Memory card capacity calculator
Bitrate in, minutes out. Plus the speed rating that decides whether the card can actually keep up.
Researched from published specifications and verified owner reviews · updated 2026
The short answer
Recording minutes equal card capacity in gigabytes multiplied by 8,000, divided by bitrate in megabits per second, divided by 60. At 150 Mbps a 256 GB card holds roughly 3 hours 45 minutes of 4K, and at 300 Mbps it holds about 1 hour 50 minutes. Drone video cards need a V30 rating as an absolute minimum.
Running out of card is a stupid way to lose a shot, and it happens more often than running out of battery because pilots buy the card once and then never think about it again. The arithmetic is simple, the speed rating is the part people get wrong, and the two combine into a rule you can apply to any aircraft: size the card for the whole day, and buy the write speed the highest bitrate mode demands.
SanDisk
SanDisk Extreme PRO 256 GB microSDXC (U3, V30)
U3, V30, 256 GB
V30 is the class mark that guarantees a 30 MB per second sustained write, which is the number that decides whether a high-bitrate clip records or stops, and 256 GB covers a full day of 4K work.
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Storage
Recording time and cards needed
Switch between video and mapping stills. Video is bitrate driven, mapping is image count driven, and the two size a card very differently.
Estimates only, from published specifications. Wind, temperature, altitude, payload and pack age all move the real number, usually in the direction that costs you flight time. Always keep a reserve and follow the manufacturer's own limits.
The formula
Recording minutes equal card gigabytes multiplied by 8,000, divided by bitrate in megabits per second, divided by sixty. The 8,000 converts gigabytes to megabits, since there are 8,000 megabits in a gigabyte for this purpose. Usable capacity is about 93 percent of the advertised figure once the file system takes its share, which the calculator already accounts for.
Bitrate, not resolution, is what fills a card. A 4K clip at 100 Mbps and a 1080p clip at 100 Mbps consume identical space. That matters because the high-quality modes on modern drone cameras run two to three times the bitrate of the standard ones, so switching from 4K 30 to a high-bitrate 5.1K mode can triple your storage requirement without changing anything you would notice on the controller screen.
Recording time by card size and bitrate
| Bitrate | 64 GB | 128 GB | 256 GB | 512 GB | 1 TB |
|---|---|---|---|---|---|
| 60 Mbps (1080p) | 2 h 20 | 4 h 44 | 9 h 28 | 18 h 56 | 37 h 55 |
| 100 Mbps (4K 30) | 1 h 24 | 2 h 50 | 5 h 41 | 11 h 22 | 22 h 45 |
| 150 Mbps (4K 60) | 56 min | 1 h 53 | 3 h 47 | 7 h 35 | 15 h 10 |
| 200 Mbps (4K 120) | 42 min | 1 h 25 | 2 h 50 | 5 h 41 | 11 h 22 |
| 300 Mbps (5.1K) | 28 min | 57 min | 1 h 53 | 3 h 47 | 7 h 35 |
| 900 Mbps (ProRes class) | 9 min | 19 min | 38 min | 1 h 16 | 2 h 32 |
The bottom row is the one that surprises people. A high-end aircraft recording an intermediate codec eats a 256 GB card in under 40 minutes, which is less than two flights. If you shoot that way you carry cards the way FPV pilots carry batteries. The full grid including mapping still counts is on the video bitrate and storage chart.
Speed rating is the part that actually fails
A card that is too small stops recording at a predictable moment. A card that is too slow stops recording at random, seconds into a clip, and that is a far worse failure because you often do not notice until you are home.
The rating that matters is the V class, which guarantees a minimum sustained sequential write: V30 means 30 MB/s, V60 means 60, V90 means 90. Divide your bitrate by eight to get the megabytes per second the aircraft is trying to write, and buy a class comfortably above it. Every consumer drone video mode fits inside V30. The older U3 rating is the same 30 MB/s guarantee expressed differently, so U3 and V30 are interchangeable in practice.
