FLUX 3 Klein: int8 vs bf16
FLUX 3 Klein ships for ComfyUI in bf16 (11.1 GB) and int8 (5.8 GB). Does int8 cost quality?
Setup: distilled checkpoint, 16 steps, 1 MP, RTX 5090. Transformer and text encoder in the same precision. Same prompt and seed in every pair.
Tap a picture to switch between int8 and bf16.
Simple to advanced
Prompt
A red apple on a table.
Prompt
Close-up photograph of a ginger tabby cat asleep on a sunlit windowsill, soft morning light.
Prompt
Close-up photograph of an elderly Japanese fisherman in his seventies with weathered brown skin, deep wrinkles around his eyes and a short white stubble beard, wearing a faded indigo cotton jacket. He holds a coiled hemp rope in both calloused hands at chest height and looks straight into the camera. Soft overcast daylight from frame-left, a blurred grey harbour wall behind him. Shot on an 85mm lens at f/2, natural colour, fine film grain.
Prompt
Full-color outdoor photograph of an alpine valley at dawn, shot from a high ridge. In the foreground, frost-covered tufts of grass and a lichen-spotted granite boulder; in the midground, a winding turquoise river cuts through a pine forest with a small wooden footbridge; in the background, three jagged snow-capped peaks catch pink first light while low mist fills the valley floor. Crisp, cold air, long shadows, deep focus from front to back.
Prompt
Anime illustration in a clean modern cel-shaded style with crisp black linework and flat colours. A teenage girl with short silver hair and amber eyes, wearing an oversized yellow raincoat and red rubber boots, stands on a rain-soaked Tokyo side street at night holding a clear umbrella. Neon signs in pink and cyan reflect in the puddles around her feet. Low camera angle, frame-centred, falling rain drawn as thin white streaks.
Prompt
Flat graphic design poster for a jazz festival, straight-on. A deep navy background with a large stylised golden saxophone curving diagonally from lower left to upper right. Across the top in bold cream condensed sans-serif capitals: "BLUE NOTE NIGHTS". Below it, smaller in a thin gold serif: "Summer Jazz Festival 2026". Along the bottom edge in small white sans-serif type: "July 18–20 · Riverside Park · Tickets at the door". Subtle paper grain texture, screen-print look with slight misregistration.
Prompt
Full-color indoor photograph of a busy bakery counter in the morning. On the left, a young Black woman baker in a white apron and a flour-dusted blue cap slides a tray of six golden croissants into a glass display case. In the centre, the display case holds three rows of pastries: cinnamon rolls on top, fruit tarts with glazed strawberries in the middle, and chocolate éclairs at the bottom. On the right, an older white man with grey hair and round glasses, in a green wool coat, points at the tarts while holding a brown paper bag. Behind the counter, a chalkboard menu reads "TODAY: RYE 4.50 / SOURDOUGH 5.00". Warm light from pendant lamps, slight steam rising from a coffee machine in the background.
Prompt
Studio photograph of a luxury wristwatch lying on black slate. The watch has a brushed titanium case, a sapphire crystal with a faint blue anti-reflective tint, and a deep green dial in #0B5D3B with applied silver hour markers and a small date window at three o'clock showing "17". The strap is tan stitched leather curving off frame-right. A single hard key light from the upper left throws a crisp highlight along the bezel; water droplets bead on the slate around it. Macro lens, shallow depth of field, the crown in sharp focus.
Prompt
Full-color outdoor photograph of a quiet seaside café terrace at golden hour, eye level. A round white marble table <table_1> stands in the lower centre with a cappuccino cup <cup_1> on it. On the left, a woman <woman_1> sits reading a paperback. On the right, a sleeping dalmatian dog <dog_1> lies on the terracotta tiles. In the background, the calm sea <sea_1> stretches to the horizon under a peach sky, and a striped red-and-white awning <awning_1> runs along the top edge. [{"id": "awning_1", "bbox": [0, 0, 120, 1000], "desc": "A scalloped canvas awning with vertical red and white stripes."}, {"id": "sea_1", "bbox": [150, 0, 450, 1000], "desc": "A calm turquoise sea with small glints of low sunlight and a soft horizon line."}, {"id": "woman_1", "bbox": [280, 40, 900, 380], "desc": "A woman in her thirties with light olive skin and dark curly shoulder-length hair, wearing a cream linen dress and gold hoop earrings, seated in a rattan chair, reading a paperback held in both hands."}, {"id": "table_1", "bbox": [560, 380, 900, 640], "desc": "A small round white marble café table on a black wrought-iron base."}, {"id": "cup_1", "bbox": [520, 460, 600, 560], "desc": "A white porcelain cappuccino cup on a saucer with heart-shaped latte art."}, {"id": "dog_1", "bbox": [700, 640, 960, 980], "desc": "A dalmatian lying curled up asleep, white coat with black spots, chin resting on its front paws."}]
At 100 %
Prompt
Flat graphic design poster for a jazz festival, straight-on. A deep navy background with a large stylised golden saxophone curving diagonally from lower left to upper right. Across the top in bold cream condensed sans-serif capitals: "BLUE NOTE NIGHTS". Below it, smaller in a thin gold serif: "Summer Jazz Festival 2026". Along the bottom edge in small white sans-serif type: "July 18–20 · Riverside Park · Tickets at the door". Subtle paper grain texture, screen-print look with slight misregistration.
