Bend Bench puts conduit bending marks and everyday electrical numbers on your iPhone: eight bending layouts with diagrams, plus Ohm's law, power, voltage drop and wire size by voltage drop. It works offline and needs no account.
Reference calculations. Check every result against the applicable code, your equipment manufacturer's data and local requirements. The Wire Size calculator looks at voltage drop only, not ampacity. Bend Bench does not replace a licensed electrician.
Write to us
jacob.baker8466@gmail.com
So we can reproduce what you see, please add:
- your iPhone model and iOS version;
- the Bend Bench version (Settings > About > Version);
- the calculator and the values you entered. The quickest way is the Share button on the result or on the saved entry in History: send it to the address above and the email will contain the inputs and results exactly as the app shows them.
First steps
What is the notice on first launch? It explains that the results are reference calculations. Tap I understand to open the calculators. You can read it again at any time in Settings > About > Disclaimer.
How is the app organized? Three tabs at the bottom. Tools lists the calculators in two groups, Bending and Electrical. History holds the calculations you saved. Settings has units, rounding, the voltage drop limit, benders, appearance and haptics.
Where is the Calculate button? There isn't one. Results update as you type and show a dash until enough values are filled in. A red line under a field tells you what needs to change.
Can I copy a result? Tap the value. It goes to the clipboard and you can paste it anywhere.
What do the marks and terms mean? Tap What the marks mean above the diagram, or the info button at the top of a calculator, for a short legend: mark, shrink, take-up, gain, near and far critical, rounding and the other terms that calculator uses.
Entering measurements
The measuring keypad opens when you tap a field.
- Inches with fractions: type the whole inches, then tap the fraction keys. They add up: 6, then 1/4 and 1/8, gives 6-3/8". Tap a fraction key again to remove it.
- Feet and inches: type the feet, tap ft′, then type the inches. 2, ft′, 4, 1/2 gives 2' 4-1/2".
- Decimal inches are accepted too: use the decimal key instead of the fractions.
- Metric lengths are entered in millimeters, with one decimal place if you need it.
- Run length in Voltage Drop and Wire Size is entered in feet (Imperial) or meters (Metric), one way, decimals allowed.
- Angles: pick 10°, 22.5°, 30°, 45° or 60°, or Custom for any angle from 10° to 60°.
- C clears the field, the arrow key deletes the last entry, Next moves to the following field and Done closes the keypad on the last one.
Bending calculators
Offset. Enter the offset height and the angle. You get the distance from mark to mark and the shrink. Add the distance from the pipe end to place both marks from the end: choose Near critical when the first bend must start at that distance, or Far critical when the offset must be finished by that distance (the shrink is then added for you).
Rolling Offset. Enter the rise, the roll and the angle. The app finds the true offset, then gives the mark-to-mark distance, the shrink and how far to rotate the pipe.
3-Point Saddle. Enter the obstruction height. The center bend is 45° over the middle of the obstruction and the two outer bends are 22.5°. You get the distance from the center mark to each outer mark and two shrink values: to the center and in total. Add the distance to the center of the obstruction to get all three marks from the pipe end.
4-Point Saddle. Enter the obstruction height and width and the angle. You get marks 2, 3 and 4 measured from mark 1 and the total shrink.
90° Stub-Up. Enter the stub height. The mark from the pipe end is the stub height minus the take-up of the selected bender. Add a second leg length to get the cut length. Gain and the cut length need the center-line radius of the bender and show n/a without it.
Kick. Enter the kick height and the angle to get the path along the pipe to the surface, the run along the axis and the shrink.
Back-to-Back 90. Enter the first stub height and the distance between the backs of the two 90s. You get the first mark (stub height minus take-up) and the second mark, measured from the back of the first 90. Line up the second mark with the back-of-90 mark on your bender.
Parallel Offsets. Enter the number of conduits (2 to 6), the center-to-center spacing and the angle. The app gives how far each conduit's marks shift, with a table per conduit. Conduit 1 is the inner pipe of the offset. Add the offset height to see the full marks as well.
My marks don't match my bender
- Take-up. The built-in presets (EMT 1/2", 3/4", 1" and 1-1/4") use typical take-up values. Benders differ, so check yours: open Settings > Benders, pick a built-in preset, tap Duplicate & edit, enter your bender's take-up and select the new preset. You can also create one from scratch with New bender.
- Gain needs the center-line radius of your bender. Built-in presets leave it empty, so gain shows n/a until you add the radius to your own preset.
- Shrink follows the multipliers commonly used in the field for 10°, 22.5°, 30°, 45° and 60°. For a custom angle it is calculated directly from the angle.
- Rounding. In Imperial every mark is rounded on its own to 1/16" or 1/8" (Settings > Rounding); rounded values are never added together. Metric marks are rounded to whole millimeters.
Electrical calculators
Ohm's Law. Enter any two of voltage, current, resistance and power to get the other two. Typing a third value replaces the one you entered first.
Power. Choose DC, AC single phase or AC three phase, then give the current or the power in kW. Power factor starts at 1.00. Add an efficiency to see horsepower at the shaft.
Voltage Drop. Choose the circuit, enter voltage, current and one-way length, pick the wire size and copper or aluminum. You get the drop in percent and volts, the voltage at the end and whether it is within your limit. The calculation uses conductor resistance only, at about 75 °C; reactance is not included, so results for large conductors on AC are approximate.
Wire Size. Same inputs without the wire size. The app gives the smallest size in the list that stays within your voltage drop limit, its drop, and the drop with one size smaller. It does not check ampacity, the current a wire can safely carry; check that separately.
What is the voltage drop limit? The share of the supply voltage you accept to lose along the run. Set the default in Settings (3%, 5% or a custom value from 0.5% to 10%) and change it on the calculator screen for a single calculation.
Why is there an error instead of a result? If the drop would be larger than the supply voltage, the app shows an error rather than a negative voltage. Check the values or pick a larger wire.
Units
Imperial or Metric? The first launch picks Imperial (inches, AWG and kcmil) in the United States and Canada and Metric (millimeters, mm²) elsewhere. Change it in Settings > Units; every calculator switches right away.
Which wire sizes are listed? Imperial: 18 AWG to 4/0 AWG, then 250 to 1000 kcmil. Metric: 1.5 mm² to 300 mm².
History
- Save stores the result with an optional label, for example "Panel 3 A".
- In History, pinned entries stay at the top. Swipe right to pin, swipe left to delete (an Undo button appears for a moment).
- Open an entry to see the inputs, results and diagram, then Use again, Share, rename, pin or delete it. Use again loads the values back into the calculator and switches units if the entry was saved in the other system.
- Up to 200 unpinned entries are kept; past that, the oldest unpinned one is removed. Pinned entries are never removed automatically.
Data and privacy
Everything stays on your iPhone: settings, saved calculations and your bender presets. Bend Bench has no account, does not connect to the internet and contains no analytics or tracking. Deleting the app removes its data. Details: Privacy Policy.
Languages
The app follows your iPhone language: English, German, French, Spanish, Portuguese (Brazil) or Russian. Bending names and trade terms (Offset, Saddle, Kick, Stub-Up, Take-up, Shrink, Gain, Near and Far critical) stay in English in every language, the way they are used on site. To run only Bend Bench in another language, open the iPhone Settings app, find Bend Bench (under Apps on recent iOS versions) and choose Language.
Requirements
iPhone with iOS 17 or later. The app runs in portrait orientation and works without a network connection.
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© 2026 Christopher Thomas