Planning-ready PDF reports £79 +VAT (£94.80 inc VAT) — nitrogen, phosphorus, or both nutrients in one report.
Runs entirely in your browser. See your budget update as you work.
Stuck behind a nutrient neutrality condition?
If your site sits in one of Natural England's protected catchments, the planning authority can't grant permission until you've shown your scheme is "nutrient neutral" — that it won't add nitrogen or phosphorus to waters that are already overloaded. That's the wall a lot of small developments hit. NutrientMonkey gets you over it: build the assessment on screen, watch your budget in kg/year update as you go, and export the report when it's right.
What it costs elsewhere
Consultant nutrient assessments routinely run into the hundreds of pounds per scheme. NutrientMonkey is free to use — model the dwellings, the waste-water route and any SuDS, and see the budget live. You pay £79 +VAT only when you export the planning-ready PDF. If you'd sooner we just did the whole thing for you, get in touch and we will.
The calculation planning wants
NutrientMonkey implements Natural England's nutrient-budget methodology (NECR459 and the catchment calculators) — the five-worksheet flow condensed onto one page: waste water, current land use, future land use, SuDS, then the final budget with the precautionary ×1.2 (20%) buffer. For new dwellings the waste-water term does most of the work, and it's computed exactly. Off-mains, on-mains and post-2030 permit scenarios are all handled.
How it works
- Pick your catchment — all 27 are in the list, each flagged nitrogen, phosphorus or both; the nutrient toggle locks itself to match.
- Enter the dwellings & waste water — occupancy, water use (125 or 110 l/p/d plus NE's allowance), and the drainage route (septic, package plant or mains permit).
- Add land use & SuDS — current vs future land cover and any sustainable drainage, with editable export coefficients so you can paste the official catchment values.
- Export when ready — a branded, planning-ready PDF: the budget in kg/year, every input, and a colour-coded section per nutrient where both apply.
Know your harbour
The nutrient that applies isn't always the obvious one. Chichester Harbour falls inside the Solent (nitrogen); Christchurch Harbour is the River Avon SAC (phosphorus) — a different nutrient from neighbouring Poole Harbour, which is nitrogen. Dual-nutrient catchments such as Stodmarsh and The Broads need both, and NutrientMonkey runs the two budgets together (each with its own credits, exactly as NE's own calculator is run).
Honest about what it is
This is a nutrient-methodology assessment built to support your planning application — fast, clear, and ready to discuss with your case officer. The official Natural England catchment calculator remains the statutory tool, and your figures should reproduce in it; the report states this plainly. We'd rather tell you that up front than dress it up as something it isn't.
What's changing: the Nature Restoration Fund
Nutrient neutrality is in the middle of its biggest shake-up since 2019. The Planning and Infrastructure Act 2025 (Royal Assent December 2025) introduces Environmental Delivery Plans funded through a Nature Restoration Fund: instead of sourcing their own mitigation scheme by scheme, developers will be able to pay a Nature Restoration Levy to Natural England, which delivers the mitigation strategically across a whole area. The secondary legislation is now being laid: the Environmental Delivery Plans (Appropriate Prioritisation) Regulations 2026 came into force on 9 July 2026, the draft Nature Restoration Levy Regulations 2026 have been published, and Natural England is about to launch its formal consultation on the first draft nutrient EDP. Natural England is preparing 16 nutrient EDPs in all. Until an EDP is in force for your catchment the existing regime still applies — you calculate the budget and secure mitigation exactly as now — so NutrientMonkey's methodology is unchanged. We track these changes and will update the tool as EDPs go live.
Who it's for
Developers and self-builders who've hit a nutrient neutrality condition and want to understand their budget before committing to credits; architects and planning consultants pricing up a scheme; and anyone who needs a clear, defensible nutrient figure to put in front of a planning authority. Want it handled end to end? That's what we're here for.
Find your catchment
Every Natural England catchment has its own page with the nutrient that applies and a calculator set up for it. Jump straight to yours:
- Poole Harbour N
- Solent N
- Tees (Teesmouth) N
- Lindisfarne N
- Stodmarsh N & P
- The Broads N & P
- River Wensum N & P
- Chesil & the Fleet N & P
- Hornsea Mere N & P
- Oak Mere N & P
- Rostherne Mere N & P
- West Midlands Mosses N & P
- River Clun N & P
- River Avon (Christchurch) P
- Somerset Levels & Moors P
- River Itchen P
- River Axe P
- River Camel P
- Derwent & Bassenthwaite P
- River Eden P
- River Kent P
- River Lambourn P
- River Lugg P
- River Mease P
- Esthwaite Water P
- Peak District Dales P
- Roman Walls Loughs P
Frequently asked questions
What is nutrient neutrality, and why has my planning been held up?
