster outlines, so they all match.
The colours and markings in the illustrations follow each egg’s published description. Real eggs vary a lot, even within one nest; each illustration shows a typical egg.
The egg-shape formula
Every egg outline here comes from the egg-shape formula published by F. W. Preston in 1953, which he called the “standard avian egg-shape”. It is still regarded as one of the most accurate descriptions of the shape of birds’ eggs (Biggins et al. 2022). It uses four numbers:
- Length (L): the egg from end to end, in mm.
- Width (B): the egg across its widest part, in mm.
- End roundness (D): how blunt or pointed the two ends are. Half the length gives a plain oval; a smaller number makes both ends more pointed, and a larger one makes them blunter, up to a capsule shape at the full length.
- Diameter location (n): how much bigger one end is than the other. At 0 both ends are the same; higher numbers move the widest part towards the blunt end and taper the other end more. Most bird eggs are between about 0.5 and 3.
The outline is the egg’s radius r (half its width) at each point along its length:
r(t) = s · B⁄2 · √1 − t² · (1 + c1 t + c2 t²)
- t is the position along the egg, from −1 at the pointed end to +1 at the blunt end (t = 2x / L, where x is the distance from the middle in mm).
- c1 = n / 10 is Preston’s asymmetry term: it makes one end bigger than the other.
- c2 = D / L − ½ is his “biconical” term: it blunts or sharpens both ends equally.
- s scales the outline so that the widest part is exactly B.
With c1 and c2 both 0 the formula is a plain ellipse. The 3D egg is this outline spun around the egg’s long axis, and its volume is V = π∫r² dx, added up along the length.
Preston, F. W. (1953). The shapes of birds’ eggs. The Auk 70: 160–182.
Biggins, J. D., Montgomerie, R., Thompson, J. E. & Birkhead, T. R. (2022). Preston’s universal formula for avian egg shape. Ornithology 139(4): ukac028.