Buy the Formlabs Form 4 when resin printing is recurring professional work and faster output, current workflow features, and lower operator friction can repay the upgrade. Buy a Form 3+ only when a verified used or legacy-system discount remains compelling after you price condition, tanks, cartridges, post-processing, service coverage, failed-job risk, and operator time.
This is not simply “old printer versus new printer.” Formlabs lists a 20.0 × 12.5 × 21.0 cm build volume for Form 4 and 14.5 × 14.5 × 19.3 cm for Form 3/+. Form 4 has the larger total volume and longer X and Z dimensions, while Form 3/+ retains a wider nominal Y dimension. The right answer depends on actual part orientation, repeat throughput, and the economics of keeping an older machine productive.
The decision in 30 seconds
Buy Form 4 if: deadlines, repeat jobs, multiple operators, remote monitoring, or lower print-cycle time have measurable value.
Consider Form 3+ if: you already own supported Form 3/+ workflow hardware or have a deeply discounted machine with documented condition, a known material lane, and acceptable replacement-consumable and service access.
Delay either purchase if: the resin queue, facility controls, washing, curing, waste handling, and acceptance criteria are not defined. A premium printer does not remove resin-process obligations.
Disclosure: GoodPrints may earn a commission from qualifying links on this page. This comparison uses current manufacturer-published specifications and claims; it does not claim hands-on testing.
Quick comparison
| Decision point | Formlabs Form 3+ | Formlabs Form 4 |
|---|---|---|
| Manufacturer-listed build volume | 14.5 × 14.5 × 19.3 cm; 4.05 L | 20.0 × 12.5 × 21.0 cm; 5.25 L |
| Published average print speed | 11 mm/hour across materials | 40 mm/hour across materials |
| Published speed range | 4-17 mm/hour depending on material | 15-100 mm/hour depending on material |
| Print engine | Laser and Light Processing Unit | Backlight Unit and LPU 4 |
| Remote visual monitoring | No camera listed | 5 MP camera; remote images and timelapses |
| Primary buying case | Verified legacy value or an existing installed workflow | Current professional throughput and workflow |
| Main overbuy or ownership risk | Cheap acquisition becomes expensive recovery | Premium workflow is unused by a light job queue |
Where Form 4 wins
Form 4 wins most new professional purchases because the upgrade case is operational. Formlabs says most prints finish in under two hours and publishes an average of 40 mm/hour across materials, compared with 11 mm/hour for Form 3/+. Those figures are manufacturer claims, not a promise for every geometry or material, but the gap is large enough to demand a queue-level test.
The platform also adds a camera for remote images, print history, and timelapses, plus a newer resin-handling and print-engine path. These features matter when several people share the machine, jobs have deadlines, or an operator needs evidence before walking back to the printer. Start with the Form 4 review and the Form 4 worth-it guide when current workflow is the main reason to buy.
Where Form 3+ can still make sense
Form 3+ can make sense as an already-owned machine with a qualified process, trained operators, compatible post-processing, and a stable material lane. It can also survive a used-buy audit when the purchase discount is substantial and the exact machine has documented condition and a realistic support path.
Do not treat the lower acquisition price as the full result. Ask for print history, maintenance records, included tanks and build platforms, current resin compatibility, software access, shipping protection, return terms, and a representative acceptance print. Confirm what Formlabs or a qualified reseller will support for that serial number and region. The Form 3+ review owns that deeper legacy-system check.
Run a ten-job throughput and fit audit
List ten representative jobs from the real queue. Record oriented part envelope, quantity, material, layer settings, support strategy, printer time, operator touch time, wash and cure time, finish requirement, inspection method, deadline, and the consequence of failure.
- Check oriented fit. Form 4 is not larger on every axis; use the actual supported orientation rather than comparing liters alone.
- Estimate accepted parts per day. Printer speed matters only after washing, curing, support removal, inspection, and reruns.
- Value the deadline difference. A faster printer is valuable when it shortens a design loop or prevents a missed production handoff.
- Measure operator intervention. Include setup, resin changes, cleanup, monitoring, documentation, and failed-job recovery.
- Repeat the test by material. Manufacturer-wide speed ranges do not replace a benchmark using the exact resin and representative geometry.
If Form 4 changes several current deadlines or produces materially more accepted output per staffed day, the upgrade has a measurable case. If the queue is light and Form 3+ already meets it, keeping a qualified system can be more rational than replacing it for specifications alone.
Used Form 3+ risk can erase the discount
A used professional printer is not automatically a bargain. Price the printer, freight, setup, tanks, cartridges, build platforms, wash-and-cure compatibility, facility controls, protective equipment, consumables, service, downtime, and the labor required to recover an undocumented process. Require a condition and acceptance plan before money changes hands.
