Inground Pool Liner Measuring

Pool Liner Measuring Help


The replacement liner installer and liner manufacturer share common goals in providing liners that conform to safety guidelines, that look good, and last a long time. Safety concerns are dealt with separately. In the following pages we will attempt to throw some light on how to measure for liners. Accuracy is the key. Precise measurements are a must. Assumptions have no place in this endeavor. DO NOT attempt to make allowances for stretch or shrinkage no matter what the season. That is the manufacturers job.

Things to Watch For

  • If you have the manufacturers specifications, do not take these as necessarily being the correct dig dimensions for the pool. Often installers will change these dimensions before or during the dig.

  • A dished out or "bowl" shaped hopper. If there are no break lines, you should measure the depth, wall height, and true lengths along the bottom of the pool for the length and width of the hopper. Also, any other dimensions you can supply are always helpful, i.e., depths at given intervals, descriptions, etc.

  • Finished wall height varies. If it does, by an inch or more, especially in the shallow end, make note of it if it cannot be leveled.

  • Be sure to check the shallow end depth at the end wall and at the transition break line. Often the shallow end will have a slight slope to it.

  • Check the slope of the walls, especially on rectangles. Measure width and length of the pool at the top and bottom of the wall. If the difference at the top and bottom is more than 4 inches, let us know.

  • The shallow end may have a cove at the base of the wall. If so, indicate height of the cove and distance into the floor. Give the wall height to the top of the cove AND the shallow end depth to the floor.

  • If there is a safety ledge, give the slope measurements to the edge of the ledge. Again, do not assume, measure all ledges.

Terms and Definitions

A - Overall Length

B - Overall Width

C - Deep End Depth

D - Shallow End Depth/Wall Height

E - Length of Shallow

F - Length of Slope

G - Length of Hopper Pad

H - Length of Deep End Slope

I - Side Slope

J - Hopper Pad Width

K - Side Slope

Finished Depth: The depth of the deep end and of the shallow end with a sand or vermiculite bottom, level and ready for a liner, or the depth to an existing liner from the bead or bead receiver to the pool floor.

Bead: Thick, usually wedge shaped strip on the top of the wall to hold the liner in the receiver. Usually it is a good idea to send us a sample of the bead if it is rounded or hook shaped or if you are not sure if it is standard bead. There are many different types of bead.

Bead Receiver: Small opening all around the pool beneath the coping into which the bead snaps. All depth measurements are taken from here.

True Length: This is not the length of the pool. This is the length of a slope or the bottom of a pool down one slope across the bottom and up the other slope. In other words, from the bottom of one wall to the bottom of the opposite wall keeping your tape measure on the ground. Do not give this measurement except with a bowl shaped hopper or if we request it.

Break Line (Break Point): Any place on the floor of the pool where the angle changes.

Coping: The "cap" at the top of the wall at deck level, usually extending past the plane of the wall and into the pool.

General Measurements

Depth and Slope

First we will cover the basics of measuring depths and slopes. When measuring any slope, the measurement is of the horizontal distance of the slope, NOT the actual length of the slope on the pool floor. When measuring the side and back (end) slopes of any pool DO NOT ASSUME that any of the slopes are the same. Even if they look the same, measure them all. Be sure to double check that your dimensions along the length of the pool equal the actual length and that your width dimensions equal the width.

To measure the slopes of an empty pool, simply hold a measuring stick or tape measure horizontal from the top of the slope, and drop a plumb bob from the ruler to where the slope meets the hopper pad and record this measurement.

To measure the slopes of a full pool, take a long pole and feel where the slope meets the hopper pad or where the long slope meets the shallow end. At that point, bring the pole to the coping at a 90 degree angle and make a chalk mark. This should be done for all break points first, both length and width then measure the distance between the marks. For the first mark from the edge of the pool, measure from the inside of the wall, not from the coping.

To measure the depth of an empty pool, hold a measuring pole vertical from the corner of the hopper pad and run a string across the top of the pool. Record this height. Now subtract the distance from the top of the coping to the bead receiver. Do not measure from the center of the pad as it may be deeper and consequently cause wrinkles.

To measure the depth of a full pool, hold a measuring stick vertical at the corner of the pad and note the depth of the water, then measure the distance from the water line to the bead receiver. Add these to get the finished depth.


