Main trade-off
Brother DS-640
Each sheet is fed individually and backs need a separate pass.
Head-to-head
Brother DS-640 vs DS-740D: 740D captures both sides with less rear paper space
The short answer
Choose the DS-740D for two-sided forms or a desk where paper cannot run far behind the scanner. The DS-640 is enough for occasional single-sided receipts if the saving matters more than automatic back-side capture.
Before you choose
The reasoning and the trade-offs
Twenty two-sided forms mean twenty fewer insertions
For 20 two-sided sheets, the DS-740D needs 20 insertions. The DS-640 needs 40 passes through the feed slot to capture every face. That is a repeated handling difference even when the pages feed quickly.
What this is based on
Count assumes each sheet has two wanted faces. It excludes retries and any software reordering.
Main trade-off
Brother DS-740D
There is no stack feeder or wireless connection.
Brother DS-640
- Choose it for
- Your originals are mostly single-sided receipts
- You have room behind the scanner for paper
- Main trade-off
- Each sheet is fed individually and backs need a separate pass.
Brother DS-740D
- Choose it for
- You regularly scan both faces of signed forms
- A supported return path helps on your shallow desk
- Main trade-off
- There is no stack feeder or wireless connection.
About this comparison
See when two-sided forms and a shallow desk justify the DS-740D, and when the simpler DS-640 is enough for receipts beside a laptop.
Choose the DS-740D for two-sided forms or a desk where paper cannot run far behind the scanner. The DS-640 is enough for occasional single-sided receipts if the saving matters more than automatic back-side capture.
Winner by situation
Start with what you need it to do
Two-sided school forms in a short evening session
The DS-740D captures the reverse without another insertion.
- Brother DS-640
- Caution
- Brother DS-740D
- Better fit
Occasional single-sided receipts at a laptop
Both are USB-powered and accept one loose original at a time.
- Brother DS-640
- Good
- Brother DS-740D
- Good
Desk backed by a monitor stand
The return path can help for supported paper, but measure cable and loading space.
- Brother DS-640
- Caution
- Brother DS-740D
- Better fit
A 40-sheet packet to leave unattended
Neither has an automatic stack feeder.
- Brother DS-640
- Not suitable
- Brother DS-740D
- Not suitable
What matters in practice
The differences that matter
Twenty two-sided forms mean twenty fewer insertions
For 20 two-sided sheets, the DS-740D needs 20 insertions. The DS-640 needs 40 passes through the feed slot to capture every face. That is a repeated handling difference even when the pages feed quickly.
How we reached this conclusion
Count assumes each sheet has two wanted faces. It excludes retries and any software reordering.
A short desk can change the better buy
The DS-740D's return lid brings suitable documents back over the scanner instead of requiring their full length behind it. This is useful beside a monitor, but thicker or out-of-limit media may still require the ordinary path.
How we reached this conclusion
Brother describes a saving of up to 11 inches for Letter paper. That is a paper-path claim, not a guarantee of cabinet clearance.
A battery is unnecessary when the laptop is already there
Both models take power and data from USB. If you scan at a laptop in hotel rooms or a dining-room work area, either avoids a separate power adapter. Pay for the DS-740D's duplex handling rather than expecting it to be more independent of the computer.
How we reached this conclusion
Both require a compatible host workflow. USB power does not mean they scan to a phone by themselves.
Choice A
Brother, DS-640
DS-640
Keep a small scanner beside your laptop for receipts and occasional forms.
- Best matched use
- Your originals are mostly single-sided receipts
Checked facts
- Two-sided originals: Turn and feed again
- Paper return lid: No DSD return lid
- Stack feeder: One sheet at a time
- Power source: USB from computer
Choice B
Brother, DS-740D
DS-740D
Capture both faces of a loose form without turning it, with a return path for a cramped desk.
- Best matched use
- You regularly scan both faces of signed forms
Checked facts
- Two-sided originals: Both sides in one pass
- Paper return lid: DSD return lid
- Stack feeder: One sheet at a time
- Power source: USB from computer
Meaningful differences
What changes the fit
| What changes | Brother DS-640 | Brother DS-740D | Why it matters |
|---|---|---|---|
| Two-sided originals | Turn and feed again | Both sides in one pass | A signed back page becomes part of the same pass on the DS-740D. |
| Paper return lid | No DSD return lid | DSD return lid | The DS-740D can keep suitable paper closer to the machine. |
| Stack feeder | One sheet at a time | One sheet at a time | Neither automates loading a whole packet. |
| Power source | USB from computer | USB from computer | An outlet shortage does not require buying a battery model. |
What you give up
Every choice has a cost
If you choose Brother DS-640
- A connected computer is needed to receive the scan.
If you choose Brother DS-740D
- The return path has media restrictions, so leave room to use straight feeding when required.
Recommendation switch
The decision flips if...
Your regular forms have information on the back
Choose Brother DS-740D. Single-pass duplex removes the extra insertion for each original.
You only scan a few one-sided receipts and can save on the DS-640
Choose Brother DS-640. The duplex feature would be used infrequently.
You want to load a pile and leave it scanning
Choose neither. Choose an ADF model such as the ADS-1300.
What matters in practice
Before you choose
What this comparison cannot tell you
- Manufacturer feed ratings do not include document preparation, OCR or saving time.
- Confirm the supported media, scan mode, current operating system and destination before purchase.
What the facts say
What the comparison shows
Useful conclusions from the current document scanners 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 DS-640 |
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| Brother DS-740D |
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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 DS-640
Your originals are mostly single-sided receipts
See price & reviews on AmazonBrother DS-740D
You regularly scan both faces of signed forms
See price & reviews on AmazonLinks open in a new tab.