Tools

How thin the air is for your engine and wings: pressure altitude, ISA deviation and density altitude.

The crosswind and headwind on a runway from the wind's direction and speed.

True airspeed from calibrated airspeed, pressure altitude and temperature.

Heading to fly and ground speed for a course, given the wind.

Give two, leave one blank, and it solves for the third. Distance in nautical miles, speed in knots.

How far out to start down, and the descent rate to hold it.

Endurance and range from fuel on board, burn rate, speed and a reserve.

Total weight and centre of gravity from what is on board. The starting numbers are an example, so put in your aircraft's own.

Height of the cloud base from the temperature and dew point.

Altimeter and barometer pressure: inches of mercury, hectopascals (millibars), millimetres of mercury and kilopascals. Fill in one.

The FAA's active TFRs, nationwide or for one state, with links to each.

Paste a METAR or TAF and read it in words, with its flight category.

Minimum visibility and cloud clearance by airspace class.

The dew point from temperature and relative humidity, and whether fog or dew is likely.

How hot it feels once humidity is counted (the US National Weather Service formula).

How cold it feels with the wind (the US National Weather Service formula).

How far away a lightning strike is from the seconds between the flash and the thunder.

The Beaufort force for a wind speed, and what the sea looks like.

The speed a displacement hull can not easily pass, from its waterline length.

How much rode to let out: the depth plus the height of your bow above the water, times the scope.

Flight time from the battery's capacity and your average current draw, and the C rating it needs.

Voltage, capacity and energy of a pack built from cells in series and parallel (LiPo, Li-ion, LiFePO4).

The top speed a propeller can pull the model to, from its pitch and the motor's RPM.

No-load RPM of a brushless motor from its KV rating and the battery voltage.

Thrust against weight for a drone or model. Above 1 it can hover; racing quads run 5 to 10.

Signal strength at the receiver over open air, and how far the link reaches, for an FPV video or control link.

How much clear space a radio link needs around the straight line between the antennas.

Dipole and vertical lengths for a frequency.

Radio power in dBm, milliwatts and watts. Fill in dBm or milliwatts.

Volts, amps, ohms and watts: give any two, leave the others blank.

The series resistor for an LED, and the nearest standard value.

Where the space station is right now, and when it passes over a place. Worked out in your browser.

How big a power supply a build needs, from the parts' own power draw.

The true latency of a memory kit in nanoseconds, and its bandwidth: a CAS number means nothing without the speed.

Pixel density, pixel size and physical dimensions of a screen.

Whether a cable and port can carry a resolution and refresh rate, before compression.

Usable space and fault tolerance for RAID 0, 1, 5, 6 and 10.

How long a download, upload or copy takes.

Why a 1 TB drive shows less than 1 TB: drive makers count in powers of ten, operating systems in powers of two.

Compare storage by what a terabyte costs.

What a device costs to run: a PC, a server, a heater, a charger.

How long a battery backup carries a load.

Every button and stick of a connected controller, and drift.

Click speed, double-click faults, polling rate, buttons and wheel.

How much of the picture is sharp: near and far limits and the hyperfocal distance for a lens, aperture and subject distance.

Exposure value (EV) for an aperture, shutter speed and ISO, and the shutter speed that gives the same exposure at other apertures.

How wide a lens sees on a camera sensor: horizontal, vertical and diagonal angle.

Magnification, exit pupil, limiting magnitude and field of view for a telescope and eyepiece.

The value of a four-band resistor from its colours.

The output of two resistors in series, and the current they draw.

Time constant, cutoff frequency and charge times of a resistor and capacitor.

Frequency and duty cycle of a 555 in astable mode.

Diameter and circumference of a tire, and how much a different size makes the speedometer read wrong.

Road speed for an engine speed, tire size and overall gear ratio.

Displacement from bore, stroke and cylinders.

What a drive costs in fuel.

Pace and speed from a distance and a time, and what that pace predicts for other race distances.

Your estimated best single from a set of several repetitions.

Training zones from your age, and your resting heart rate if you know it.

Lumber volume in board feet.

Cubic yards of concrete for a slab, and how many bags of mix.

Cubic yards of mulch, soil or gravel for a bed, and how many bags.

Gallons of paint for a wall or room.

Filament length for a weight, or weight for a length, by material and diameter.

Network, mask, broadcast and hosts for an address and prefix, and how to split it.

Expand or compress an IPv6 address.

What a cron expression means and its next run times.

Tick permissions, get the octal and the command.

MD5, SHA-1, SHA-256, SHA-384, SHA-512 and CRC32 of text or a file, checked in your browser.

Read a token's header, payload and expiry.

Every HTTP status code, filterable.

Well-known TCP and UDP port numbers.

A, AAAA, CNAME, MX, TXT and the rest, with examples.

Try a regular expression against text and see every match.

Format, validate and minify JSON.

URL, Base64 and HTML encoding and decoding.

Compare two texts line by line.

Unix time to a date and back.

Binary, octal, decimal and hexadecimal, and text to binary.

Words, characters, sentences and reading time.

Upper, lower, title, sentence, camel, snake and kebab case.

Placeholder text by the paragraph.

Text to Morse and back, with sound.

Numbers to Roman numerals and back.

Length, mass, volume, area, speed, temperature, time and data.

Read text aloud with your device's voices.

A QR code for any text or link, drawn in your browser.

Pick a colour and copy it as hex, RGB or HSL.

A page to type on, kept in your browser.

A scientific calculator.

Plot functions of x.

Monthly payment and total interest.

Monthly payment on a car loan.

Payment and payoff schedule for any loan.

Growth of savings with regular deposits.

Body mass index in metric or imperial.

Exact age from a birth date.

Percent of, percent change and percent difference.

A tip and the bill split between people.

Days between two dates, or a date plus days.

Any month or year.

Focus and break intervals.

Spin a wheel of names or choices.

A steady beat at any tempo.

Tune a guitar, ukulele, bass or violin with the microphone.

Heads or tails.

Roll one or more dice.

A random number in a range.

A strong password made in your browser.

A random UUID.

See what your camera sees.

Check your microphone and its level.

See every key you press light up.

Left, right and full-range test tones.

Solid colours to find dead or stuck pixels.

Your screen size, browser and device.

A ruler at real size, in inches or centimetres.

Against a computer that does not lose.

The classic.

Three sizes.

Slide and merge tiles.

Find the pairs.

Puzzles, hints, and a solver for one you are stuck on.