ComfyUI-ResolutionTools

Resolution maths for latent-space models, done exactly.

Two nodes, no dependencies:

Node	Does
Resolution Selector (Real MP)	aspect ratio + real megapixels → grid-aligned width/height, ratio held exact
Align Resolution to Grid	snap an arbitrary size onto the grid (1920×1080 → 1920×1088)

Why

1. "Megapixels" usually isn't megapixels

ComfyUI's built-in Resolution Selector computes megapixels * 1024 * 1024. That's mebipixels — every value you type is inflated 4.86% in area. Ask for 2.36 MP at 9:16 and you get 1184×2096 = 2.48 real MP.

This node uses megapixels * 1_000_000. Ask for 2.36 and you get 2.36.

2. Rounding each axis independently drifts the aspect ratio

That same 1184×2096 has a ratio of 0.5649. True 9:16 is 0.5625. Both axes were individually snapped to a multiple of 16, and the ratio fell between the cracks.

With exact_ratio on (the default), this node solves on the lattice of sizes that are simultaneously grid-aligned and exactly on-ratio. For a reduced ratio a:b and alignment m, those are exactly (a·L·n, b·L·n) where

L = lcm(m / gcd(a, m), m / gcd(b, m))

so it picks n = round(sqrt(target_px / (a·b·L²))). For 9:16 at m=16 the lattice is 144n × 256n, and n=8 gives 1152×2048 — exact 9:16, on the grid, 2.36 MP.

Turn exact_ratio off to get the old independent-rounding behaviour when you'd rather hit the area target precisely and don't care about a hair of ratio drift.

3. Getting alignment wrong bands the bottom of your image

A latent-space DiT reaches pixels through two reductions:

pixels ──/ VAE spatial downscale ──> latent ──/ DiT patch size ──> tokens

Both axes must be multiples of vae_downscale × patch_size:

Models	Alignment
Krea 2, Flux, SD3, Qwen-Image, Wan	16	8 × 2
MiniMax H3	32	16 × 2
SDXL, SD1.5 (UNet, 3 downsample stages)	64	universally safe

Miss it and comfy.ldm.common_dit.pad_to_patch_size pads the latent up to the patch grid using circular padding — the pad row is a wrapped copy of the top of the image. That fabricated row gets folded into the same patch token as the real bottom row, a combination the model never saw in training, so the final latent row decodes to garbage: a band along the bottom edge, 8 px tall on Krea 2, 16 px on H3. Padding is only ever appended, so the artifact is always bottom/right, never top/left.

This is why 1920×1080 bands on Krea 2 (1080/8 = 135 latent rows, odd) and 1920×1088 doesn't (1088/8 = 136, even). The built-in selector defaults multiple to 8, which walks you straight into it.

Reference resolutions

All values below are real megapixels. If you're migrating from a table computed with the built-in selector, every label in it is ~4.86% low — a row marked "2.0 MP" there is really 2.09.

Exact-ratio tables (exact_ratio = true)

These are the complete set of true-16:9 grid-aligned resolutions. There is nothing valid between the rows: the lattice is 256n × 144n at alignment 16 and 512n × 288n at alignment 32. Type the listed megapixels and you get that row back.

Krea 2 — alignment = 16:

megapixels	Aspect	Output (alignment=16)
0.15	16:9	512 x 288
0.33	16:9	768 x 432
0.59	16:9	1024 x 576
0.92	16:9	1280 x 720
1.33	16:9	1536 x 864
1.81	16:9	1792 x 1008
2.36	16:9	2048 x 1152
2.99	16:9	2304 x 1296
3.69	16:9	2560 x 1440
4.46	16:9	2816 x 1584

MiniMax H3 — alignment = 32:

megapixels	Aspect	Output (alignment=32)
0.15	16:9	512 x 288
0.59	16:9	1024 x 576
1.33	16:9	1536 x 864
2.36	16:9	2048 x 1152
3.69	16:9	2560 x 1440
5.31	16:9	3072 x 1728

Five rows to 4 MP is genuinely all there is on a 32-grid — which is why none of the commonly circulated H3 resolution tables are actually 16:9.

