Why is it expensive to send pictures with MMS using Messages app on my iPhone?

Sendiung a picture message is expensive with the MMS technology using Messages app on your iPhone, because a picture has much more data than a text message. For exmple, the average size of a picture is about 2,000,000 bytes, while a text message is only 160 bytes. So your wireless carrier charges you more for sending a picture message, because it needs to use more resources.

Here is the price list from an Australia wireless carrier as an example:

Price              Message Type
-----              ------------
25c per message    Text messages (SMS) in Australia
50c per message    Text messages (SMS) to an international number

50c per message    Picture messages (MMS) in Australia
75c per message    Picture messages (MMS) to an international number

75c per message    Video messages (MMS) in Australia

So if your wireless plan does not include unlimited international MMS messaging, you should avoid using the MMS technology. When you need to share pictures with your friend, try the following alternative options:

• Connect to the Internet with Fi-Wi, and use iMessage, Facebook Messenger, Whatsapp messenger or other messenger apps to send pictures. There is no charge from wireless carrier.
• Connect to the Internet with Fi-Wi, and use emails to send pictures. There is no charge from wireless carrier.
• Connect to the Internet with Cellular Data, and use iMessage, Facebook Messenger, Whatsapp messenger or other messenger apps to send pictures. Cellular Data is much cheaper than MMS messages.
• Connect to the Internet with Cellular Data, and use emails to send pictures. or other messenger apps to send pictures. Cellular Data is much cheaper than MMS messages.

⇒ What Is SMS (Short Messaging Service)

⇐ Turn On/Off MMS Function on iPhone

⇑ Using Messages App on iPhone

⇑⇑ Apple iPhone - Frequently Asked Questions