What is Haikan Pipit?

Haikan Pipit is a free app that lets you quickly and easily calculate pipe cutting lengths based on fitting combinations.

If you struggle with center-to-center measurements in piping work or find dimension calculations to be a hassle, this app is for you. It also supports calculations for 45° fittings, such as DV 45° elbows and 45° Y-fittings that change the flow direction by 45 degrees.

Includes an easy-to-understand pipe catalog with 3D models.
You can intuitively understand the shapes and dimensions of pipes and fittings.

Are you doing this too?

Temporarily assembling fittings and measuring with a tape measure.

But… fittings can shift, and in tight spaces it’s a real pain.
Plus, let’s be honest — it just doesn’t feel that accurate.

In some cases, it’s hard to measure accurately alone, so you often see two or three people working together just to get it done.It’s actually a pretty tough task, isn’t it?ß

You can calculate cut lengths using approval drawings.

Many pipes and fittings follow standardized dimensions based on JIS or other official standards.
That means you don’t need to assemble the fittings in advance — if you measure from an existing pipe, you can calculate the necessary dimensions.

Like this: just measure from the end or center of the pipe.
So, you simply add or subtract the difference between the point you measured and the point you actually need.

For example, in the case of a DV elbow, the dimensions are predefined as shown below.
You can simply add or subtract the difference between the point you measured and the point you actually want to calculate.
The values of L and Z vary depending on the pipe size — for a 50A pipe, L = 58mm and Z = 33mm.

The distance between two center points (②) is commonly called “center-to-center”,
and the act of subtracting Z from the center-to-center distance is called “center offset calculation” (芯引き(Shin-biki) in Japanese).
For calculations involving points ① and ③, the outer diameter of the pipe is also required.
Experienced plumbers often memorize these values for the fittings and straight pipes they regularly use and calculate the cut length manually on the spot.

That’s exactly why Haikan Pipit exists

With Haikan Pipit, all you have to do is select the type of fitting, the nominal size, and the measurement points (such as inside/outside of the pipe, pipe center, or fitting end) — then enter your measurement.
And just like that, you’ll get the correct cut length.

Let’s take a quick look at how it works in practice.
For a full explanation of the basic features, check out the page below — it walks you through everything clearly.

It’s simple:
Just choose the fittings and pipe size, then select the points you’re measuring between.

Use a tape measure to check the actual distance between the specified points.
Then, enter the measured value into the app.

The calculated cut length will be displayed — cut the pipe to that length.
Simple, right?

And There’s More…

That’s exactly the kind of tricky calculation this app was made for!

You can use the same basic steps even for 45° fittings.
In the case of 45° fittings, you can choose between:

• Horizontal Mode: calculates using center-to-center distances (like elbows)
• 45° Mode: calculates the cut length as the hypotenuse based on horizontal distance.

When using reducer (transition) fittings, a red icon will appear.
Tap the red icon to switch the fitting’s connection direction.

Upcoming Features

We’re actively developing the following features, and they will be released in future updates:

• Expanded customization for existing features like containers
• More types of fittings, including water supply core fittings and MD fittings
• Additional DV fittings such as 30° elbows based on manufacturer specs
• The ability to share calculations via QR codes, and support for estimating materials and generating purchase orders

Stay tuned!