Area-target tables (exact_ratio = false)

For when you want a specific pixel budget more than a perfect ratio. Each axis is rounded independently, so the ratio drifts a little.

Krea 2 — alignment = 16:

megapixels	Aspect	Output (alignment=16)
0.2	16:9	592 x 336
0.3	16:9	736 x 416
0.4	16:9	848 x 480
0.5	16:9	944 x 528
0.6	16:9	1040 x 576
0.7	16:9	1120 x 624
0.8	16:9	1200 x 672
0.9	16:9	1264 x 704
1.0	16:9	1328 x 752
1.2	16:9	1456 x 816
1.4	16:9	1584 x 880
1.6	16:9	1680 x 944
1.8	16:9	1792 x 1008
2.0	16:9	1888 x 1056
2.25	16:9	2000 x 1120
2.5	16:9	2112 x 1184
2.75	16:9	2208 x 1248
3.0	16:9	2304 x 1296
3.25	16:9	2400 x 1360
3.5	16:9	2496 x 1408
3.75	16:9	2576 x 1456
4.0	16:9	2672 x 1504

MiniMax H3 — alignment = 32:

megapixels	Aspect	Output (alignment=32)
0.2	16:9	608 x 320
0.3	16:9	736 x 416
0.4	16:9	832 x 480
0.5	16:9	928 x 544
0.6	16:9	1024 x 576
0.7	16:9	1120 x 640
0.8	16:9	1184 x 672
0.9	16:9	1280 x 704
1.0	16:9	1344 x 736
1.2	16:9	1472 x 832
1.4	16:9	1568 x 896
1.6	16:9	1696 x 960
1.8	16:9	1792 x 992
2.0	16:9	1888 x 1056
2.25	16:9	1984 x 1120
2.5	16:9	2112 x 1184
2.75	16:9	2208 x 1248
3.0	16:9	2304 x 1312
3.25	16:9	2400 x 1344
3.5	16:9	2496 x 1408
3.75	16:9	2592 x 1440
4.0	16:9	2656 x 1504

Ratio drift is under 1% for most Krea 2 rows, but gets bad on H3 at the low end — 6.9% at 0.2 MP, where a 32 px step is a large fraction of a 320 px axis. Below about 0.6 MP on H3, use the exact lattice instead.

Other ratios at ~2.36 MP (Krea 2, alignment = 16)

megapixels	Aspect	Output (alignment=16)
2.36	1:1	1536 x 1536
2.36	16:9	2048 x 1152
2.36	9:16	1152 x 2048
2.22	3:2	1824 x 1216
2.22	2:3	1216 x 1824
2.24	4:3	1728 x 1296
2.24	3:4	1296 x 1728
2.37	21:9	2352 x 1008
2.37	9:21	1008 x 2352

Picking a row

Krea 2 — the official envelope is a 1K–2K long edge, so 2.36 MP (2048×1152) is the top of sanctioned territory. The 2.99 and 3.69 rows are extrapolation: expect detail repetition rather than sharper eyes.

MiniMax H3 — the native canvas is a 768 short edge, 768×1344 ≈ 1.03 MP (BASE_SHORT_EDGE / MAX_PIXELS in comfy_extras/nodes_minimax_h3.py), and 1344×768 is the node default. 1.33 MP (1536×864) is a mild ~29% stretch and the highest row worth running by default. 2.36 MP is 2.3× the trained area and 3.69 MP is 3.6×; motion coherence degrades before sharpness improves.

Nodes

Resolution Selector (Real MP)

Inputs — aspect_ratio (11 presets + Custom), megapixels (real, 10⁶), alignment (default 16), exact_ratio (default on), custom_w / custom_h (advanced, for the Custom ratio).

Outputs — width, height, megapixels (what it actually produced), label ("1152x2048", useful for filename prefixes).

Align Resolution to Grid

Inputs — width, height, alignment, mode (round / up / down).

Outputs — width, height, changed (true if anything was off-grid), label.

Use up when you must not lose framing, down when you must not exceed a budget.

Install

Via ComfyUI-Manager, or:

cd ComfyUI/custom_nodes
git clone https://github.com/dreevelle/ComfyUI-ResolutionTools

No dependencies, no restart quirks — it's pure stdlib maths.

License

MIT