At Togal, you can create custom mathematical calculations for your quantity output within each classification, and use it to achieve different goals. Refer to this page for a tutorial on creating custom formulas.
The following are examples demonstrating how custom formulas can be applied to various quantity takeoff purposes.
Add Waste Factor to Quantities
You might need to add a waste allowance on top of the measured takeoff quantity. The Custom Formula allows you to automatically calculate the “with waste” quantity so you don’t have to calculate it manually.
For example, you are estimating flooring with 5% waste. After you obtain the total floor area (SF) from an Area classification, add a Custom Formula output that multiplies the base area by 1.10 to obtain the “with waste” quantity.
Unit Conversions
Many estimates use pricing units that don’t match the raw takeoff units. With Custom Formula, you can convert units directly.
For example, Vapor barrier is typically priced per 100 SF (SQ). After obtaining the total gross floor area from an area classification, you can use the Custom Formula to divide the area in SF by 100, to directly get the actual quantity for Vapor barrier in SQ.
Reinforcement Calculation
Reinforcement is typically priced by weight in tons. The estimation process involves four steps:
Determine the total linear footage (LF) of the reinforcement;
Check the Rebar Weight Factor Conversion Table** and get the Weight per Unit Length factor (in lb/ft) for the specific rebar size;
**Rebar Weight Factor Conversion Table
Calculate total rebar weight in pounds (lb) by multiplying the results from Step 1 and Step 2;
Convert the result from Step 3 from pounds to ton (1 ton = 2,000 lb).
Rebar Calculation Example
Step 1: Determine the total LF of the reinforcement
Longitudinal Reinforcement
The left image shows a cross section view of a 12” x 8” column. The total height of the column is 10ft, with 4 #5 longitudinal reinforcement and #5 @8" transverse reinforcement. Determine the reinforcement quantities needed for the column. |
Length of each long bar = 10'
Total length of long bar (lf) = 10' x 4 bars = 40'
Transverse Reinforcement
Length of each tie = (12" + 8") x 2 / (12" / 1') = 3.33'
Number of ties = ⌈Height of Column / Tie Spacing⌉ + 1
= ⌈10' / (8" / (12" / 1'))⌉+ 1
= 16
Total length of ties (lf) = 3.33' x 16 ties = 53.28'
Step 2: Check the conversion table to get the Weight per Unit Length factor (in lb/ft)
For #5 bars, the weight factor is 1.043 lb/ft.
Step 3: Calculate total rebar weight (in lb)
Longitudinal Rebar Weight (lb) = 40' x 1.043 lb/ft = 41.72 lb
Transverse Rebar Weight (lb) = 53.28' x 1.043 lb/ft = 55.57 lb
Step 4: Calculate total rebar weight (in ton)
Longitudinal Rebar Weight (ton) = 41.72 lb / 2000 lb/ton = 0.02 ton
Transverse Rebar Weight (ton) = 55.57 lb / 2000 lb/ton = 0.03 ton
Following these calculation steps, the custom formula can directly take the numerical values from the classification and calculate the rebar weight.