Mars 4 Ultra vs Mars 5 Ultra: Which to Buy

Both the Elegoo Mars 4 Ultra and the Elegoo Mars 5 Ultra run 18 micron pixels. Both use the same small Mars build plate: 153 by 77 by 165 mm. Both sit in the budget tier of the current resin market. The decision is not about resolution or build volume. It is about whether the Mars 5 Ultra’s tilting VAT is worth $80 more than the Mars 4 Ultra’s straight peel, and what you give up on each side of that gap.

That is the entire article. Everything below is the detail you need to answer it for your own situation.

The two machines at a glance

The Mars 4 Ultra sits at around $170. For that money you get an 18 micron pixel screen, tempered glass over the LCD, ACF release film in the VAT, a built-in air filter, and anti aliasing support via the .cbt file format. It does not have a tilting VAT, auto levelling, or RERF in the menu. It does not print fast by the current generation’s standard, but it prints correctly.

The Mars 5 Ultra sits at around $249. For the extra $80 you gain the tilting VAT, auto levelling, and RERF support built into the menu. You lose the built-in air filter. The film is nFEP rather than ACF. The anti aliasing situation is less clear: the database lists the Mars 5 Ultra as “Unsure” on AA support, which matters if you are printing detailed character miniatures where smooth curved surfaces are painted.

The $80 gap is the frame for everything that follows. The spec sheets look nearly identical because the headline figure, 18 micron pixels, is the same on both machines. The actual day to day experience is different.

What the Mars 5 Ultra’s tilting VAT actually does

Elegoo solved the speed problem by tilting the VAT. That sentence matters more than it sounds.

When a resin printer finishes a layer, it has to lift the print off the film at the bottom of the VAT. On a straight peel machine the plate lifts straight up, peeling the cured layer away from the film in a single motion. That peel force is what causes fine details to tear. The capes, spear tips, and fingers on miniatures are thin enough that the peel pulls them away from the plate rather than letting them come with it.

A tilting VAT changes the geometry of that peel. Instead of pulling the whole layer straight up, the VAT tilts sideways and the release happens progressively from one edge. Peel force drops significantly. What that means in practice is that fine miniature features are less likely to tear on the lift, print speeds increase because the lift cycle is shorter, and the machine can print reliably at settings that would stress a straight peel printer.

Anycubic took a different approach to the speed problem on their M5S line. They chased faster prints by going to 100 micron layer heights, thinner FEP film, and brittle fast-flowing resin. The result was a noticeably worse print. Elegoo’s tilt-VAT approach keeps the 18 micron pixel size and does not ask you to change your resin to get the speed benefit. That distinction is the reason the Mars 5 Ultra is the stronger daily machine.

What you give up on the Mars 4 Ultra to get there

The Mars 4 Ultra has three things the Mars 5 Ultra does not, and one of them matters more than the others.

The built-in air filter is a real feature. Resin printing produces fumes, and a printer that scrubs those fumes internally without requiring a separate box or a window to be open is a meaningful quality of life improvement. The Mars 5 Ultra has no air filter. If you are printing in a small room or in a space shared with other people, this is the feature to weigh. It does not affect print quality but it does affect whether the printer is practical where you plan to use it.

The ACF release film on the Mars 4 Ultra is a smaller advantage but a real one. ACF film generates lower peel force than standard nFEP on a straight peel machine. The Mars 5 Ultra uses nFEP but offsets that with the tilt mechanism. In practice the Mars 5 Ultra’s tilting VAT more than compensates for the nFEP film. The ACF advantage on the Mars 4 Ultra is not nothing, but it is not a reason to prefer the older machine over the Mars 5 Ultra on tilt-VAT grounds.

The anti aliasing situation deserves its own paragraph. The Mars 4 Ultra can save files as .cbt format, which handles anti aliasing correctly. The standard .goo format from Elegoo’s slicer has issues with anti aliasing, and the Mars 4 Ultra’s .cbt support is what makes that workable. The Mars 5 Ultra’s AA support is listed as “Unsure” in the current machine database. For most print jobs this is not visible. For detailed character miniatures with smooth faces and armour curves, it can be. If anti aliasing is a priority for your work, the Mars 4 Ultra has the cleaner answer. If you use Chitubox or Lychee rather than the manufacturer slicer, the picture may differ, but the Mars 4 Ultra is the machine with the confirmed capability.

Tilt VAT longevity

This section exists because it is honest, not because it is a deal-breaker.