Prompt
Close-up photograph of an elderly Japanese fisherman in his seventies with weathered brown skin, deep wrinkles around his eyes and a short white stubble beard, wearing a faded indigo cotton jacket. He holds a coiled hemp rope in both calloused hands at chest height and looks straight into the camera. Soft overcast daylight from frame-left, a blurred grey harbour wall behind him. Shot on an 85mm lens at f/2, natural colour, fine film grain.
Prompt
Studio photograph of a luxury wristwatch lying on black slate. The watch has a brushed titanium case, a sapphire crystal with a faint blue anti-reflective tint, and a deep green dial in #0B5D3B with applied silver hour markers and a small date window at three o'clock showing "17". The strap is tan stitched leather curving off frame-right. A single hard key light from the upper left throws a crisp highlight along the bezel; water droplets bead on the slate around it. Macro lens, shallow depth of field, the crown in sharp focus.
Prompt
Anime illustration in a clean modern cel-shaded style with crisp black linework and flat colours. A teenage girl with short silver hair and amber eyes, wearing an oversized yellow raincoat and red rubber boots, stands on a rain-soaked Tokyo side street at night holding a clear umbrella. Neon signs in pink and cyan reflect in the puddles around her feet. Low camera angle, frame-centred, falling rain drawn as thin white streaks.
Same sharpness. The neon signs differ, but both are made-up lettering, neither is worse.
Edits
"Replace the brown horse with a large white camel …" seed 314159Prompt
Replace the brown horse with a large white camel with a shaggy cream coat and two humps, walking at the same angle toward frame-right with the astronaut seated between the humps, holding the same leather reins. Its long legs kick up small plumes of grey moon dust and cast long blue-grey shadows to the left. Keep the astronaut, the Earth on the right, the lunar surface, the distant spacecraft and the black starry sky unchanged.
"Change the headline to 'ICED TEA STAND!' …" seed 314159Prompt
Change the large headline "LEMONADE STAND!" to "ICED TEA STAND!" in the same rounded yellow bubble letters with dark blue outlines and orange drop shadows, and change the glass the girl holds to amber iced tea with ice cubes and a lemon wheel. Keep every other text, both children, the counter, the menu panels and the layout identical.
"Change the rain outside the window to heavy snowfall …" seed 314159Prompt
Change the view through the window on the right from a rainy evening to a heavy snowfall at night: thick snowflakes falling past the glass, snow piled on the window ledge and the street outside, and the passing umbrellas replaced by people in winter coats with snow on their shoulders. Cool blue light from the snowy street mixes with the warm lamplight inside. Keep the bookshelves, armchairs, reading table, the woman at the counter and the camera framing unchanged.
Numbers
| int8 | bf16 | |
|---|---|---|
| Text to image | 2.5 s | 5–6.5 s |
| Edit | 4 s | 10–11 s |
| VRAM | ~11 GB | 18–20 GB |
| PSNR vs bf16 (median) | 27 dB t2i, 33 dB edit | — |
int8 is half the memory and twice as fast on this card.
The prompt upsampler matters more
BFL also ships a 9.7 GB prompt upsampler (a Qwen3.5-9B fine-tune) that turns a short request into a long caption. Tap to compare:
Upsampled caption
Flat 2D illustrated poster for a kid’s lemonade stand, rendered in bright hand-painted shapes on a pale yellow background with a scalloped white border and small doodles of green leaves around the edges. Across the top, large rounded bubble letters read "LEMONADE STAND!" in sunny yellow with dark blue outlines, each letter casting a short orange drop shadow. Beneath the title, smaller red uppercase text reads "TASTY LEMON DRINKS FOR YOU!" In the center, a cheerful cartoon girl stands behind a striped turquoise-and-white counter beneath a triangular sign reading "KID'S LEMONADE". She has brown skin, curly dark hair tied into two puffs, and wears a white apron over a pink shirt; she holds up a clear glass filled with pale yellow lemonade, ice cubes, a lemon wheel, and a striped straw. Beside her sits a smiling cartoon boy with fair skin, short red hair, round glasses, and a mint-green apron, pouring lemonade from a glass pitcher into a cup. Three oversized lemons rest along the front of the counter beside a jar labeled "LIME", a jar labeled "MINT", and a stack of paper cups marked "$1". Below them, four colorful menu panels read "CLASSIC LEMONADE — $1", "BERRY LEMONADE — $2", "FROSTED LEMONADE — $3", and "FREE REFILL WITH A TASTER CUP". At the bottom, bold navy text reads "SATURDAY • 10 AM–4 PM" above "COME BY THE GARDEN LEARNING HALL!" Small illustrations of sliced lemons, cherries, straws, bubbles, and tiny stars fill the corners without crowding the wording.