When measuring the length and width of a pool, measure inside the pool from wall to wall below the coping.

NOTE: On symmetric pools (with no left or right bend) if you are requested to measure both walls, all four corners, measure diagonals, or several wall heights, please do, although they need not be recorded unless there is a difference in any of them that might affect liner fit.

Other Types of Pools

Roman Ends

Measure like a rectangle but indicate how far the bow(s) extend past the end of the pool. Also indicate the shape of the hopper pad, square or rounded on one end, if rounded, give the length of the straight side of the hopper pad (see "R3" dimension in oval section). If the hopper is square, the slope may not extend into the bow. Indicate if the bow area is flat. Give the overall length of the pool AND the long wall length. Finally, measure from the corner of the pool to where the bow begins or the width of the bow.

Straight Slopes

These are measured similar to a rectangle. Since there are no side slopes, no back slope, and often no shallow end or flat section in the deep end you need to take only a few measurements. If there are break lines in the deep or shallow ends, we obviously need them. The depth should be taken at all break lines and at least once in the middle of the slope.


The only difference here is the lack of a hopper pad. Measure all slopes and depths as you would a rectangle.


Measure the deep just like a rectangle. Measure the length of all the walls. Indicate the direction of the "L" standing at the deep end. Check the INSIDE corner. Indicate whether it is square or otherwise. Include a SKETCH.


Measure the same as you would a rectangle. You will need to measure the width in the center as well as both ends, and measure all walls. Do not assume they are the same. Occasionally they are not. Note pad shape.

Flat Bottoms

All flat bottoms are measured the same as their hopper counterparts. Measure the depth at the wall AND in the middle. Sometimes flat bottoms aren't truly flat. Take as many diagonal measurements at the top and bottom of the wall as you think necessary, especially if the pool looks obviously out of square.

Vinyl Covered Steps

  • Measure all risers; R1, R2, R3, R4 (R5 if it is a 4-tread step). The risers should equal the Shallow end depth.

  • Measure all treads; T1, T2, T3 (T4 if a 4-tread step).

  • Measure the total width of the step across the inside.

  • Measure the width of the treads from the back wall of the step to the pool wall.

  • Indicate if the bottom step is set back from the pool wall. If so, measure the distance.

  • Give the type of corner at the back and front of the step.

  • Give the location of the step. If it is not at the center of the shallow end or flush against a corner, then give the distance from the closest corner.

  • Note whether the step needs pockets for rods or tabs for nailing.

Kidney & Free Form Pools (A-B Method)

  1. Select 2 points outside the pool on a long side at least 3 feet from the pool and approximately 2/3 the length of the pool apart and RECORD THAT DISTANCE. These are your A & B points. NOTE: An imaginary line extended between these points and beyond both ends should not come within 3 feet of the pool. "A" should always be on the left if the line is between you and the pool.
  2. Mark points around the edge of the pool at the BEAD RECEIVER, NOT the edge of the coping, approximately 2-3 feet apart (1 foot or so on a tight radius). Put marks at the shallow end break line on both sides. Also where the transition slope meets the hopper pad. This line does not extend to the wall, so you will have to sight this line yourself. Number EACH of these marks.
  3. Measure from point A to point 1 and from B to 1. Record the measurements on a chart like the one shown. Repeat for all points and mark which numbers are at the break lines (4 points X1, X2, X3, X4).
  4. Indicate whether the transition slope lines are straight or curved (see drawing)
  5. Measure the back and side slopes, and the hopper pad length and width.
  6. Measure the shallow end from the center of the break line to the center of the shallow end wall.
  7. Measure from the left corner of the shallow end to the left corner of the hopper pad, and the same for the right side (V to X2 & T to X4).
  8. Measure the shallow end depth and the hopper depth at the corners of the pad.
  9. Measure the perimeter of the entire pool at the bead.
  10. If there is a step, indicate its location by marking points at each corner of the step and assigning numbers to them. On the form, indicate which points correspond to the step corners. For added accuracy you can measure from one or both of the shallow end "corners" to both step corners (X2 to S & X2 to R).
  11. Indicate the direction of the pool and the end you are standing at to determine this (i.e. left from deep end). Also include a rough sketch showing the direction, location of the A & B points, and bottom configuration.

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