Technology
Built for the case where you need the number in the middle of something else, so every tool here works from a URL you can bookmark and returns a result you can copy in one action. Base-2 and base-10 units are distinguished properly, which is more than most converters manage.
Data
Data Unit ConverterData sizes with base-2 and base-10 units kept properly distinct. A "gigabyte" on a disk label and a "GB" in your operating system are not the same number, and the 7% gap is why a 1 TB drive shows as 931 GB.Data Transfer Time CalculatorHow long a file takes to move over a link, with the bits-to-bytes conversion made explicit and a realistic efficiency rather than the rated speed. A 100 Mbps link does not move 100 MB a second, it moves about 12.5 at best.Streaming Data Usage CalculatorMonthly data usage from streaming habits, and how much of it the video quality setting is responsible for. Dropping one step from 4K to Full HD cuts video usage by more than a third, which is usually the difference between clearing a cap and not.
Networking
Bandwidth Requirement CalculatorLink sizing from user count and per-user demand, separating concurrency from peak. Sizing to the average is the standard mistake: a link that carries the average comfortably is saturated at the busiest hour, which is the only hour anybody notices.IP Subnet CalculatorIPv4 subnet arithmetic, network, broadcast, mask and usable range. Handles the /31 and /32 special cases, which most subnet calculators get wrong.MAC Address FormatterMAC address reformatting between the four common notations. The first three bytes are the manufacturer identifier, and the second-least-significant bit of the first byte says whether the address is globally unique or locally assigned.
Cloud
Cloud Cost CalculatorCloud bill broken into compute, storage, egress and managed services. Egress is the line that surprises people: data going in is usually free and data coming out is not, which is what makes leaving expensive.VM and EC2 Cost ComparisonInstance pricing across on demand, reserved and spot. A reservation is billed whether the instance runs or not, so below roughly sixty percent utilisation on demand is cheaper despite the higher rate.Object Storage Cost CalculatorObject storage cost across tiers, with the retrieval charge included. A colder tier is only cheaper if you rarely read the data, and the break-even retrieval volume is the number that decides it.Data Egress Cost CalculatorEgress cost with tiered rates and CDN offload. Egress is the cost that makes cloud migration expensive: moving 100 TB out is a real bill, and that asymmetry is worth understanding before it becomes a constraint.Kubernetes Resource CalculatorCluster node count from pod resource requests. Nodes are sized on whichever of CPU and memory runs out first, so a workload with a request ratio that does not match the instance type wastes the other resource entirely.
AI & LLM
LLM Token Cost CalculatorModel API cost from token volumes. Output tokens usually price three to five times input, so a small share of the tokens drives most of the bill, and shortening responses saves more than shortening prompts.LLM Context Window CalculatorHow much conversation fits in a context window after overhead. Retrieved documents and the system prompt consume the window before any conversation starts, and reserving space for the response is required rather than optional.AI API Cost Comparison CalculatorModel cost comparison with retries counted. A cheaper model that needs a second attempt on a fifth of requests is not a fifth cheaper, and the break-even retry rate is what decides the choice.Fine-Tuning Cost CalculatorFine-tuning cost and whether it pays back. Tuning usually pays through shorter prompts rather than better output, and where the tuned model prices above the base one that premium can exceed the saving.GPU Training Cost and Time CalculatorGPU training cost with scaling efficiency and failed runs counted. Doubling GPUs does not halve training time, so the cost per useful hour rises with cluster size.Embedding Storage Cost CalculatorVector storage and embedding cost. Storage is vectors times dimensions times bytes, and quantising from float32 to int8 cuts it by four with a small accuracy cost that is usually worth taking at scale.
Developer
Unix Timestamp ConverterUnix timestamp to a readable UTC date. Timestamps deliberately ignore leap seconds, which is why they are simple to compute with and slightly wrong as a count of elapsed time.ISO 8601 Date ConverterISO 8601 formatting in UTC and with an offset, plus the week and ordinal forms. Ordering fields largest first is why ISO strings sort chronologically as plain text.JSON Formatter and ValidatorJSON formatting, minification and validation. Formatting requires parsing, so a document that formats is valid, and one that does not tells you where it broke.Base64 Encoder and DecoderBase64 encoding and decoding, including the URL-safe variant. Base64 is an encoding, not encryption: anyone can decode it, so it hides nothing.URL Encoder and DecoderURL encoding and decoding, with the component and whole-URI variants separated. Encoding a whole URL with the component function breaks it, because that function escapes the slashes and colons that make it a URL.Hash GeneratorNon-cryptographic hashes for checksums and hash tables. These are deliberately not cryptographic: they are fast and easy to find collisions for, so they must never be used for passwords or signatures.
Design
Screen Size CalculatorActual width, height and area from a screen diagonal. Two screens with the same diagonal in different aspect ratios have noticeably different areas, which is what the diagonal convention hides.Font Size and Modular Scale CalculatorA modular type scale from a base size and ratio. Sizes multiply rather than add, which is why the jumps look even to the eye despite growing in absolute terms.CSS Unit ConverterCSS unit conversion between px, rem, em, pt and percent. The difference that matters is that rem is relative to the root and em to the parent, so nested em compounds and rem does not.Grid Layout CalculatorColumn widths for a layout grid, and the width of a span. A span of four columns is wider than four column widths, because it swallows the gutters between them.
Security
Storage
RAID Capacity CalculatorUsable capacity, fault tolerance and rebuild time for the common RAID levels, in both the base-10 units the disks are sold in and the base-2 units the operating system reports. Rebuild time is the figure that decides whether single parity is still reasonable at modern disk sizes.Backup Window CalculatorWhether a backup fits its window, for both the daily incremental and the periodic full. The full is the one that overruns, and it overruns on the night nobody is watching.
More
Video Bitrate CalculatorTarget bitrate for a video encode, from resolution, frame rate, codec and how much motion the content carries. Motion matters as much as resolution: a static talking head at 1080p needs less than half what sport at the same resolution does.Database Sizing CalculatorStorage for a table and its indexes, projected forward at a growth rate. Indexes are the part people leave out of the estimate, and on a narrow table with several of them they can exceed the data.Battery Life CalculatorBattery runtime and cycle life. Nameplate capacity is never fully available: fifteen percent or so is lost to cutoff voltage, ageing and the Peukert effect at higher discharge rates.Crypto Mining Profitability CalculatorMining revenue against electricity and hardware. Every input except your own hashrate moves against you over time: network hashrate rises, rewards halve, and hardware obsoletes.Blockchain Gas Fee CalculatorTransaction fee from gas units and gas price. Gas units depend on what the transaction does and barely change; the gas price is what swings, which is why waiting for a quiet period works.