Most file conversion pricing is quoted per conversion, per minute, or per month — not per gigabyte. But GB-based benchmarks help you compare apples to apples when your workflow processes files of varying sizes.
This guide calculates effective cost per gigabyte for the most common file types across major providers, using April 2026 pricing and realistic file size assumptions. All figures are estimates — check each provider's current pricing before budgeting.
TL;DR — cost per GB by format type
Effective cost per GB processed (April 2026 estimates, assumes average file sizes and moderate volume):
| Format type | Avg file size | CloudConvert (PAYG) | ChangeThisFile ($29 Hobby) | AWS MediaConvert |
|---|---|---|---|---|
| JPG/PNG images | ~2 MB | $2.40/GB (1-min floor!) | $0.29/GB (at 10K/mo) | N/A (images not supported) |
| DOCX→PDF | ~500 KB | $9.60/GB (1-min floor) | $1.16/GB | N/A |
| MP4 video (short clips) | ~50 MB/min | $0.096/GB | $0.58/GB (50K plan) | $0.45–$1.44/GB |
| MP3/WAV audio | ~10 MB/min | $0.48/GB (1-min floor) | $1.16/GB | $0.045/GB (audio rate) |
The key insight: per-minute billing (CloudConvert, AWS MediaConvert) is cheapest for large files and expensive for small files. Flat-rate per-conversion (ChangeThisFile) is cheapest for small files and high-volume batches.
How different billing models translate to per-GB cost
Per-minute billing (CloudConvert, AWS MediaConvert)
Cost per GB depends heavily on the relationship between file size and processing time. A 100 MB video might take 60 seconds to transcode = 1 conversion-minute = $0.0048 (CloudConvert). That's $0.048/GB — reasonable. But a 500 KB DOCX→PDF conversion also takes 20–30 seconds and bills as 1 minute = $0.0048. For that 500 KB file, the effective rate is $9.60/GB — absurdly expensive per unit of data.
Per-conversion flat billing (ChangeThisFile)
Cost per GB is inverse to file size: small files are expensive per GB, large files are cheap per GB. At $0.0029/conversion (ChangeThisFile Hobby: $29/10K), a 500 KB DOCX costs $0.0029 regardless of file size = $5.80/GB. A 50 MB video costs the same $0.0029 = $0.058/GB.
Per-MB/GB data billing (Cloudinary, ImageKit)
These image CDN/transformation APIs often charge by storage + bandwidth + transformation count. Cost per GB of transformations is typically $0.01–$0.05/GB for images when you factor in transformation count billing.
Self-hosted
Marginal cost per GB of conversion: essentially $0 (you're paying for the server regardless). But the fixed cost of $150–$300/month in engineering time divides across your volume. At 100 GB/month processed, that's $1.50–$3.00/GB in hidden engineering cost.
Hidden per-GB costs most teams miss
Egress bandwidth costs. AWS charges $0.09/GB for data transfer out of regions. If you upload a 1 GB video to AWS S3, MediaConvert transcodes it, and you download the output — you pay for 1 GB upload (free into S3), processing time (MediaConvert), plus ~1 GB download ($0.09). For video pipelines running at scale, egress can equal or exceed the conversion cost.
Storage while processing. Managed APIs that store input/output files during processing may charge for temporary storage. CloudConvert uses its own cloud storage and doesn't explicitly charge per-GB for temporary storage, but files count against storage quotas on some enterprise plans. AWS MediaConvert uses S3, and your input/output files accumulate S3 storage costs until you delete them.
Re-conversion without caching. If your app converts the same 50 MB video five times (different users, same source file), you pay five times for the same GB of processing. Cache conversion outputs by input file hash + parameters to eliminate redundant processing.
Failed conversions still consume bandwidth. A 100 MB file that fails mid-conversion has already uploaded. Some APIs don't charge for failed processing time but you've paid egress bandwidth to upload the file.
How to minimize per-GB costs by format type
Images (JPG, PNG, WebP, HEIC)
Best option: client-side conversion. ChangeThisFile processes 161 routes entirely in the browser — zero upload cost, zero processing cost, zero per-GB cost. For API-based image conversion, ChangeThisFile's flat rate is significantly cheaper per GB than CloudConvert's minimum-1-minute billing at small file sizes.
