Simple, useful one-page tools.

🚲 Cycling

Tire pressure

Recommended front/rear PSI based on rider weight, tire width, type, and surface.

Tire & tube compatibility

Compatible inner tubes, ETRTO size, rim width guide, and pressure range for any tire.

Spoke length

Exact spoke lengths from hub flange dimensions, rim ERD, and lacing pattern.

Chain length

Correct number of links for a new chain from chainstay length and gearing.

Torque spec reference

Searchable torque values for stems, BB, brakes, pedals, and more — plus BB shell standards.

Saddle height

Starting saddle height from inseam using LeMond, Hamley 109%, and Lewin methods.

Bike fit basics

Crank arm length and handlebar width recommendations from body measurements.

Gear ratio & speed

Chainring, cog, wheel size, and cadence → gear ratio and riding speed.

Power & speed

Speed from watts, or climbing time from gradient and power — physics-based model.

Training zones

Heart rate zones from max HR, Karvonen method, and Coggan power zones from FTP.

Calories burned cycling

Estimate kcal burned from weight, duration, and intensity (MET-based).

Gear inches chart

Gear inches, gain ratio, or speed for every chainring × cog combination on one chart.

Watts per kilogram

Power-to-weight from FTP and body weight, with rider category benchmarks.

🖥 Computers & Dev

File size & transfer time

Transfer time at any connection speed, plus a storage unit converter.

Aspect ratio & resolution

Find ratio, scale dimensions, or verify a size matches a target ratio.

Color converter

Convert between HEX, RGB, and HSL with a live color preview swatch.

Unix timestamp

Convert epoch timestamps to readable dates — or any date back to Unix time.

Number base converter

Convert between binary, octal, decimal, and hexadecimal — type in any field.

JSON formatter & validator

Pretty-print, minify, and validate JSON with clear error messages.

Base64 encode / decode

Convert text to and from Base64 live, both directions, UTF-8 safe.

URL encoder / decoder

Percent-encode or decode URLs and query strings — component or full URL.

UUID generator

Generate one or many v4 UUIDs with case and hyphen options — copy in a click.

Hash generator

SHA-1, SHA-256, SHA-384, and SHA-512 digests of any text, computed in-browser.

JWT decoder

Decode a JSON Web Token's header and payload locally, with claims humanized.

Regex tester

Test a regular expression against text with live match highlighting and groups.

Password generator

Strong random passwords with length, character-set, and strength controls.

Cron expression explainer

Translate a cron schedule into plain English and preview the next run times.

🌐 Networking

IPv4 subnet calculator

Network, broadcast, host range, mask, wildcard, and class from an IP and CIDR.

CIDR ↔ subnet mask

Convert prefix to mask and back, with a full /0–/32 reference table.

IP address converter

IPv4 between dotted-decimal, integer, hexadecimal, and binary — live, both ways.

IPv6 expand / compress

Expand or canonically compress an IPv6 address (RFC 5952) and find its prefix network.

MAC address formatter

Reformat a MAC across notations, read its U/L and I/G bits, and derive EUI-64.

VLSM subnet splitter

Split a network into equal subnets or allocate by host requirements, VLSM-style.

Wi-Fi channel reference

2.4, 5, and 6 GHz channels, frequencies, DFS, widths, and non-overlapping picks.

🛜 UniFi / Ubiquiti

UniFi PoE budget

Check whether a UniFi PoE switch has enough power and ports for your APs and cameras.

UniFi Protect storage

Size NVR storage and drives from camera bitrates, retention, and recording mode.

📅 Calendar & Time

Date & time tools

Date difference, add/subtract time, age calculator, day of week, countdown, and week numbers — all in one.

Time zone converter

Convert one time across many world time zones at once — DST-aware.

📊 Math & General

Compound interest

Investment growth with monthly contributions — year-by-year table included.

Unit converter

Length, weight, temperature, volume, and speed — pick a category and type.

Percentage calculator

X% of Y, what percent A is of B, percent difference, and apply ±%.

Tip calculator

Tip amount, total, and per-person split with quick preset percentages.

Loan calculator

Monthly payment, total interest, and total cost for any fixed-rate loan.

Debt payoff planner

Compare snowball vs. avalanche payoff time and interest across multiple debts.

🏠 Real Estate

Mortgage calculator

Monthly payment and total cost estimates for fixed-rate loans.

Home affordability

Max home price based on income, debts, and the 28/36 qualifying rule.

Amortization schedule

Month-by-month principal vs. interest breakdown for any fixed-rate loan.

Closing costs estimator

Itemized estimate of typical buyer closing costs — adjustable to match your quote.

Rental yield & cap rate

Gross/net yield, cap rate, and monthly cash flow for investment properties.

Home appreciation

Future home value and equity growth at a given annual appreciation rate.

Rent vs. buy

Compare long-term net worth of renting vs. owning — with break-even year.

🏋️ Health & Fitness

BMI calculator

Body mass index from height and weight, metric or imperial, with category.

TDEE & BMR calculator

Daily calorie needs from the Mifflin–St Jeor equation and your activity level.

One-rep max

Estimate your 1RM from weight and reps, plus a training-percentage table.

🎨 Design & Web

Color contrast checker

WCAG contrast ratio between two colors with AA/AAA pass-fail and a live preview.

CSS px ↔ rem / em

Convert between px, rem, and em at any base font size, with a reference table.

🎬 Media & Video

DVD / Blu-ray bitrate & fit

Max video bitrate that fits a DVD or Blu-ray from runtime and audio — or check whether a bitrate fits.

Video bitrate ↔ file size

Solve file size from bitrate and duration, or the bitrate needed to hit a target size.

Timecode & frames

Convert between SMPTE timecode, frame count, and real time at any frame rate — drop-frame aware.

Streaming data usage

How much data a stream uses by quality and time — or how long a data cap lasts.

Uncompressed video size

Raw data rate and size from resolution, frame rate, bit depth, and chroma subsampling.

Letterbox / pillarbox

Black-bar sizes when fitting one aspect ratio inside another, with a live preview.

Audio file size

File size for compressed or uncompressed PCM/WAV audio from duration and quality.

DVD / Blu-ray region reference

Region codes by country, disc capacities, and NTSC vs. PAL — all in one place.