A clean demo print is not enough. Use a part that exercises the intended material, height, supports, fine details, mating features, and finish. Define acceptance before the test. If the seller cannot provide a credible record or the machine cannot pass a representative job, the discount is speculative.
Build volume needs an orientation test
Form 4's listed 5.25 L build volume is about 30% larger than the Form 3/+'s 4.05 L. Yet the shape changes: Form 4 expands one planar dimension from 14.5 to 20.0 cm and Z from 19.3 to 21.0 cm, while the other planar dimension narrows from 14.5 to 12.5 cm. Long parts may fit Form 4 more naturally, while a specific square footprint can require a different rotation.
Export bounding boxes for the real supported orientations and add edge, support, and removal clearance. If standard Form 4 remains too small, compare Form 4 vs Form 4L rather than forcing a desktop machine to solve a large-format requirement.
Post-processing can remain the bottleneck
Faster printing does not guarantee faster finished parts. Washing, drying, curing, support removal, surface finishing, inspection, and waste handling may control the schedule. Map the complete resin cell and decide whether the current wash-and-cure capacity can absorb more printer output.
If the bench is not defined yet, read whether you need a wash-and-cure station and resin ventilation guidance. Follow the resin maker's safety documentation and applicable workplace and disposal rules.
Three buyer scenarios
A product-development team losing time to slow iteration
Choose Form 4 after a representative benchmark confirms that its faster print cycle shortens the full approved-part loop. Include queueing, wash, cure, inspection, and operator handoff rather than quoting printer speed alone.
A small shop offered a deeply discounted Form 3+
Consider it only if the condition, consumables, material path, service access, and acceptance print are documented. Walk away when the discount depends on optimistic recovery assumptions.
A hobby or occasional-use buyer wanting professional detail
Neither machine is automatically the best value. Compare the Form 4 vs Saturn 4 Ultra, Form 4 vs M7 Pro, and Form 4 vs GKtwo branches before paying for a workflow the queue will not use.
Before buying: prove the work belongs in-house
A Form 4 can be the stronger machine and still be the wrong business decision. Use the same ten representative jobs from the throughput audit to compare two complete paths: accepted parts made in-house and accepted parts supplied outside. Keep the file revision, material, orientation-sensitive features, finish, inspection, quantity, deadline, packaging, and approval state identical so the quote is testing the workload rather than a looser version of it.
| Choose this path | When it is the better fit | What must be proved |
|---|---|---|
| Own Form 4 | The queue is recurring, response time matters, and trained staff can keep the full resin cell productive. | Accepted output per staffed day, wash/cure capacity, inspection, safe handling, redundancy, and a defensible payback. |
| Keep Form 3+ | The installed process is qualified and still meets real deadlines without costly recovery work. | Condition, consumable and support access, representative-job capability, and the cost of remaining downtime. |
| Use outside production | Demand is occasional, unsettled, larger than the current cell, or expensive to staff and validate internally. | A scope-matched quote, sample or first article when needed, lead-time trigger, acceptance method, revision control, and repeat-order terms. |
Start with the buy-versus-print-service guide if ownership is still the real question. For a production-minded fit check, ask JC Print Farm whether the defined job belongs in its current production lane. If the file, material, quantity, finish, acceptance points, and timing are already clear, send that exact packet through the quote intake. A useful outside quote should sharpen the ownership decision even when you ultimately buy the printer.
Final recommendation
Buy Form 4 for a current professional workflow when the ten-job audit proves that faster cycles, remote visibility, newer consumables, and lower process friction create measurable value. It is the stronger new-purchase default for most teams comparing these two generations.
Keep or buy Form 3+ only when its legacy value is documented rather than assumed. An already-qualified installed machine can remain useful. A used purchase must survive condition, consumables, support, post-processing, labor, and acceptance testing. If it cannot, the lower price is not savings.
Frequently asked questions
Is Form 4 always faster than Form 3+?
Formlabs publishes much higher average and maximum print-speed figures for Form 4, but actual time depends on material, geometry, orientation, supports, and settings. Benchmark a representative job and measure the full finished-part cycle.
Does Form 4 have a larger build volume?
Yes in total listed volume: 5.25 L versus 4.05 L. The envelope is shaped differently, so check real supported orientation. Form 3/+ lists 14.5 cm on both planar axes, while Form 4 lists 20.0 by 12.5 cm.
Should I buy a used Form 3+?
Only when machine condition, print history, included hardware, consumable access, service path, shipping, return terms, and a representative acceptance print are satisfactory. Do not buy from acquisition price alone.
Should an existing Form 3+ owner upgrade?
Upgrade when repeat jobs show measurable deadline, throughput, monitoring, or operating-cost value. Keep the Form 3+ when it remains qualified, supported for the required workflow, and adequate for the actual queue.