The catch
Brother DS-640
Each sheet goes in on its own, and scanning the back means a separate pass.
Side by side
Brother DS-640 vs DS-740D: 740D scans both sides in less rear paper space
Quick verdict
If you scan two-sided forms, or your desk leaves no room for paper to run far behind the scanner, get the DS-740D. The DS-640 will do for occasional single-sided receipts when saving money matters more to you than automatic back-side capture.
Before you buy
Why, and what it costs you
Scanning twenty two-sided forms takes twenty fewer insertions
Take 20 two-sided sheets. The DS-740D needs 20 insertions, while the DS-640 needs 40 passes through the feed slot to capture every face. Even if the pages feed quickly, the difference in repeated handling remains.
Where this comes from
The count presumes every sheet has two faces you want. Retries and software reordering are left out.
The catch
Brother DS-740D
It has neither a stack feeder nor a wireless connection.
Brother DS-640
- Why pick it
- Most of what you scan is single-sided receipts
- There's space behind the scanner for paper to run
- The catch
- Each sheet goes in on its own, and scanning the back means a separate pass.
Brother DS-740D
- Why pick it
- You often need both faces of signed forms scanned
- Your desk is shallow, so a supported return path helps
- The catch
- It has neither a stack feeder nor a wireless connection.
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What this page compares
Find out when two-sided forms and a shallow desk make the DS-740D worth it, and when the simpler DS-640 does the job for receipts beside a laptop.
If you scan two-sided forms, or your desk leaves no room for paper to run far behind the scanner, get the DS-740D. The DS-640 will do for occasional single-sided receipts when saving money matters more to you than automatic back-side capture.
Which one fits
Pick the situations that sound like you
A short evening session with two-sided school forms
No second insertion is needed for the DS-740D to capture the reverse.
- Brother DS-640
- Caution
- Brother DS-740D
- Better fit
Single-sided receipts now and then at a laptop
Each runs on USB power and takes one loose original at a time.
- Brother DS-640
- Good
- Brother DS-740D
- Good
Desk with a monitor stand at the back
For supported paper the return path may help, but measure the space for the cable and for loading.
- Brother DS-640
- Caution
- Brother DS-740D
- Better fit
A 40-sheet packet to run unattended
Neither model feeds a stack automatically.
- Brother DS-640
- Not suitable
- Brother DS-740D
- Not suitable
In practice
Differences you will notice
Scanning twenty two-sided forms takes twenty fewer insertions
Take 20 two-sided sheets. The DS-740D needs 20 insertions, while the DS-640 needs 40 passes through the feed slot to capture every face. Even if the pages feed quickly, the difference in repeated handling remains.
How we worked this out
The count presumes every sheet has two faces you want. Retries and software reordering are left out.
Desk depth can swing the better buy
On the DS-740D, a return lid sends suitable documents back over the scanner, so you do not need their full length of space behind it. That helps next to a monitor, though thicker media or anything outside the limits may still have to take the ordinary path.
How we worked this out
For Letter paper, Brother cites a saving of up to 11 inches. This is a claim about the paper path and does not guarantee clearance inside a cabinet.
No battery needed if the laptop is already on the desk
USB supplies both power and data on both models. If you scan at a laptop in hotel rooms or at a dining-room work area, neither needs a separate power adapter. The DS-740D is worth paying for because of its duplex handling. It does not depend on the computer any less.
How we worked this out
A compatible host workflow is required for each. Being powered over USB does not mean they scan to a phone on their own.
Option A
Brother, DS-640
DS-640
A small scanner that sits next to your laptop and handles receipts and the odd form.
- Best for
- Most of what you scan is single-sided receipts
Facts we checked
- Two-sided originals: Flip and feed through again
- Paper return lid: There is no DSD return lid
- Stack feeder: Takes one sheet at a time
- Power source: Computer USB port
Option B
Brother, DS-740D
DS-740D
Scans both sides of a loose form without you flipping it, and its return path suits a cramped desk.
- Best for
- You often need both faces of signed forms scanned
Facts we checked
- Two-sided originals: Both sides captured in one pass
- Paper return lid: A DSD return lid
- Stack feeder: Takes one sheet at a time
- Power source: Computer USB port
Spec by spec
Where they really differ
| Spec | Brother DS-640 | Brother DS-740D | In practice |
|---|---|---|---|
| Two-sided originals | Turn and feed again | Both sides in one pass | The DS-740D picks up a signed back page in the same pass. |
| Paper return lid | No DSD return lid | DSD return lid | With the DS-740D, suitable paper can stay nearer to the machine. |
| Stack feeder | One sheet at a time | One sheet at a time | Loading a whole packet is not automated on either. |
| Power source | USB from computer | USB from computer | Lacking an outlet does not force you into a battery model. |
Trade-offs
What each pick costs you
With Brother DS-640
- The scan has to land on a connected computer.
With Brother DS-740D
- Some media can't use the return path, so keep enough space free to feed straight through when needed.
Change of plan
When the answer changes
The forms you handle regularly carry information on the back
Go with Brother DS-740D. Each original no longer needs a second insertion with single-pass duplex.
You scan only a few one-sided receipts and can spend less by going with the DS-640
Go with Brother DS-640. You would rarely use the duplex feature.
You want to put a pile in and walk away while it scans
Neither model fits. Pick an ADF model, for example the ADS-1300.
Decision guide
How to decide
The DS-740D is the pick for two-sided forms or for a desk where paper can't extend far behind the scanner. Stay with the DS-640 for occasional single-sided receipts if the saving counts for more than automatic back-side capture.
Scanning twenty two-sided forms takes twenty fewer insertions
Take 20 two-sided sheets. The DS-740D takes 20 insertions to do them, while the DS-640 takes 40 passes through the feed slot to get every face. Even when the pages feed quickly, that is extra handling again and again. The count assumes every sheet has two faces you want, and it leaves out retries and any software reordering.
Desk depth can swing the better buy
The DS-740D's return lid sends suitable documents back over the top, so you do not need the full document length behind the scanner. That helps next to a monitor, though thicker media or anything outside the limits may still have to take the ordinary path. Brother describes a saving of up to 11 inches for Letter paper. Treat that as a claim about the paper path. It does not guarantee cabinet clearance.
No battery needed if the laptop is already on the desk
At a laptop in a hotel room or a dining-room work area, neither model needs a separate power adapter, because both take power and data from USB. What the DS-740D adds is duplex handling, so pay for that and not for more independence from the computer. Both still require a compatible host workflow, and USB power doesn't mean either scans to a phone on its own.
What this page can’t tell you
- Document preparation, OCR and saving time are left out of manufacturer feed ratings.
- Before you buy, confirm the supported media, the scan mode, your current operating system and the destination.
By the numbers
What the data shows
What we found across the document scanners we compare, plus the checked facts behind each finding.
Show the facts and the math
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| Brother DS-640 |
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| |
| Brother DS-740D |
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Ready to buy
See today’s price and what owners say
Open either model on Amazon for the current price, customer reviews and delivery options.
Brother DS-640
Most of what you scan is single-sided receipts
See price & reviews on AmazonBrother DS-740D
You often need both faces of signed forms scanned
See price & reviews on AmazonEach link opens in a new tab.
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