diff --git a/modules/networking/vpc_subnets/README.md b/modules/networking/vpc_subnets/README.md
index 516548c..d7923c9 100644
--- a/modules/networking/vpc_subnets/README.md
+++ b/modules/networking/vpc_subnets/README.md
@@ -1,4 +1,5 @@
 # Overview
+
 This module performs the following tasks:
 
 - Create VPC, vpcflow log
@@ -6,41 +7,46 @@ This module performs the following tasks:
 - Create IGW, NGW
 
 ## Subnet addressing
-This module takes in the VPC cidr. Then add 4 bits to the netmask and divide the cidr into 2 ranges.
-First range will be used for private subnet and second for public subnets. 
-Another 4 bits are added to these ranges for each subnet.
 
-For example, if the VPC cidr is 10.2.0.0/16, the following subnets will be created:
+Subnet cidrs are calculated automatically. Due to the design of terraform's cidrsubnets, this module has limitations: 
 
-| Subnet Type | Subnet AZ1 | Subnet AZ2 | Subnet AZ3 |
-|-------------|------------|------------|------------|
-| Private  | 10.2.0.0/24 | 10.2.1.0/24 | 10.2.2.0/24 |
-| Public   | 10.2.16.0/24 | 10.2.17.0/24 | 10.2.18.0/24 |
+* supports 2, 4, 6, or 8 subnets in total. 
+* hard-coded to work with 2 AZs, regardless of number of AZs available in the region. 
 
-The VPC cidr netmask should be /20 or above, to produce subnets with /28 netmasks or above.
-Subnet smaller than /28 is unlikely useful. 
+Based on the input variables, it will create subnet cidrs using the following function
+
+| Private Subnets per az | Public Subnets per az | Function                                     | Example if a /24 is used on VPC |
+| ---------------------- | --------------------- | -------------------------------------------- | ------------------------------- |
+| 1                      | 0                     | cidrsubnets(local.vpc-cidr, 1,1)             | 2 * /25                         |
+| 1                      | 1                     | cidrsubnets(local.vpc-cidr, 2,2,2,2)         | 4 * /26                         |
+| 2                      | 1                     | cidrsubnets(local.vpc-cidr, 3,3,3,3,3,3)     | 6 * /27                         |
+| 2                      | 2                     | cidrsubnets(local.vpc-cidr, 4,4,4,4,4,4,4,4) | 8 * /28                         |
+
+simple-divide = local.total-no-subnets >=8 ? cidrsubnets(local.vpc-cidr, 4,4,4,4,4,4,4,4) : local.total-no-subnets >=6 ? cidrsubnets(local.vpc-cidr, 3,3,3,3,3,3) : local.total-no-subnets >=4 ? cidrsubnets(local.vpc-cidr, 2,2,2,2) : local.total-no-subnets >=2 ? cidrsubnets(local.vpc-cidr, 1,1) : null
 
