# MicroSD Card Size and Speed Calculator

Work out the card capacity and write speed you need for video recording or a console, and read what the speed marks mean.

- URL: https://toolstackhub.co.uk/tools/microsd-card-size-and-speed-calculator/
- Category: Calculators
- Price: free, no sign-up
- Privacy: runs in the browser; input is not uploaded
- Last updated: 2026-10-08

## About
Choose what you are recording or using the card for, and how long you want to record. The calculator turns the video bitrate into the write speed (MB/s) and the gigabytes you need, with a safety margin, and shows which speed class marks to look for: U1, U3, V30, V60, V90, A1 and A2. It cannot tell you your device's maximum supported capacity or card type, so check the device's manual before buying.

## How to use
1. Enter your values in the fields above.
2. The result updates automatically as you type.
3. Copy or note the figures you need.

## FAQ
**What do U3, V30 and A2 mean?** U3 and V30 both guarantee at least 30 MB/s sustained writing, which suits 4K video. A1 and A2 describe how quickly a card handles small random reads and writes, important for apps and games.

**What size card do I need?** It depends on bitrate and recording time. At 100 Mbps, 4K video fills about 45 GB an hour, so a 128 GB card holds roughly two and a half hours.

**Is the MicroSD Card Size and Speed Calculator free?** Yes, with no sign-up or limits.