Mobile Engineering Tools
Push Notification Payload Calculator
Enter notification content and custom data to compute payload size and validate against APNs 4KB and FCM 4KB limits.
No data is transmitted — everything runs locallyTool
Example — A short APNs notification with light custom data to confirm safe payload headroom.
Payload size
135 bytes
of 4096 byte limit
Status
✓ Within limit
APNs
Remaining
3961 bytes
available for custom data
Recommendation
Good headroom
About this tool
Push Notification Payload Calculator
The Push Notification Payload Calculator computes total payload size and validates against APNs and FCM limits with title/body truncation warnings.
• Verify push payload fits within APNs 4KB limit before sending
• Calculate payload size for a rich notification with custom data
• Check title and body length for truncation on lock screen
• Validate FCM data message payload before implementing
Affiliate disclosure
Uptime, incident, and on-call management. Better Stack provides status pages, incident management, and on-call scheduling for engineering teams.
View notification delivery with Better Stack
External site · Independent provider · We may receive a commission · Not a recommendation
FAQ
What does this tool tell you?
The Push Notification Payload Calculator computes total payload size and validates against APNs and FCM limits with title/body truncation warnings.
What affects the result most?
APNs payload limit: 4KB for iOS — exceeding silently drops notification. FCM data message limit: 4KB — same constraint. Notification title + body: keep under 65 chars title, 240 chars body for no-truncation display.
How should I use the result?
The calculation is deterministic — the same inputs always produce the same output — so the most useful workflow is to vary one input at a time and see which factor moves the result most. That tells you where to focus your attention before committing to a decision.