Main trade-off
Brother MFC-L3720CDW
No automatic two-sided scanning or wired Ethernet connection.
Head-to-head
Brother MFC-L3720CDW vs MFC-L3780CDW: 3780 scans both sides without a second pass
The short answer
Choose the MFC-L3780CDW for double-sided originals, Ethernet or regular mixed-media work. The MFC-L3720CDW suits a Wi-Fi office scanning mostly single-sided pages, with less need for fast color batches.
Before you choose
The reasoning and the trade-offs
The same fifty sheets can represent different amounts of work
A 50-sheet two-sided packet contains 100 faces. The 3780 can capture both faces in one pass. The 3720 requires a separate workflow for the backs, despite having the same feeder capacity.
What this is based on
50 sheets x 2 faces=100 faces. Both 50 ADF, only 3780 single pass.
Main trade-off
Brother MFC-L3780CDW
The 30-sheet multipurpose tray is smaller than the main cassette.
Brother MFC-L3720CDW
- Choose it for
- Your scanned forms are single-sided
- Wi-Fi is enough for your shared printer
- Main trade-off
- No automatic two-sided scanning or wired Ethernet connection.
Brother MFC-L3780CDW
- Choose it for
- You scan both sides of documents regularly
- You need Ethernet and a multipurpose tray
- Main trade-off
- The 30-sheet multipurpose tray is smaller than the main cassette.
About this comparison
Compare two-sided scanning, Ethernet and special-media loading. See why the MFC-L3780CDW changes more than the speed of color printouts.
Choose the MFC-L3780CDW for double-sided originals, Ethernet or regular mixed-media work. The MFC-L3720CDW suits a Wi-Fi office scanning mostly single-sided pages, with less need for fast color batches.
Winner by situation
Start with what you need it to do
Two-sided contracts from several coworkers
Single-pass scanning avoids manually returning the stack.
- Brother MFC-L3720CDW
- Caution
- Brother MFC-L3780CDW
- Better fit
One-sided school handouts and occasional color copies
Both have a 50-sheet ADF and flatbed.
- Brother MFC-L3720CDW
- Good
- Brother MFC-L3780CDW
- Good
An office policy requires Ethernet
Only 3780 has the wired port.
- Brother MFC-L3720CDW
- Not suitable
- Brother MFC-L3780CDW
- Better fit
Short runs on a second supported paper stock
A 30-sheet multipurpose tray reduces repeated loading.
- Brother MFC-L3720CDW
- Caution
- Brother MFC-L3780CDW
- Better fit
What matters in practice
The differences that matter
The same fifty sheets can represent different amounts of work
A 50-sheet two-sided packet contains 100 faces. The 3780 can capture both faces in one pass. The 3720 requires a separate workflow for the backs, despite having the same feeder capacity.
How we reached this conclusion
50 sheets x 2 faces=100 faces. Both 50 ADF, only 3780 single pass.
The bypass tray matters for a mixed paper day
The 3780 pairs a 250-sheet main cassette with a 30-sheet multipurpose tray. That lets you keep ordinary paper loaded while feeding a supported alternate stock in a batch, instead of loading one sheet repeatedly.
How we reached this conclusion
3780 paper 250+30. 3720 paper 250+1. Media still subject manual.
A Wi-Fi upgrade will not add the missing scan hardware
The 3720 can share documents over Wi-Fi, but neither faster networking nor a software setting turns its simplex ADF into the 3780 single-pass scanner.
How we reached this conclusion
3720 duplex scan No. 3780 single pass duplex scan Yes.
Choice A
Brother, MFC-L3720CDW
MFC-L3720CDW
Color copying and single-sided document stacks in a Wi-Fi office.
- Best matched use
- Your scanned forms are single-sided
Checked facts
- Scanning both sides: Manual handling
- Ethernet: No
- Letter color speed: Up to 19 ppm
- Special-media input: One-sheet manual feed
Choice B
Brother, MFC-L3780CDW
MFC-L3780CDW
Double-sided paperwork and color charts on a shared network.
- Best matched use
- You scan both sides of documents regularly
Checked facts
- Scanning both sides: Single-pass automatic
- Ethernet: Gigabit Ethernet
- Letter color speed: Up to 31 ppm
- Special-media input: 30-sheet multipurpose tray
Meaningful differences
What changes the fit
| What changes | Brother MFC-L3720CDW | Brother MFC-L3780CDW | Why it matters |
|---|---|---|---|
| Scanning both sides | Manual handling | Single-pass automatic | The 3780 removes the return pass for supported two-sided originals. |
| Ethernet | No | Gigabit Ethernet | A wired office connection rules out the 3720. |
| Letter color speed | Up to 19 ppm | Up to 31 ppm | Longer color runs make the extra throughput more useful. |
| Special-media input | One-sheet manual feed | 30-sheet multipurpose tray | The 3780 reduces individual loading for supported media. |
| Document feeder | 50 sheets | 50 sheets | Both accept the same sheet count, but capture different numbers of faces automatically. |
What you give up
Every choice has a cost
If you choose Brother MFC-L3720CDW
- Its one-sheet manual feed is a limitation when alternating larger batches of paper stock.
If you choose Brother MFC-L3780CDW
- A scan packet above 50 suitable sheets needs more than one feeder load.
Recommendation switch
The decision flips if...
Incoming paperwork is often printed on both sides
Choose Brother MFC-L3780CDW. The duplex scanner addresses the actual bottleneck.
Your originals are single-sided and Wi-Fi is sufficient
Choose Brother MFC-L3720CDW. The 3720 covers that workflow if the saving is worthwhile.
You need an unattended 50-sheet batch on special stock
Choose neither. The 3780 multipurpose tray holds 30 sheets, not 50. Check media weight limits too.
What matters in practice
How to make the call
Incoming documents create the biggest difference
Both machines print on both sides automatically. The worthwhile upgrade is often on the input side, where the 3780 captures double-sided forms without requiring another manual pass.
Keep feeder capacity separate from scan speed
Both feeders accept 50 sheets, which can make the scanner specifications look similar. Face capture and pass count are different. A two-sided form archive strongly favors the 3780 even before print speed enters the decision.
A mixed-media tray can save repeated setup
For an office alternating plain reports with supported letterhead or heavier stock, the 3780 multipurpose tray is a practical advantage. It still requires the correct media setting and supported paper. A capacity figure is not permission to use any label or envelope.
Do not pay for a workflow you do not have
For a household printing short color jobs and scanning occasional one-sided sheets, the 3720 can be sufficient. Both use toner and separate maintenance consumables, so review the complete supply list before assuming either has a lower running cost.
What this comparison cannot tell you
- Rated print speeds are manufacturer figures, not matched hands-on tests.
- Toner yields use standardized test documents and vary with content.
What the facts say
What the comparison shows
Useful conclusions from the current laser printers comparison, followed by the checked facts used to reach them.
See the checked facts and calculation notes
| Product | Needs matched | Checked facts | Source records |
|---|---|---|---|
| Brother MFC-L3720CDW |
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| Brother MFC-L3780CDW |
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Ready to choose?
Check the price. Read the owner reviews.
Open either model on Amazon to check the current price, customer reviews and delivery options.
Brother MFC-L3720CDW
Your scanned forms are single-sided
See price & reviews on AmazonBrother MFC-L3780CDW
You scan both sides of documents regularly
See price & reviews on AmazonLinks open in a new tab.