In certain catchments, new homes can't add nitrogen or phosphorus to already-overloaded protected waters. Natural England requires new dwellings there to be 'nutrient neutral' — so the planning authority can't grant permission until you've shown your scheme's nutrient budget and how any excess is offset. NutrientMonkey works out that budget for you.
Which catchments and nutrients does it cover?
All 27 Natural England catchments, each correctly flagged for nitrogen, phosphorus, or both. Nitrogen examples include Poole Harbour and the Solent (which covers Chichester Harbour); the River Avon SAC around Christchurch is phosphorus — a common trap, since it sits right next to nitrogen-led Poole. Dual-nutrient catchments like Stodmarsh and The Broads are assessed for both at once.
Is NutrientMonkey free to use?
Yes — building your assessment on screen and seeing your nutrient budget in kg/year is completely free. You only pay to export the planning-ready PDF report: £79 +VAT (£94.80 inc VAT).
Does it work offline — can I install it as an app?
Yes. NutrientMonkey installs on your phone or desktop like an app and works fully offline — your assessment autosaves in this browser, and you only need a connection when you export the paid PDF.
Is this the official Natural England calculator?
No, and we're upfront about that. NutrientMonkey implements NE's published nutrient-budget methodology (NECR459 and the catchment calculators) to give you a fast, planning-support assessment. The official NE catchment calculator remains the statutory tool, and the report says so — your final figures should reproduce in it. The land-use export coefficients are left as editable fields with indicative defaults, because the real values are specific to your catchment, soil and rainfall and should be taken from the official lookup.
How is the nutrient budget actually calculated?
It follows NE's five-worksheet flow, condensed onto one page: waste water, current land use, future land use, SuDS, then the final budget with the ×1.2 (20%) precautionary buffer. For new dwellings the waste-water term dominates: occupancy × dwellings × water use (l/p/d) × 365 × concentration ÷ 1,000,000. Defaults are 2.4 occupants and 125 l/p/d (or 110) plus NE's 10 l/p/d allowance, with septic-tank, package-treatment-plant and mains-permit options built in.
How many credits will I need?
Where a treatment-works permit tightens at April 2030, NutrientMonkey gives you a pre-2030 and a post-2030 budget. If you buy permanent credits only, you need the greater of the two (floored at zero) — a permanent purchase sized to the higher pre-2030 load also covers the lower post-2030 load. Or you can split it: cheaper temporary credits (valid to 1 April 2030) for the pre-2030 excess, plus permanent credits for the enduring post-2030 baseline. The tool shows all three figures — pre, post and the permanent total — live, and one credit is 1 kg of nutrient per year. Credit prices vary hugely by scheme and aren't baked in; an on-screen panel lists indicative, dated prices where they're verifiable (Poole and Tees have official NE prices, and the Cumbria partnership scheme now publishes official prices for the Eden, Derwent & Bassenthwaite, Kent and Esthwaite catchments). Heads-up: schemes disagree on what 'a credit' means — NE uses 1 kg, some private schemes use 0.1 kg — so the tool works in £/kg.
Is nutrient neutrality changing with the Nature Restoration Fund?
Yes, but not yet in a way that changes your assessment today. The Planning and Infrastructure Act 2025 (Royal Assent December 2025) introduces Environmental Delivery Plans (EDPs) funded through a Nature Restoration Fund, where developers pay a Nature Restoration Levy to Natural England instead of sourcing their own mitigation. Natural England is preparing 16 nutrient EDPs; the NRF secondary legislation is now being laid (the Appropriate Prioritisation Regulations came into force on 9 July 2026 and the draft Nature Restoration Levy Regulations are published), and the consultation on the first draft nutrient EDP is imminent. Until those EDPs are in force for your catchment, the existing nutrient-neutrality regime still applies — you calculate the budget and secure mitigation as now — so NutrientMonkey's methodology is unchanged. We'll update the tool as EDPs go live.
Can I re-export after fixing a typo?
Yes — project details can be corrected and re-exported free for 24 hours after payment. Changing the actual budget figures needs a new export.