Our take
The Acer K138ST combines a 1.7 lb chassis with a native WXGA image, RGB LED illumination, and a 0.8:1 short-throw ratio. Acer lists 800 ANSI lumens, giving the brightness profile a documented comparison value rather than an unqualified headline. Its small size makes it easier to move between rooms, though the spec sheet lists AC power, not battery operation. The short throw can reduce the distance needed for a picture, but it is not ultra-short-throw and still needs measured clearance. It suits a portable external-source setup in a dim room more naturally than a bright outdoor movie or an all-in-one streaming system.
A small-room portable projector for an external HDMI/MHL source when a short throw helps avoid a long setup distance..
Avoid it if built-in battery power, native Full HD, high ambient-light output, integrated streaming, or a true ultra-short-throw lens is essential.
Pros & cons
What could work for you, and what to consider before buying.
What works in its favor
- Acer documents native WXGA resolution and an ANSI-labeled 800-lumen output.
- The 0.8:1 lens is useful for shorter placement distances in small rooms.
- At 1.7 lb, it is easier to carry than a conventional classroom chassis.
What to weigh up
- AC operation means portability still depends on finding an outlet or separate power arrangement.
- A 0.8:1 lens is short-throw, not a projector designed to sit immediately beside the screen.
- Wireless projection accessories are optional and the sources do not establish built-in streaming apps.
Specifications and exact model details
The key details
| Model covered | K138ST |
|---|---|
| Image format | Native WXGA 1280 × 800; 800 ANSI lumens |
| Rated light output | 0.8:1 short-throw lens, RGB LED light source, 1.7 lb chassis, AC power |
| Placement | HDMI/MHL and VGA; two 3 W speakers; optional WirelessCAST or WirelessHD accessories |
Performance figures are manufacturer claims. Source checked October 15, 2026. Regional models and included accessories can differ.
Full review: how the features affect your choice
What the features mean for you
Small size helps when the setup changes
Acer's specification sheet gives the K138ST a weight of 1.7 lb and describes it as an ultra-portable projector. That makes it easier to move from a desk to a classroom cart or a small meeting room than a full-size lamp chassis. It is still a projector with a lens that must be aligned, a signal cable that must reach, and an AC power connection. Portable therefore describes its physical handling rather than a built-in battery. If it will be carried regularly, protect the lens, use a stable support, and include the necessary power adapter and HDMI or VGA cable in the carrying plan.
WXGA and 800 ANSI lumens set realistic expectations
Acer specifies a native 1280 × 800 WXGA image and 800 ANSI lumens. The native resolution works naturally with 16:10 laptop material but remains below Full HD for fine video detail. The ANSI figure is a model-specific manufacturer rating, yet 800 lumens is still modest compared with many large-room projectors. A smaller projected image and controlled ambient light will generally be easier to manage than a large picture with daylight in the room. Screen surface, picture mode, source quality, and LED age remain factors. Match the resolution and brightness to the actual audience, image size, and lighting instead of relying on portability alone.
Short-throw placement is helpful but not UST
The Acer sheet lists a 0.8:1 throw ratio and states that a 100-inch image can be produced at 1.7 metres. That is a meaningful short-throw arrangement for a small room where the projector cannot sit far back. It should not be described as ultra-short-throw: the lens still needs space from the screen, and the source does not document a near-wall UST installation. Measure the image diagonal and actual lens-to-screen distance before choosing a cart or mount. The geometry can also reduce the chance of someone walking through the beam, but alignment and keystone correction should not replace careful physical placement.
LED and optional wireless kits are separate facts
Acer identifies an RGB LED light source and offers WirelessCAST and WirelessHD as optional equipment. Those wireless accessories may provide additional source flexibility, but they are not evidence that every K138ST includes a wireless module, a streaming app platform, or a battery. The reviewed materials list HDMI/MHL and VGA for wired input. Check the actual bundle and the source device's compatibility before relying on wireless presentation. The sheet also lists two 3 W speakers, which can help with a small presentation but may not fill a larger room. Keep the product's included features distinct from optional accessories when judging its value.
Plan for external source and mains power
Acer lists HDMI/MHL and VGA and specifies AC power. That gives the K138ST a practical wired path from laptops and other compatible sources, but it is not a self-contained projector for a location without an outlet. Its optional wireless kits should be verified separately, and the product sheet does not establish built-in streaming. The portable design helps with carrying but does not remove cable planning, focus adjustment, or room-light considerations. Before use, confirm the outlet location, choose the image size, connect the source, and focus across the image. For frequent travel, pack the power supply carefully and protect the optical window from scratches or dust.
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Before you buy
Is the K138ST battery powered?
Acer specifies AC power; the reviewed sources do not establish built-in battery operation.
Is its 0.8:1 lens ultra-short-throw?
No. Acer describes a short-throw design; the 0.8:1 ratio is not classified here as UST.
Does it have built-in streaming apps?
The sources list wired inputs and optional wireless accessories but do not establish an onboard streaming platform.
Where can I check the current price?
Use the Amazon link for current offers. Check the exact model, seller, product condition, delivery, and return terms. This page does not display a live price or confirm stock.
Sources and review basis
Sources & review basis
We use the linked product documentation for the features above. Our suitability notes and buying advice are editorial judgments based on those features, not measured performance results.
- Acer-authored K138ST specification sheet ↗ — checked October 15, 2026.
- Acer-authored K138ST specification sheet ↗ — checked October 15, 2026.
- Acer K138ST launch announcement ↗ — checked October 15, 2026.
Is it the right fit?
Check the exact model and today’s offers on Amazon.