Pipe Slope Calculator

Site drainage · gravity pipework

Drainage Slope Calculator

Work out fall, invert levels and pipe length in metres for gravity drainage runs, and check your gradient against Dubai Building Code / IPC and Dubai Municipality minimum-slope requirements.

Calculate

m
m
1 :
Fall over run
0.100 m
Invert out: —
Fall
100 mm
Gradient
1.000 %
Gradient
10.00 mm/m
IL IN IL OUT L = 10.00 m fall Profile sketch — slope exaggerated for legibility, not to scale

Check against minimum code slope

– Enter a run above to check its slope against the minimum for this pipe size.

IPC Table 704.1 sets minimum slope by pipe size for internal soil & waste pipework. Ratios shown are the metric equivalent of the code’s inch-per-foot values.

Reference tables — minimum slope by pipe size

IPC Table 704.1 — internal drainage

Pipe sizeMin. slopeRatiomm/m

DM Guidelines Table 3–5 — sewer mains

Ø mmMin. mm/mRatio

Dubai Municipality figures are the minimum self-cleansing gradients from the DM Sewerage Design Guidelines (Table 3–5), based on a minimum design velocity of 0.75 m/s and maximum 2.5 m/s; actual sewer design still needs a full hydraulic check (Colebrook–White / Manning) for the real flow and pipe roughness. IPC figures are Table 704.1 of the International Plumbing Code, converted from inch-per-foot to metric. Codes are revised periodically — confirm current figures against the live documents before using them on a submission.

Sources: Dubai Municipality Sewerage Design Guidelines · 2021 International Plumbing Code, Ch. 7