There are some reports of tilt VAT mechanisms failing over time. The mechanism adds moving parts to the VAT that a straight peel printer does not have. Moving parts wear. How often that actually happens, and over what printing lifetime, is not something the current data can say precisely. The phrase “some reports” is accurate and deliberately vague because inventing a failure rate would not serve you.

What it means practically is that the Mars 5 Ultra carries a known long-term uncertainty that the Mars 4 Ultra does not. For a new buyer printing at a typical hobbyist rate of two to three sessions a week, this is worth being aware of rather than worrying about. The tilt VAT is still a better daily mechanism for most print jobs. But if you are looking for the printer with the fewest moving parts and the longest expected service life, the Mars 4 Ultra’s straight peel is the simpler machine.

Build plate cleanup

The Mars 5 Ultra’s build plate pools quite a lot of liquid resin on top after a print. This is a minor annoyance at cleanup but it shows up every single print, not just occasionally. Resin sitting on top of the build plate has to be managed before it drips somewhere it should not, which adds a step to the post-print process.

This is not a reason to reject the machine, but it is the kind of thing that does not appear on a spec sheet and does appear in real use. The Mars 4 Ultra does not have the same issue to the same degree. Worth knowing if cleanup workflow matters to you.

Auto levelling and RERF

The Mars 5 Ultra has both. The Mars 4 Ultra has neither.

Auto levelling on the Mars 5 Ultra works. For a new printer owner who has never levelled a build plate before, it is genuinely reassuring. The plate self-levels at the start of a print and the machine confirms the result. For an experienced user who has levelled plates manually on previous printers, it is less transformative but still a convenience. It is not a reason to pick the Mars 5 Ultra on its own, but it is a real feature.

RERF in the menu is a more meaningful upgrade. RERF stands for Resin Exposure Range Finder and it is the fastest reliable way to dial in a new bottle of resin on a specific printer. When you open a new resin you do not know its ideal exposure time on your machine at your layer height. RERF prints a small test across a range of exposures and shows you exactly where the sweet spot is. The Mars 4 Ultra requires you to run this test through the slicer and set it up manually, which is doable. The Mars 5 Ultra has it in the printer menu, which is faster and more beginner-friendly. If you are someone who switches resins regularly or wants to dial in each bottle precisely, RERF in the menu is worth having. You can read the full approach in the guide to reading RERF exposure test results.

Who each machine is for

The Mars 4 Ultra is the right choice for the buyer who wants a small Mars format printer at the lowest sensible price, wants confirmed anti aliasing support for detailed character work, and values having the air filter built in. It is also the right choice if the printing space is small or shared and managing fumes without a separate external filter matters. It is a competent printer that prints in the same pixel-size league as the Mars 5 Ultra at $80 less.

The Mars 5 Ultra is the right choice for the buyer who prints regularly and will benefit from the tilt VAT speed gain across a lot of sessions, values the RERF convenience, and is not in a situation where the lack of an air filter is a problem. The tilting VAT shapes the daily printing experience more than any other feature difference between these two machines. If the $80 headroom is comfortable, the Mars 5 Ultra is the better daily printer for most new owners in 2026.

Neither answer is wrong. These are genuinely different machines despite the shared pixel size, and the right one depends on which set of trade-offs fits your situation. If you are still weighing the broader resin market and not committed to the Mars line specifically, the guide to choosing the right resin 3D printer covers the decision from the top.

The honest verdict

If $80 of budget headroom is comfortable, the Mars 5 Ultra is the better buy for most new owners. Speed and the tilting VAT define the daily printing experience in a way that the air filter and ACF film on the Mars 4 Ultra do not, and auto levelling and RERF in the menu are genuine conveniences for a beginner building their first printing habits.

If $80 is not comfortable, the Mars 4 Ultra is not a compromise. It prints at the same pixel size, has confirmed anti aliasing support, and costs less to run in a space with fume management concerns. The second hand value on the Mars 4 Ultra is strong, which makes it an even more interesting option if you are not committed to buying new.

Both machines are worth buying in 2026. Both are recommended picks. This article exists because the spec sheets look identical and the real differences are not on the spec sheet.

Where to look next

Both machines sit on the best resin 3D printer for miniatures buying guide alongside the full current recommended list. If you are also weighing the plain Mars 4 against the Mars 4 Ultra, that is a closer comparison than this one with a shorter price gap to justify. The 2026 overview of the resin printer market gives the full picture of why this generation represents better value than almost any previous one.