 ## Inputs:
-| Name | Description | Type | Default | Required |
-|------|-------------|------|---------|:-----:|
-| application | name of application | string | none | yes |
-| environment | capacity of environment (prd/dev/lab) | string | none | yes | 
-| customer-name | owner of aws resources | string | none | yes |
-| project | name of project | string | none | yes |
-| default-tags | tags to be added to resources | list | none | yes | 
-| number-of-private-subnets-per-az | number of private subnets per az | number | 0 | yes |
-| number-of-public-subnets-per-az | number of public subnets per az  | number | 0 | yes |
-| create-nat-gateway | whether to deploy NAT gateway for private subnets | bool | true | yes |
-| vpc-cidr | VPC cidr | string | none | yes |
-| enable-flowlog | whether to enable vpc flowlog | bool | true | yes |
-| vpcflowlog-retain-days | number of days to retain vpc cloudwatch log | number | 90 | yes |
-| aws-region-short | short name of aws region (e.g. apne1) | string | none | yes |
-| aws-region | aws region (e.g. ap-northeast-1) | string | none | yes |
-| vpcflowlog-cwl-loggroup-key-arn | kms key alias arn for log group encryption | string | none | yes |  
+
+| Name                             | Description                                       | Type   | Default | Required |
+| -------------------------------- | ------------------------------------------------- | ------ | ------- |:--------:|
+| application                      | name of application                               | string | none    | yes      |
+| environment                      | capacity of environment (prd/dev/lab)             | string | none    | yes      |
+| customer-name                    | owner of aws resources                            | string | none    | yes      |
+| project                          | name of project                                   | string | none    | yes      |
+| default-tags                     | tags to be added to resources                     | list   | none    | yes      |
+| number-of-private-subnets-per-az | number of private subnets per az                  | number | 0       | yes      |
+| number-of-public-subnets-per-az  | number of public subnets per az                   | number | 0       | yes      |
+| create-nat-gateway               | whether to deploy NAT gateway for private subnets | bool   | true    | yes      |
+| vpc-cidr                         | VPC cidr                                          | string | none    | yes      |
+| enable-flowlog                   | whether to enable vpc flowlog                     | bool   | true    | yes      |
+| vpcflowlog-retain-days           | number of days to retain vpc cloudwatch log       | number | 90      | yes      |
+| aws-region-short                 | short name of aws region (e.g. apne1)             | string | none    | yes      |
+| aws-region                       | aws region (e.g. ap-northeast-1)                  | string | none    | yes      |
+| vpcflowlog-cwl-loggroup-key-arn  | kms key alias arn for log group encryption        | string | none    | yes      |
 
 ## Outputs:
-| Name | Description | Type |
-|------|-------------|------|
-| vpc_id | vpc id | string |
-| public_subnets | list of cidr blocks | list |
-| private_subnets | list of cidr blocks | list |
+
+| Name            | Description         | Type   |
+| --------------- | ------------------- | ------ |
+| vpc_id          | vpc id              | string |
+| public_subnets  | list of cidr blocks | list   |
+| private_subnets | list of cidr blocks | list   |
diff --git a/modules/networking/vpc_subnets/variables.tf b/modules/networking/vpc_subnets/variables.tf
index ecf85a9..6ef6931 100644
--- a/modules/networking/vpc_subnets/variables.tf
+++ b/modules/networking/vpc_subnets/variables.tf
@@ -11,7 +11,7 @@ locals {
 
 # VPC variables
 variable "vpc-cidr" {}
-/*
+
 variable number-of-public-subnets-per-az {
   type = number
   default = 0
@@ -20,7 +20,7 @@ variable number-of-private-subnets-per-az {
   type = number
   default = 0
 }
-*/
+
 variable "create-nat-gateway" {
   type    = bool
   default = false
@@ -34,8 +34,8 @@ variable "vpcflowlog-retain-days" {
   default = 90
 }
 variable "vpcflowlog-cwl-loggroup-key-arn" {}
-variable "private-subnet-cidrs" {}
-variable "public-subnet-cidrs" {}
+# variable "private-subnet-cidrs" {}
+# variable "public-subnet-cidrs" {}
 variable "create-free-vpc-endpoints" {
   type    = bool
   default = true
diff --git a/modules/networking/vpc_subnets/vpc.tf b/modules/networking/vpc_subnets/vpc.tf
index fa18d33..94f891c 100644
--- a/modules/networking/vpc_subnets/vpc.tf
+++ b/modules/networking/vpc_subnets/vpc.tf
@@ -3,16 +3,26 @@ data "aws_availability_zones" "available-az" {
 }
 
 locals {
-  subnet_start = cidrsubnets(var.vpc-cidr, 1, 1) # divide vpc into 2
+  // subnet_start = cidrsubnets(var.vpc-cidr, 1, 1) # divide vpc into 2
+  # no-az = length(data.aws_availability_zones.available-az.id)
+  no-az = 2 # hard-coding to 2AZ
+  vpc-cidr = var.vpc-cidr
+  total-no-subnets = local.no-az * (var.number-of-private-subnets-per-az + var.number-of-public-subnets-per-az)
+
+  simple-divide = local.total-no-subnets >=8 ? cidrsubnets(local.vpc-cidr, 4,4,4,4,4,4,4,4) : local.total-no-subnets >=6 ? cidrsubnets(local.vpc-cidr, 3,3,3,3,3,3) : local.total-no-subnets >=4 ? cidrsubnets(local.vpc-cidr, 2,2,2,2) : local.total-no-subnets >=2 ? cidrsubnets(local.vpc-cidr, 1,1) : null
+  public-subnets = slice(local.simple-divide, 0, var.number-of-public-subnets-per-az * local.no-az)
+  private-subnets = slice(local.simple-divide, var.number-of-public-subnets-per-az * local.no-az , local.total-no-subnets)
 }
 