Upsampled caption
Full-color indoor photograph, eye-level wide view of a small bookshop on a rainy evening, lit by amber pendant lamps and shaded wall sconces. In the foreground, dark wooden floorboards reflect patches of warm light beneath a worn red rug patterned with muted green leaves. A low oak reading table sits left of center with an open hardcover book, two stacked paperbacks, a ceramic mug releasing steam, and a brass-shaded lamp casting a pool of yellow light across the pages. Two mismatched armchairs face each other beside it: one upholstered in moss-green velvet and another covered in rust-colored corduroy, each holding a folded wool blanket. On the right, a narrow window is crowded with raindrops and thin streams of water running down the glass; beyond it, wet pavement reflects blue-grey streetlights, blurred car headlights, and the silhouettes of passing umbrellas. The shop’s tall front windows are framed by shelves packed edge to edge with books. Across the back wall, long wooden bookcases rise nearly to the ceiling, their uneven rows filled with clothbound volumes in faded burgundy, navy, ochre, brown, and forest green. Small handwritten shelf labels read "FICTION", "POETRY", "MYSTERY", and "HISTORY" in cream serif lettering. Near the upper center hangs a round sign painted deep green with gold serif text reading "BOOKS & RAIN". At frame-left, a compact checkout counter holds a chipped wooden cash box, a stack of returned books tied with cotton string, and a card reader. Behind it stands a white woman in her forties with fair skin and wavy chestnut hair pinned loosely at the nape, wearing a charcoal cardigan over a cream blouse as she reaches toward a shelf. Warm pools of lamplight leave the corners dim, while potted ferns sit among the lower shelves and a radiator below the rain-streaked window carries a damp umbrella resting against its side.
Upsampled caption
Photorealistic digital illustration of an astronaut riding a horse across the moon, viewed from a low three-quarter angle with a deep depth of field. In the center, a white male astronaut in his thirties sits upright on a dark bay horse galloping toward frame-right. He wears a bulky white extravehicular spacesuit with grey joint panels, red safety markings, thick gloves, heavy boots, and a reflective gold visor that completely conceals his face; a compact life-support pack rises behind his shoulders. His gloved hands hold taut brown leather reins as he leans forward over the saddle. The horse has a black mane and tail blown backward by its motion, muscular legs extended at different points in a running stride, and pale lunar light glinting along its coat. A fitted silver saddle blanket lies beneath a rigid metallic saddle designed for space travel, with small fastening straps crossing the horse’s flanks. Below them, the ground is covered in powdery grey regolith marked by hoofprints, boot prints, shallow craters, and long blue-grey shadows stretching to the left. On the far right horizon, Earth hangs above the cratered surface as a bright blue-and-white sphere. In the background, a dense black sky contains scattered stars and the curved edge of the Moon runs across the lower third. Near the upper left, a distant spacecraft rests beside two planted flagpoles, reduced to a small angular silhouette against the darkness.
- Text goes from garbled to correct, and detail goes way up. 3–5 s per prompt.
- It invents things, like jars labelled “LIME” and “MINT”.
- Two seeds of an upsampled prompt look nearly the same.
Two gotchas
- A hex colour gets printed. “A dial in #0B5D3B” put
#0B5D33on the dial. Name colours in words. - Don’t edit with the seed that made the picture. The edit lands back on the original:
Prompt
Replace the brown horse with a large white camel with a shaggy cream coat and two humps, walking at the same angle toward frame-right with the astronaut seated between the humps, holding the same leather reins. Its long legs kick up small plumes of grey moon dust and cast long blue-grey shadows to the left. Keep the astronaut, the Earth on the right, the lunar surface, the distant spacecraft and the black starry sky unchanged.
Verdict
int8 is my default now: no visible loss, half the memory, twice the speed. Spend the effort on the prompt instead.