MMS Payload & Carrier Limit Calculator
Calculates total MMS media payload size (KB/MB), text character budgets, and checks carrier gateway limits (300KB–1.2MB).
1. Message & Media Payload
Media Attachment
MIME & Gateway Overhead
2. Payload Budget & Gateway Check
50 KB headroom remaining under universal 300 KB gateway ceiling.
Carrier Compatibility Matrix
| Carrier / Network | Gateway Ceiling | Headroom | Status |
|---|---|---|---|
| Universal Safe Baseline | 300 KB | 49.9 KB free | Pass |
| Legacy Gateways & MVNOs | 200 KB | 50.1 KB over | Reject / Compress |
Optimization Recommendations
- Keep under 300 KB: While Verizon and AT&T support 1 MB, Tier-2 carriers and MVNOs (Mint, Cricket, TracFone) compress or drop payloads over 300 KB.
- Optimal Dimensions: For marketing images, use 640×1138 px (9:16 vertical) or 600×600 px at 80% JPEG quality.
About this tool
How to use it
- Enter or paste your promotional or transactional text message into the body editor.
- Choose your media attachment type (JPEG, PNG, animated GIF, MP4 video, audio, or vCard) and specify its file size in KB.
- Alternatively, drop any local image or media file directly onto the upload box to measure its exact client-side byte footprint.
- Select your target gateway profile (Universal Safe 300 KB, Verizon, AT&T, T-Mobile, or Twilio).
- Review the Carrier Compatibility Matrix to ensure your payload delivers without carrier drop or fuzzy re-compression.
Why it matters
Mobile carriers enforce strict file size ceilings on Multimedia Messaging Service (MMS) gateways. If an image or video exceeds a carrier's threshold (often 300 KB for cross-carrier delivery and MVNOs like Mint or Cricket), the carrier either silently drops the message or severely re-compresses the image into an illegible, blurry artifact. Pre-flight payload testing guarantees crisp customer presentation.
When to use it
Consult before launching commercial SMS/MMS marketing blasts, designing rich customer notification workflows, or configuring automated Twilio/Sinch messaging bots.
Good to know
Base64 MIME encoding and standard multi-part boundary headers add between 5 KB and 15 KB of invisible protocol overhead to every media message.
Common questions
What is the safest MMS size for all US carriers?
300 KB (approx. 307,200 bytes) is the industry standard universal limit. While AT&T and Verizon support up to 1 MB, smaller Tier-2 carriers and MVNOs frequently drop messages exceeding 300 KB.
Why did my high-resolution photo look blurry when received on a customer's phone?
When an MMS payload exceeds a receiving carrier's gateway limit, carrier transcoders automatically downscale and re-compress the image down to 80-120 KB, causing severe compression banding and blurriness.
What image dimensions are recommended for MMS marketing campaigns?
640 x 1138 pixels (9:16 vertical ratio) or 600 x 600 pixels (1:1 square) at 75-80% JPEG quality deliver crisp full-screen mobile rendering while remaining under 250 KB.
Are my media files uploaded to any server?
No. All file measurement and character counting executes 100% locally in your web browser using HTML5 File APIs. Zero images or text messages are ever transmitted to any remote servers.