Documents (DOCX, PDF, HTML)
Average DOCX file is 300 KB–2 MB. Per-minute billing is a terrible fit — you pay 1 full minute for a 10-second conversion. Flat-rate per-conversion (ChangeThisFile) or self-hosted LibreOffice are better fits for document-heavy workflows.
Video (MP4, MKV, MOV)
Per-minute billing is best for video because processing time scales proportionally with file size. AWS MediaConvert at $0.0075–$0.024/output-minute is designed for video at scale. CloudConvert handles smaller video batches. For consistent high-volume video (100+ GB/month), self-hosted FFmpeg on a capable VPS is cheapest.
Audio (MP3, WAV, FLAC)
Short audio files (1–5 MB) are similar to images — per-minute billing is expensive per unit. For audio conversion, AWS Elastic Transcoder's audio rate ($0.00417/minute) or ChangeThisFile's flat rate are more cost-effective than CloudConvert for typical audio file sizes.
Industry benchmarks: cost per GB by provider
| Provider | Model | Image (2MB avg) | Document (500KB avg) | Video (50MB/min) | Audio (10MB/min) |
|---|---|---|---|---|---|
| CloudConvert PAYG | Per minute ($0.0048) | $2.40/GB | $9.60/GB | $0.096/GB | $0.48/GB |
| ChangeThisFile Hobby ($29/10K) | Per conversion ($0.0029) | $1.45/GB | $5.80/GB | $0.058/GB | $0.29/GB |
| ChangeThisFile Startup ($99/50K) | Per conversion ($0.00198) | $0.99/GB | $3.96/GB | $0.040/GB | $0.198/GB |
| AWS MediaConvert (SD) | Per output minute | N/A | N/A | $0.45/GB (est.) | $0.025/GB (est.) |
| Self-hosted (VPS only) | Fixed monthly | Near $0 | Near $0 | Near $0 | Near $0 |
| Self-hosted (with eng time) | Fixed + hidden | $1.50–$3/GB* | $1.50–$3/GB* | $0.15–$0.30/GB* | $0.15–$0.30/GB* |
*Self-hosted with eng time assumes $225/month engineering overhead divided by total GB processed that month. Lower per-GB cost as volume increases.
Choosing the right model for your GB profile
You process many small files (images, documents)
→ Flat-rate per-conversion (ChangeThisFile) or client-side conversion wins. Per-minute billing is brutal on small files.
You process a few large files (video, large archives)
→ Per-minute billing or self-hosting wins. Large files spread the per-minute cost across enough data to be reasonable.
You have unpredictable volume
→ Pay-as-you-go (CloudConvert PAYG or ChangeThisFile free tier + overage) is safer than flat-rate plans you might underutilize.
You process 100+ GB/month of the same format type
→ Self-hosting is worth evaluating, especially if the format type is well-supported by a single tool (FFmpeg for video, LibreOffice for documents).
Cost per GB summary table
| Scenario | Best provider | Effective $/GB | Notes |
|---|---|---|---|
| Image conversion, high volume | ChangeThisFile Startup | ~$0.99/GB | Or client-side for free |
| Document conversion, high volume | ChangeThisFile or self-hosted | $1–$4/GB | Per-minute billing very expensive here |
| Video transcoding at scale | AWS MediaConvert or self-hosted | $0.05–$0.45/GB | Per-minute model designed for this |
| Audio conversion at scale | AWS Elastic Transcoder or CTF | $0.025–$0.30/GB | Depends on file size distribution |
| Mixed formats, moderate volume | ChangeThisFile Hobby | $1–$2/GB avg | Simplest pricing for mixed workloads |
Per-GB cost benchmarking reveals a clear pattern: per-minute billing works well for video (where processing time scales with file size) and poorly for documents and images (where small files hit the minimum billing floor). For mixed-format workflows, flat-rate per-conversion pricing offers the most predictable effective cost per GB. ChangeThisFile's free tier lets you test your actual file size distribution against their rates before committing to a plan.