Specifications that become useful once the units are separated
These guides focus on questions where a connector name, headline wattage, resolution label, diagonal size, refresh rate, luminance claim, HDR tier, speed class, form factor, endurance rating, lane count, battery designation, or capacity label leaves out something important. Each page explains the underlying measurement, then shows what the number can and cannot tell you.
Displays
Monitor dimensions from diagonal and aspect ratio
Convert a diagonal measurement into approximate active-panel width and height, and see why identical diagonals can produce different shapes.
Aspect ratios16:9 versus 16:10 at the same diagonal
Compare approximate width, height, and panel area for 24, 27, and 32 inch displays instead of assuming a shared diagonal means a shared footprint.
PPIPixel density from resolution and screen size
Calculate pixels per inch and understand why resolution alone does not describe physical pixel size or perceived sharpness.
Resolution4K versus UHD versus 2160p
Separate consumer 3840×2160 4K UHD from the 4096×2160 DCI cinema container, then check what the “4K” label still leaves unspecified.
Refresh rate60Hz, 120Hz, 144Hz and 240Hz in milliseconds
Convert hertz into refresh interval, then keep refresh rate separate from FPS, pixel response time, variable refresh, and the connection carrying the mode.
LuminanceNits versus cd/m²
See why the units are numerically identical, how luminance differs from lux and lumens, and why a peak-brightness claim still needs test context.
HDRDisplayHDR 400, 600, 1000 and True Black
Separate the certification tier's small-area peak from sustained full-screen brightness, black level, color gamut and local-dimming requirements.
Cables, ports, and display links
USB-C cable capabilities
Separate connector shape from data rate, charging power, and display support before treating two USB-C cables as equivalent.
USB-C labelsHow to read 60W, 240W, and data-rate cable markings
Read certified power and performance markings as separate capabilities so a wattage label is not mistaken for a data-speed claim.
USB data ratesUSB 3.0, 3.1, and 3.2 names versus actual speed
Translate Gen 1, Gen 2, and Gen 2x2 into 5, 10, and 20Gbps data classes instead of assuming a newer USB 3.x label always means a faster port.
USB4 & ThunderboltUSB4 versus Thunderbolt 4 and Thunderbolt 5
Separate the shared USB-C connector from USB4 performance levels and Intel's mandatory Thunderbolt 4/5 certification requirements.
USB-C displaysWhy some USB-C ports output video and others do not
Trace monitor compatibility through the host port, DisplayPort Alt Mode or USB4 path, cable, dock, and display instead of trusting connector shape.
HDMIHDMI cable categories and bandwidth
Use official cable categories and certified bandwidth language instead of assuming every “HDMI 2.x cable” listing means the same thing.
DisplayPortDP54, DP80 and UHBR cable labels
Separate DisplayPort version numbers from UHBR link rates and VESA cable classes, including the DP40-to-DP54 change.
Display compressionWhat Display Stream Compression actually does
Understand visually lossless DSC, compression ratios, why the cable is not doing the compression, and what the whole display path must support.
Storage and data rates
TB, TiB, GB, and GiB
Separate decimal drive capacity from binary display units and calculate why 1 TB corresponds to about 931 GiB before formatting overhead.
SSD interfacesM.2 versus NVMe versus SATA
Separate physical form factor from storage protocol and interface so a drive that fits the slot is not assumed to be electrically compatible.
PCI ExpressPCIe 3.0, 4.0 and 5.0 x4 bandwidth
Separate PCIe generation from lane count, convert GT/s into an encoded link ceiling, and see why an SSD benchmark remains lower than the interface maximum.
SSD enduranceTBW versus DWPD
Convert total terabytes written into capacity-normalized daily endurance and see why workload and warranty context still matter.
SSD performanceIOPS versus MB/s
Use block size to connect operations per second with data rate, then keep queue depth, latency, access pattern and interface limits attached to the benchmark.
Transfer ratesMB/s versus Mb/s
Convert bits per second to bytes per second and avoid comparing network-link numbers directly with storage-copy numbers.
Transfer timeEstimate file transfer time from size and sustained rate
Match GB, MB/s, and Mb/s correctly, calculate an ideal lower bound, and see why an interface's headline rate rarely equals sustained file payload.
SD & microSDDecode C10, U3, V30, V60 and SD Express classes
Separate minimum sequential speed classes from UHS/SD Express bus interfaces and from headline “up to” speeds before buying a card for a camera or reader.
Small batteries
CR2025 versus CR2032
Compare nominal voltage, diameter, thickness, and manufacturer guidance before assuming similar-looking lithium coin cells are interchangeable.
Coin-cell sizingCR2016 versus CR2025 versus CR2032
Decode the shared 20 mm diameter, compare the 1.6, 2.5, and 3.2 mm thicknesses, and put manufacturer capacity figures in context.
Coin-cell chemistryCR2032 versus BR2032
See why the same 20 × 3.2 mm size and 3 V rating do not make manganese-dioxide CR and poly-carbonmonofluoride BR cells interchangeable.
Button-cell chemistryLR44 versus SR44
Separate alkaline LR44/A76/AG13 labels from silver-oxide SR44/357 markings, then compare voltage, size and datasheet test conditions before substituting.
AA chemistry1.5V alkaline versus 1.2V NiMH AA batteries
Separate nominal voltage from loaded behavior, capacity test conditions and charging rules before deciding whether a rechargeable AA is appropriate for a device.
Charging, power, and energy
USB-C charger wattage and negotiation
See why a charger's maximum wattage is an offered capability, why the device still matters, and how the cable can become a separate power limit.
USB PD rangesSPR versus EPR: 100W, 140W, 180W and 240W
See how Extended Power Range adds 28V, 36V and 48V operation, and why the charger, device and cable must all support the intended high-power contract.
USB PD PPSWhy PPS is different from charger wattage
Learn how a device requests programmable voltage/current from a PPS range and why two chargers with the same wattage can expose different fast-charging capabilities.
Power & energyWatts versus watt-hours
Separate power rate from energy quantity, then use Wh ÷ W to calculate an idealized time without mistaking it for guaranteed battery runtime.
Battery energymAh versus Wh
Convert charge capacity and rated voltage into watt-hours, and see why the same mAh number can represent different amounts of energy.
How to use this library
Start with the label you are trying to interpret, then keep the page's limits in view. SpecPlain deliberately avoids turning a single specification into a product verdict. A “4K” label can refer to different rasters depending on context and does not prove refresh rate, HDR quality, or link bandwidth. A refresh-rate number can be converted into an ideal frame interval, but it does not by itself prove game FPS, pixel response, total latency, or that the selected resolution can run at that rate. A nit and a cd/m² are the same luminance unit, but a peak claim still needs a test condition. A USB 3.2 label does not identify one single data rate, and a USB-C connector does not prove USB4 or Thunderbolt support. A high charger wattage does not prove PPS support or that a device will charge at that rate. A DisplayHDR tier does not mean the whole screen sustains the tier number indefinitely. DSC compression does not automatically mean chroma subsampling. An SD card's interface, capacity and speed class are separate facts. An M.2 label does not prove whether an SSD uses SATA or NVMe, a PCIe generation label does not tell you the lane count, a TBW rating does not predict an exact failure date, a shared button-cell size does not erase chemistry differences such as LR44 versus SR44, and an AA form factor does not make 1.5 V alkaline and 1.2 V NiMH cells electrically identical.
Calculators on this site run locally in the browser and exist to expose the arithmetic, not to hide it. Standards claims are linked to primary sources where practical. See the editorial policy and sources and methodology pages for the sourcing and correction method.