Ignore the big number on the front of the package. That is usually a peak read speed under ideal conditions and tells you nothing about whether the card can sustain a write for twelve minutes straight. A SanDisk Extreme PRO 256 GB microSDXC (U3, V30) ($72) and a Lexar 256 GB microSDXC UHS-I ($58) both carry the rating that matters, and buying from a seller that is not a marketplace reseller is the most reliable defence against counterfeits, which are genuinely common in this category.
How many cards to carry
For video, two or three smaller cards beat one large one. A card failure then costs part of a day instead of all of it, and the marginal cost of a spare is trivial against the cost of a re-shoot. Label them, and get into the habit of swapping at a natural break rather than mid-sequence.
For mapping the answer inverts. A card swap in the middle of a mission means either re-flying lines or reconciling two image sets in processing, and both are worse than buying a larger card. One SanDisk Extreme 512 GB microSD ($140) covers a full survey day with margin. Work out the image count first with the mapping mission planner.
Offload before you drive home
The cheapest insurance in the entire kit is a copy. A SanDisk 1 TB portable SSD (USB-C) ($166) and a USB-C dual-slot SD and microSD card reader ($13) in the glovebox mean the day exists in two places before you leave the site, and reading the card directly is both faster and safer than pulling files off the aircraft over its own cable while the aircraft battery drains.
Then format in the aircraft rather than on the computer at the start of the next session. Formatting in-camera writes the file structure the aircraft expects and clears the fragmentation that quietly degrades sustained write performance over a season of deleting individual files. The full comparison of offload and archive options is at storage for drone footage, and cards themselves at best microSD cards for drones.
Card capacity and battery count are the two ways a shoot runs out of something. Plan the other one with the battery count calculator, and see what goes in the bag alongside both in the drone pilot field kit.
Questions people ask
+ How much footage fits on a 256 GB card?
At 150 Mbps, which is the common 4K setting on consumer camera drones, a 256 GB card holds roughly 3 hours and 45 minutes of continuous recording. At 4K 120 fps or a high-bitrate 5.1K mode running around 300 Mbps, the same card holds under 2 hours. Since a single flight is 20 to 30 minutes and you never record continuously, one 256 GB card comfortably covers a full day of video work.
+ What speed rating does a drone card need?
Look for V30 as a minimum, which guarantees a sustained write of 30 MB per second, or 240 Mbps. That covers every consumer drone video mode. For 300 Mbps and above, or for burst stills on a high-resolution sensor, V60 or V90 gives headroom. UHS speed class U3 is the older equivalent of V30 and is the same guarantee expressed differently.
+ Why did my drone stop recording mid-flight?
Almost always a sustained write failure rather than a full card. Cheap cards and counterfeits advertise a peak read speed and cannot hold their write speed once the internal cache fills, so recording stops seconds into a high-bitrate clip. Buy from a reputable seller, check the V rating rather than the headline megabytes per second, and format the card in the aircraft before every session.
+ Should I use one big card or several small ones?
Several, for video. Splitting a shoot across two or three cards means a card failure costs part of a day rather than all of it, and the marginal cost of a second card is low. For mapping the answer inverts: a single large card avoids a swap mid-mission, and swapping cards between flight lines is how survey days get re-flown.
+ How much space do mapping stills take?
A 20 MP JPEG from a drone camera runs roughly 8 to 11 MB, and the matching raw DNG runs roughly 20 to 25 MB, so a JPEG plus raw pair is around 30 MB. A 1,000 image mission is therefore about 9 GB shooting JPEG only or 30 GB shooting both. Shooting both is the safer default because a raw file rescues an exposure error that would otherwise cost a re-flight.
+ Do I need to format the card every time?
Format in the aircraft, not on a computer, at the start of every shoot and after every offload. Formatting in the camera writes the file system the aircraft expects and clears fragmentation that slows sustained writes. Deleting files individually leaves fragmentation behind and is one of the quieter causes of a dropped recording on an otherwise healthy card.
