GUIDES › FDM VS SLA
TECHNOLOGY COMPARISON
FDM VS SLA
An honest comparison of the two most common 3D printing technologies. Neither is universally better — the right choice depends on what you're making and what properties matter most.
AT A GLANCE
QUICK OVERVIEW
FDM — FILAMENT
Melts plastic filament and deposits it layer by layer through a heated nozzle.
• Layer height: 100-300 microns
• Build volume: up to 256 x 256 x 256mm
• Materials: PLA, PETG, ABS, TPU, ASA, Nylon...
• Infill: variable (saves material)
• Post-processing: optional
SLA — RESIN
Cures liquid resin with UV light, building parts layer by layer from a vat.
• Layer height: 25-100 microns
• Build volume: up to 218 x 122 x 220mm
• Materials: standard, tough, flexible, high-temp resin
• Structure: fully solid (no infill)
• Post-processing: required (wash + UV cure)
HEAD TO HEAD
DETAILED COMPARISON
| PROPERTY | FDM | SLA |
|---|---|---|
| SURFACE FINISH | Visible layer lines. Can be sanded/smoothed but requires effort. | Smooth, near injection-mould finish straight off the printer. ADVANTAGE: SLA |
| FINE DETAIL | Limited by nozzle size (0.4mm typical). Small features may be lost. | Excellent — captures fine text, textures, and small features down to ~50 microns. ADVANTAGE: SLA |
| IMPACT STRENGTH | Good to excellent. PETG and ABS absorb impacts well. Parts flex before breaking. ADVANTAGE: FDM | Poor. Standard resin is brittle and shatters under impact. Tough resin improves this but still trails FDM. |
| TENSILE STRENGTH | Moderate to high, depending on material and print orientation. Layer adhesion is the weak point. | Moderate. Isotropic (equal strength in all directions) since parts are fully solid. But lower elongation at break. DEPENDS ON MATERIAL |
| DURABILITY | Excellent long-term durability. PLA is stable indoors. PETG/ASA handle outdoor use. ADVANTAGE: FDM | Degrades in UV sunlight over time — yellowing and embrittlement. Best for indoor use or coated parts. |
| HEAT RESISTANCE | Varies by material. PLA softens at ~60°C. ABS/ASA handles ~100°C. | Standard resin softens at ~60-70°C. Specialty high-temp resin can handle up to 200°C. DEPENDS ON MATERIAL |
| MATERIAL RANGE | Extensive — PLA, PETG, ABS, TPU, ASA, Nylon, carbon-fibre composites, and more. ADVANTAGE: FDM | More limited — standard, tough, flexible, castable, and high-temp resins. |
| BUILD SIZE | Larger — our build volume is 256 x 256 x 256mm. ADVANTAGE: FDM | Smaller — our build volume is 218 x 122 x 220mm. |
| COST | Lower cost per part. Variable infill saves material on larger prints. ADVANTAGE: FDM | Typically 2-3x FDM for the same volume. Parts are fully solid so use more material. |
| POST-PROCESSING | Optional. Support removal and optional sanding/painting. ADVANTAGE: FDM | Mandatory. Every print requires IPA wash and UV curing. Adds time and cost. |
COMMON MISCONCEPTION
IS SLA STRONGER THAN FDM?
A common claim is that SLA is stronger because prints are fully solid. The reality is more nuanced.
WHAT SLA DOES WELL
• Isotropic strength — equal in all directions (no weak layer lines)
• High stiffness and rigidity
• Excellent dimensional accuracy under load
• Good compressive strength
WHERE FDM WINS
• Impact resistance — FDM parts flex and absorb energy, resin shatters
• Elongation at break — FDM materials stretch further before failure
• Fatigue resistance — better for parts under repeated stress
• Long-term durability — no UV degradation concern
Bottom line: For functional parts that need to survive drops, impacts, or repeated use, FDM with PETG or ABS is generally the better choice. SLA excels at stiffness, detail, and dimensional precision — but standard resin is brittle and will crack under sudden force.
DECISION GUIDE
CHOOSE YOUR TECHNOLOGY
CHOOSE FDM WHEN...
• Your part needs to survive drops or impacts
• You need a specific material (PETG, ABS, TPU, Nylon)
• The part will be used outdoors or in sunlight
• You need a large part (over 200mm in any dimension)
• Budget is a priority and surface finish is secondary
• The part will see repeated mechanical stress
• You're making functional prototypes or jigs
CHOOSE SLA WHEN...
• You need fine detail — text, textures, small features
• Surface finish must be smooth without post-processing
• You're printing miniatures, figurines, or models
• Dimensional accuracy and crisp edges are essential
• The part is a visual prototype or display piece
• You need jewellery casting masters or dental models
• The part will be kept indoors and handled gently
Not sure? FDM is the safe default for most projects. Choose SLA when surface quality or fine detail is the primary requirement.
PRICING
COST COMPARISON
| FACTOR | FDM | SLA |
|---|---|---|
| MATERIAL COST | Lower — filament is cheaper per gram. Variable infill reduces usage. | Higher — resin costs more and parts are fully solid. |
| STARTING PRICE | From ~£3 for small parts | From ~£12 for small parts |
| POST-PROCESSING | Included — support removal is straightforward | Included — wash + UV cure adds time and consumables |
| BEST VALUE | Large parts, functional prototypes, batch production | Small, detailed parts where finish justifies the premium |
COMPARE PRICES INSTANTLY
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