 resource aws_subnet private-subnets {
-  count = length(var.private-subnet-cidrs)
+  count = length(local.private-subnets)
+  # count = length(var.private-subnet-cidrs)
   # count = var.number-of-private-subnets-per-az * length(data.aws_availability_zones.available-az.names)
   vpc_id = aws_vpc.vpc.id
   availability_zone = element(data.aws_availability_zones.available-az.names, count.index)
   # cidr_block = cidrsubnet(local.subnet_start[0], 2, count.index)
-  cidr_block = var.private-subnet-cidrs[count.index]
+  # cidr_block = var.private-subnet-cidrs[count.index]
+  cidr_block = local.private-subnets[count.index]
   tags = merge(
   var.default-tags,
   {
@@ -22,12 +32,14 @@ resource aws_subnet private-subnets {
 }
 
 resource aws_subnet public-subnets {
-  count = length(var.public-subnet-cidrs)
+  count = length(local.public-subnets)
+  # count = length(var.public-subnet-cidrs)
   # count = var.number-of-public-subnets-per-az * length(data.aws_availability_zones.available-az.names)
   vpc_id = aws_vpc.vpc.id
   availability_zone = element(data.aws_availability_zones.available-az.names, count.index)
   # cidr_block = cidrsubnet(local.subnet_start[1], 2, count.index)
-  cidr_block = var.public-subnet-cidrs[count.index]
+  # cidr_block = var.public-subnet-cidrs[count.index]
+  cidr_block = local.public-subnets[count.index]
   tags = merge(
   var.default-tags,
   {
@@ -54,7 +66,7 @@ resource "aws_vpc" "vpc" {
 }
 
 resource "aws_internet_gateway" "igw" {
-  count = length(var.public-subnet-cidrs) > 0 ? 1 : 0
+  count = var.number-of-public-subnets-per-az > 0 ? 1 : 0
   vpc_id = aws_vpc.vpc.id
 
   tags = merge(
@@ -88,7 +100,7 @@ resource "aws_nat_gateway" "ngw" {
 }
 
 resource aws_route_table public-route-table {
-  count = length(var.public-subnet-cidrs) > 0 ? 1 : 0
+  count = var.number-of-public-subnets-per-az > 0 ? 1 : 0
   vpc_id = aws_vpc.vpc.id
   tags = merge(
   var.default-tags,
@@ -99,7 +111,7 @@ resource aws_route_table public-route-table {
 }
 
 resource aws_route_table private-route-table {
-  count = length(var.private-subnet-cidrs) > 0 ? 1 : 0
+  count = var.number-of-private-subnets-per-az > 0 ? 1 : 0
   vpc_id = aws_vpc.vpc.id
   tags = merge(
   var.default-tags,
@@ -110,7 +122,7 @@ resource aws_route_table private-route-table {
 }
 
 resource "aws_route" "public-routes" {
-  count = length(var.public-subnet-cidrs) > 0 ? 1 : 0
+  count = var.number-of-public-subnets-per-az > 0 ? 1 : 0
 
   destination_cidr_block = "0.0.0.0/0"
   gateway_id             = aws_internet_gateway.igw[0].id
@@ -118,7 +130,7 @@ resource "aws_route" "public-routes" {
 }
 
 resource "aws_route" "private-routes" {
-  count = length(var.private-subnet-cidrs) > 0 && var.create-nat-gateway ? 1 : 0
+  count = var.number-of-private-subnets-per-az > 0 && var.create-nat-gateway ? 1 : 0
 
   destination_cidr_block = "0.0.0.0/0"
   nat_gateway_id         = aws_nat_gateway.ngw[0].id